Tamiasciurus and Sciurus likely diverged in the late Pliocene. Red squirrels are first reported in the Irvingtonian and are now known from more than 30 late Rancholabrean faunas from the central and eastern United States.
Red squirrels have well-developed and extremely acute senses of smell, sight, and hearing. They are well known for their ability to communicate by calls. These calls consist of rattles, screeches, growls, buzzes and chirps and are often used in defense of territory or in response to threats from predators. During mating, red squirrels use low aggressive calls or territorial calls to drive off subordinate males. Red squirrels may even be able to recognize each other by individual call. Communication is important because of their territorality. They intensively use vocal communication to advertise these territories and to threaten other squirrels. Both vocal and scent marking aid in the recognition of individuals. Olfactory communication is important because it can leave long-lasting impressions which advertise if the territory is taken and males can discriminate between different olfactory signatures of other males. Another reason chemical communication is advantageous is because it may also reduce predation risk. Scent marking may also enable the squirrels to avoid unnecessary chases and fights by becoming known to their neighbors. Red squirrels may also be able to make predator-specific calls, but evidence of this is still very inconclusive. Red squirrels tend to produce a high-frequency call for aerial predators and a harsher, bark-type call for terrestrial predators. However, it is more commonly observed that these two call types are mixed.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
As of 2008, red squirrels are classified as Least Concern on the ICUN Red List and by the United States government. They are widespread and common, have suitable habitat throughout their range, and face no major threats. One subspecies, Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis), is endangered according to the ICUN Red List. This subspecies is only found in southeast Arizona and its population is about 150 individuals.
US Federal List: endangered
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Red squirrels cause considerable economic losses. They interfere with conifer reforestation by eating 60 to 100% of cone crops and directly damaging trees through bud consumption and bark stripping. Squirrels also cause damage to human property by nesting in homes and gnawing on household items. They may bite humans if provoked.
Negative Impacts: injures humans (bites or stings); household pest
Red squirrels are the third-most commonly harvested furbearer in Canada, bringing in about $1 million annually. Each year in Minnesota, thousands of red squirrels are harvested for consumption by humans. Red squirrels are an important prey item for other economically important species like lynx (Lynx) and martens (Martes).
Positive Impacts: food ; body parts are source of valuable material
Red squirrels impact the forest ecosystem by dispersing seeds and fungi through caching and forgetting about or otherwise failing to return to food caches. The diversity and abundance of beneficial ectomycorrhizal fungi in these caches helps young trees acquire nutrients and grow. They limit the regrowth of trees by eating the seeds and inner tissues of the trees, which can cause significant damage to tree survival and value. Red squirrels provide a feeding opportunity for porcupines (Erethizontidae) during the winter by peeling away the bark of lodgepole pines. Their feeding habits also cause conifers to grow multiple tops, which reduces their timber value but increases suitable nest sites for many arboreal rodents (Rodentia) and passerine birds (Passeriformes). The increased availability of nest sites sustains species richness.
Red squirrels are host to a variety of endoparasites and ectoparasites. Endoparasitic species include 9 species of nematodes, 9 species of tapeworms including the genus (Hymenolepis). Other endoparasites include tularemia bacteria (Francisella tularensis) and Emmonsia crescens), and some kinds of protists like sarocysts (Sarocystis), and (Haplosporanigium). They are also vulnerable to fungal lung disease infection via adiaspiromycosis (Emmonsia parva). Ectoparasites of red squirrels include 31 species of mites, ticks, and chiggers (Glycyphagidae and Acarina), 25 species of fleas including Siphonaptera, Opisodasys robustus, Orchopeas caedens, Orchopeas neotomae, Orchopeas leucopus, Oropsylla idahoensis, Ceratophyllus vison. They may also carry botfly larvae (Cuterebra emasculator). Viruses that infect red squirrels are silverwater virus, California encephalitis virus, and Powassan virus.
Ecosystem Impact: disperses seeds
Commensal/Parasitic Species:
Red squirrels are primarily granivorous, but they are also opportunistic omnivores in the absence of mast foods. Primary diet items vary with habitat and include the seeds of conifers and other tree types detailed below. They live in a resource pulse system, where foods (conifers like white spruce, Picea glauca) exhibit extreme annual variation. They consume a wide variety of mushrooms, including at least 45 species in the Cascade Mountains alone. Secondary food items include tree buds and flowers, fleshy fruits, tree sap, bark, insects, and other animal materials such as bird eggs or young snowshoe hares (Lepus americanus). During winter, spring, and early summer, bark stripping and tree girdling occurs commonly to access phloem and cambial tissues. Red squirrels are highly selective in their foraging behavior, harvesting cones from the tree species with the highest seed energy per cone first and systematically working their way through species of conifers by energy density per cone.
Red squirrels are primarily larder hoarders. In late summer through autumn, they harvest cones and store them in one or a few central middens. Middens are a central hoard that is easy to defend from competitors and provides a moist, cool environment that prevents cones from opening. Middens vary in size and number depending on habitat, food availability, and individual squirrel. However, they contain enough food to last one to two seasons and are often used by several generations of squirrels In the eastern United States and Canada, red squirrels frequently engage in scatter hoarding, which is a system involving many small hoards instead of a large midden. This accounts for 85% of all hoards and more than 50% of all cones stored in this area The downside to this type of storage is that middens only provides enough food for about 37 days. Red squirrels have a great sense of smell which they use when looking for middens during the winter. Some individuals store their food caches underground and are able to locate these seeds, even under 4 meters of snow. Whenever they do not recover a stockpile of food, the seeds are left to germinate.
Red squirrels pilfer food from other squirrels, but the extent varies greatly by population. Some squirrels the Yukon Territory of Canada almost never pilfer. Mt. Graham Red Squirrels, on the other hand, pilfer 97% of the time and in Vermont pilfering occurred 25% of the time. Age, boldness, and population density may play a role in pilfering.
Animal Foods: birds; mammals; eggs; insects
Plant Foods: wood, bark, or stems; seeds, grains, and nuts; fruit; flowers; sap or other plant fluids
Other Foods: fungus
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Granivore )
Biogeographic Regions: nearctic (Native )
Red squirrels occupy northern boreal coniferous forests abundant with conifer seeds, fungi, and interlocking canopies. This limits them to mountain ranges on the southern and eastern boundaries of their range. In the Rocky Mountains they have been found at elevations up to 2,500 ft (762 m). Populations of red squirrels occur in different habit conditions due to the vastness of their range. They occur in both temperate and polar environments and are considered to be primarily arboreal. They can be found in a mixed variety of forests including coniferous, deciduous, and mixed forests and they are also able to thrive in suburban and urban settings, as long as cool, coniferous forests with dense, interlocking canopies and abundant fungal resources are present.
Range elevation: 0 to 762 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: taiga ; forest ; mountains
Other Habitat Features: urban ; suburban ; riparian
Red squirrels exhibit a type 3 survivorship curve in wild populations. This means that most of the mortality is associated with deaths of the young and only 25% survive longer than 1 year. Despite their small size, red squirrels are considered relatively long lived, with the oldest known squirrel in the wild reaching 10 years of age. The longest recorded lifespan in captivity is 9 years. Mature squirrels are 2 to 4 years old and older squirrels are considered to be over 5 to 6 years old. Their average lifespan in the wild is 5 years.
Range lifespan
Status: wild: 10 (high) years.
Range lifespan
Status: captivity: 9 (high) years.
Average lifespan
Status: wild: 5 years.
Average lifespan
Status: captivity: 9.8 years.
Red squirrels differ from other tree squirrels by their deep reddish color, territorial behavior, and their smaller body size. They are less than 30% the size of grey squirrels (Sciurus carolinensis). While size and pelage color can vary geographically, they generally have a reddish back and white underside that is demarcated by dark lateral lines, which are especially visible in summer. A white eye ring is present year-round and tufted ears are during the winter. Variation in the dorsal surface color can range from reddish to ferruginous brown to olivaceous gray, usually with a distinctive reddish or brownish lateral band running down the back. The tail is smaller and flatter than that of other tree squirrels and varies in color from yellowish-gray to rusty red, with a band of black often extending the entire length of tail. Where its range borders that of Douglas squirrels (Tamiasciurus douglasii), red squirrels are distinguished by color of their pelage. The underside of red squirrels is all white or cream, whereas Douglas squirrels are rust colored or with a blackish wash. Tail hairs have yellowish to rusty tips with a black band in red squirrels, whereas those of Douglas squirrels are white-tipped with a black band, making them moderately easy to distinguish from a distance. Male and female red squirrels are very similar in appearance.
Some ecogeographic variation is believed to occur, so length and weight measurements may only hold true for the population(s) in which they were measured. Twenty-five subspecies of red squirrels are recognized. They differ mainly by range distribution. Mass tends to range from 197.3 to 282.2 g, with an average of 212.97. Their total length ranges from 270 to 385 mm, with an average of 327.5. Much of their length is their tail, which is 92 to 158 mm long. Red squirrels have an average hind foot length of 35 to 57 mm and the ear length is 19 to 31 m. Condylobasal length is 42 to 50 mm. Red squirrels have a basal metabolic rate of 166 cm^3 oxygen/hour.
Red squirrels generally experience two annual molts, although the tail molts only once per year. The spring molt occurs from late March through August and starts on the nose and front feet, and ends on the rump. The fall molt is from late August to early December and begins on the tail and then progresses to the rump and the head before ending on the legs and flank. Molt stage can be an important age indicator. Skulls can be aged by looking at dental characteristics such as visible wear and presence of permanent teeth. Their dental formula is I 1/1, C 0/0, P 1/1 or 2/1, M 3/3. The total number of teeth is 20 or 22 depending on the presence of upper P3.
Range mass: 197.3 to 282.2 g.
Average mass: 212.97 g.
Range length: 270 to 385 mm.
Average basal metabolic rate: 166 cm3.O2/g/hr.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Average basal metabolic rate: 1.615 W.
Red squirrels are likely prey for a variety of animals including snakes, birds of prey, and carnivorous mammals. They are preyed upon by Cooper's hawks (Accipiter cooperii), northern goshawks (Accipiter gentilis), bald eagles (Haliaeetus leucocephalus), great gray owls (Strix nebulosa), great horned owls (Bubo virginianus), American kestrels (Falco sparverius), red-shouldered hawks (Buteo lineatus), northern harriers (Circus cyaneus), red-tailed hawks (Buteo jamaicensis), and sharp-shinned hawks (Accipiter striatus). Mammals that prey upon them them are American martens (Martes americana) and fishers (Martes pennanti), weasels (Mustela), mink (Neovison vison), as well as various canids like red foxes (Vulpes vulpes) and felids like lynx (Lynx canadensis). They are also preyed upon by timber rattlesnakes (Crotalus horridus). Humans hunt red squirrels for both their fur and meat.
Alarm calls are the most highly used anti-predator adaptations of red squirrels. Red squirrels tend to produce a high-frequency call for avian predators and a harsher bark-type call for terrestrial predators. However, it is more common that these two call types are mixed when any predator approaches. Red squirrels have a high survival rate even when subjected to heavy predation. It is very hard to catch and kill these animals because they are quite agile and take to the trees or thick vegetation to escape predators. Red squirrels are also fairly aggressive and when cornered, will not hesitate to defend themselves.
Known Predators:
Red squirrels have a defined breeding season lasting 105 days that can occur either once or twice a year. They will mate in early spring from March to May and then again in August to early September. A second breeding period tends to occur in warmer areas of their range. Although mate pairings may occur, red squirrels are generally characterized as promiscuous. Animals in the best condition tend to breed more regularly and successfully than animals in poor condition.
Red squirrels exhibit a scramble competition mating system, in which the main costs to males are locating receptive females. Males typically invade the territory of females in estrus and pursue them in obvious mate chases. During mate chasing, a single dominant male actively pursues a female and drives off other subordinate males using calls or direct chase. Mounting and copulation usually lasts several minutes and occurs several times in the afternoon of the only day the female is receptive. Copulation is frequently initiated by the female and terminated by the male. Mating most often occurs on the ground or in the lower branches of trees. During mating, the male holds the female around the posterior abdomen while resting his head on her back. It is common for both males and females to engage in grooming of the genitals before and after copulation. The adults have no further contact after mating and the male returns to his territory.
Mating System: polygynandrous (promiscuous)
Red squirrels breed once or twice a year, depending on their geographic location. Populations in the south and east generally have two litters a year, one in spring and one in late summer. This pattern occurs all the way up to Quebec and has also occurred in British Colombia. In the northern extent of their range, breeding only occurs once a year, generally in spring. In the eastern United States, two breeding seasons per year is common, one in March and a second in late July. Harsher conditions at the northern latitudes and higher elevations of the squirrels' range most likely limit reproduction to a single breeding season. Interannual variation in female reproduction is also common; there was a halving in the number of breeding females over 2 years in British Columbia. Their reproductive cycle has adapted to the cyclical production of conifer cone output. Female estrus is highest in February to March and June to July. Pregnancy peaks in March to April and August to September in New York. In Colorado, conception generally occurs April to June.
Females are in estrus only 1 day per breeding season. Conception usually occurs within a few hours of mating. Gestation averages 35 days. Newborn young weigh 7.08 g on average. Litter sizes range from 1 to 8 offspring but averages 3.97. Altricial young are born without any hair except vibrissae and fine chin hairs, but develop quickly. The external auditory meatus is obvious at 18 days, eyes open at 26 to 35 days, and pelage is fully developed in only 40 days. Lactation occurs for the first 70 days. After that time, young are cast out to find their own territory. In some cases when the mother is in poor condition she will give part of her territory to her offspring. This increases the probability of survival for the offspring, increasing the overall fitness the mother. Young are active outside the nest in 7 weeks and fully independent shortly after weaning. Dentition is complete and external skeletal measurements reach adult size by 125 days.
Most red squirrel nests are constructed within 30 m of cone caches. Red squirrels prefer natural cavities, but due to lack of such resources in coniferous forests, they construct leaf nests or occasionally underground nests. The most important factors influencing nest-tree selection are tree diameter and branching structure, and the availability of canopy escape routes. Nests are found at heights of 2 to 20 m, and while nest material varies with habitat, they typically include grasses, mosses, inner cambium, shredded bark leaves, feathers, and fur.
Reproduction is dependent on resource abundance. Red squirrels live in a resource-pulse system, where the main food (in most cases the seeds of conifer species like white spruce) fluctuates annually, in some cases spanning three orders of magnitude between failure and mast years. Food available for reproduction in the spring is determined by the abundance of cones produced the previous year. The reliance on and the defense of individual caches allows females to have the potential to assess the level of stored food that is available for current reproduction. However, female squirrels do not have a smaller litter in years of crop failure, so reproduction is expected to be more costly during these years.
Age also affects reproductive cycles in both male and female red squirrels. Females and males are sexually mature at 1 year of age but are still developing. Despite the detriment to their own health by trying to breed and grow simultaneously, 1-year-old females tend to reproduce because they can achieve higher lifetime reproductive success than females delaying their first reproduction. This is also true for young males. Mature females tend to engage in a conservative reproductive strategy in order to allocate reproductive resources only when their own survival costs are maintained. This is not the case for females over 6 years old, who tend to sacrifice their own survival for reproduction because they are unlikely to be able to breed again the following year. Reproduction senescence occurs from 4 years of age onwards.
Breeding interval: Red squirrels breed once or twice a year, depending on their geographic location.
Breeding season: The time of breeding depends on their geographic location.
Range number of offspring: 1 to 8.
Average number of offspring: 3.97.
Average gestation period: 35 days.
Average weaning age: 70 days.
Average time to independence: 7 weeks.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; sperm-storing
Average birth mass: 7 g.
Average gestation period: 37 days.
Average number of offspring: 4.2.
Average age at sexual or reproductive maturity (female)
Sex: female: 342 days.
Females raise the young without any help from males. Gestation averages 35 days and lactation is 70 days. After this the young are no longer dependent on the mother and the offspring relocate to find territories of their own. Mothers sometimes bequeath territories, giving part or all of their territory to one or more of their offspring. This increases the offspring’s’ probability of overwinter survival.
Parental Investment: altricial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
Gwiñver rous Norzhamerika (Tamiasciurus hudsonicus) a zo ur bronneg krigner hag a vev e Stadoù-Unanet Amerika ha Kanada.
L'esquirol vermell americà (Tamiasciurus hudsonicus) és una espècie de rosegador de la família dels esciúrids. Viu als Estats Units i gran part del Canadà. S'alimenta de llavors, pinyes, núcules, fruita i, de tant en tant, invertebrats i petits vertebrats. Els seus hàbitats naturals són els boscos de coníferes, mixtos o caducifolis, així com els arbustars i les zones amb vegetació secundària. Es creu que no hi ha cap amenaça significativa per a la supervivència d'aquesta espècie.[1]
L'esquirol vermell americà (Tamiasciurus hudsonicus) és una espècie de rosegador de la família dels esciúrids. Viu als Estats Units i gran part del Canadà. S'alimenta de llavors, pinyes, núcules, fruita i, de tant en tant, invertebrats i petits vertebrats. Els seus hàbitats naturals són els boscos de coníferes, mixtos o caducifolis, així com els arbustars i les zones amb vegetació secundària. Es creu que no hi ha cap amenaça significativa per a la supervivència d'aquesta espècie.
Das Gemeine Rothörnchen (Tamiasciurus hudsonicus), auch Rothörnchen genannt, ist mit einer Körperlänge von 17 bis 23 und einer Schwanzlänge bis zu 16 Zentimetern ein eher kleiner Vertreter aus der Familie der Hörnchen.
Die Tiere haben eine rotbraune Fellfarbe am Rücken, der Kopf sowie der Bauch- und Brustbereich sind weiß gefärbt. Die Ohren sind nur mit einem sehr kurzen Fellbüschel versehen. Der Schwanz ist ebenfalls rotbraun und mit dünnen schwarzen und gelben Haaren durchzogen; die Spitze ist schwarz. Um die Augen ist ein auffälliger, weißer Ring vorhanden. Die sehr scharfen Krallen dienen den Tieren als Kletterhilfe. Das Gewicht der Einzeltiere beträgt zwischen 140 und 360 Gramm.
Das Gemeine Rothörnchen kommt in Alaska und Kanada mit Ausnahme des hohen Nordens vor. In den Vereinigten Staaten ist es in den Rocky Mountains, den Appalachen und südlich bis Pennsylvania beheimatet, dort bewohnt es die Nadelwälder.
Die tagaktiven Tiere sind Baumbewohner, sie fressen vor allem Samen, aber auch Nüsse, Eicheln, Zapfen, Knospen, Früchte, Pilze, gelegentlich auch Vogeleier, Nestlinge oder kleinere Mäuse. Für den Winter legt das Gemeine Rothörnchen bis zu einen Meter tiefe Vorratskammern am Boden an. Bei Gefahr geben die Tiere eine sehr schrillen Warnlaut, welcher an ein Zirpen erinnert, von sich. Die maximale Lebensspanne der Tiere beträgt ca. 10 Jahre.
Die erste Paarungszeit der Hörnchen ist im Februar oder März, die zweite im Juni oder Juli. Während der Paarungszeit streiten die Männchen sehr aggressiv um die Weibchen. Die Empfängniszeit des Weibchens beträgt nur einen Tag. Nach der Paarung verlassen die Männchen die Weibchen wieder. Nach einer Tragzeit von fünf Wochen kommen zwei bis sieben nackte und blinde Junge zur Welt, welche das Weibchen bis zu sieben Wochen säugt; die Augen öffnen die Jungen erst im Alter von zwei bis drei Wochen. Mit einem Alter von zwei Monaten verlassen die Jungen das elterliche Revier und suchen ein eigenes. Je nach Nahrungsverfügbarkeit kann das Weibchen im Jahr zwei Würfe bekommen. Die Geschlechtsreife erreichen die Tiere im Alter von einem Jahr.
Da diese Art weit verbreitet ist und keine Bedrohungen bekannt sind, wird sie von der IUCN als ungefährdet (Least Concern) geführt. In Kanada werden die Tiere lokal als Lieferant für Pelze bejagt.
Das Gemeine Rothörnchen (Tamiasciurus hudsonicus), auch Rothörnchen genannt, ist mit einer Körperlänge von 17 bis 23 und einer Schwanzlänge bis zu 16 Zentimetern ein eher kleiner Vertreter aus der Familie der Hörnchen.
It Amerikaanske reade iikhoarntsje (Latynske namme: Tamiasciurus hudsonicus) is in sûchdier út it skift fan 'e kjifdieren (Rodentia), de famylje fan 'e iikhoarntsjes (Sciuridae) en it skaai fan 'e Noardamerikaanske reade iikhoarntsjes (Tamiasciurus), dat foarkomt yn in grut part fan Noard-Amearika. Dit bist wurdt pleatslik ek wol it dinne-iikhoarntsje (pine squirrel), de chickaree of de fairydiddle neamd. It Amerikaanske reade iikhoarntsje moat net betizze wurde mei it (gewoane) iikhoarntsje dat ek yn Fryslân foarkomt, en dat ek wol it (Jeropeeske of Jeraziatyske) reade iikhoarntsje neamd wurdt. De wittenskiplike soartenamme hudsonicus ferwiist nei de Hudsonbaai, dêr't it Amerikaanske reade iikhoarntsje yn 1771 foar it earst de soölooch Johann Christian Polycarp Erxleben ûnder eagen kaam.
It Amerikaanske reade iikhoarntsje komt foar yn in grut diel fan Noard-Amearika. Yn Kanada libbet er yn it grutste part fan it lân, útsein it Arktyske noarden en de eilannen Nijfûnlân, Kaap Bretoneilân, Prins Edwardeilân, de Magdalena-eilannen en Anticosti oan 'e eastkust en de Keninginne Sjarlotte-arsjipel oan 'e westkust. Teffens ûntbrekt er yn súdlik Alberta en yn 'e omkriten fan 'e stêd Vancouver, yn it súdwesten fan Britsk-Kolumbia. Yn 'e Feriene Steaten komt it Amerikaanske reade iikhoarntsje foar yn in grut diel fan 'e Rocky Mountains en de Grutte Dobbe, fan 'e Kanadeeske grins oant yn Arizona, mar hy ûntbrekt oan 'e westkust en op it grutste diel fan 'e Grutte Flakten. Wol komt er wer foar yn 'e krite fan 'e Grutte Marren, Nij-Ingelân, it legere noardeasten en yn 'e Appalachen oant yn Georgia.
Amerikaanske reade iikhoarntsjes komme ek op ferskate plakken yn Jeropa foar as eksoat. Hjirby giet it wierskynlik om ûntsnapte eksimplaren út dieretunen of priveekolleksjes. Wierskynlik hat der him lykwols noch gjin fuortplantingspopulaasje fêstige. Yn Nederlân binne Amerikaanske reade iikhoarntsjes op ferskate plakken synjalearre, wêrûnder eastlik fan Arnhim, op it Waadeilân Teksel en op 'e Peel. Yn Fryslân hawwe der twa waarnimmings west yn Gaasterlân en ien by Dronryp. Yn 2018 wiene der fierders teminsten fjouwer Amerikaanske reade iikhoarntsjes yn 'e Ljouwerter Bosk, hoewol't der nei ferrin fan tiid noch mar ien waarnommen waard. De Rykstsjinst foar Undernimmend Nederlân (RVO), waard yn july fan dat jier foar de rjochter dage troch it Platfoarm Stopje Ynvasive Eksoaten, om 'e oerheid te twingen en fang de bisten út 'e Ljouwerter Bosk wei.[1] Op 21 augustus 2018 die de rjochter útspraak dat it lêste Amerikaanske reade iikhoarntsje, dat fan fans de namme 'Boefke' krigen hie, yn 'e Ljouwerter Bosk bliuwe mocht, om't er mar "beheinde aksjeradius" hie en him allinnich net fuortplantsje koe.[2]
It Amerikaanske reade iikhoarntsje hat trochinoar in kop-romplingte fan 16½-23 sm, mei in sturtlingte fan 9-16 sm en in gewicht fan 140-310 g. Hy is lytser as de oare beambewenjende iikhoarntsjes dy't yn Noard-Amearika foarkomme en hat in opfallende tekening, mei in readbrune rêch en in wite bealch, dy't faninoar skaat wurde troch in skerpe demarkaasjeline. De sturt hat krekt as by oare beambewenjende iikhoarntsjes de foarm fan in plomsturt, en wurdt û.m. brûkt om it lykwicht te hâlden by it klimmen en draven yn 'e beammen en as roer by it springen.
Amerikaanske reade iikhoarntsjes binne fanwegen harren dieet fan konifearesied sterk bûn oan it foarkommen fan nullebeammen. Sadwaande libje se fral yn nullewâlden en wurdt harren ferspriedingsgebiet mear beheind troch de noard- en súdgrins fan 'e taigasône as troch klimatologyske faktoaren. Inkeld oan 'e westkust fan 'e Feriene Steaten ûntbrekke se yn 'e nullewâlden, mei't dy dêr it domein binne fan it nau besibbe douglasiikhoarntsje (Tamiasciurus douglasii). Resint liket it Amerikaanske reade iikhoarntsje syn areaal ek út te wreidzjen nei mingde wâlden dy't foar it meastepart út leafbeammen besteane.
It Amerikaanske reade iikhoarntsje is inkeld oerdeis aktyf en hat in eksklusyf territoarium, dat er it hiele jier rûn fûleindich ferdigenet tsjin soartgenoaten, mei as iennichste útsûndering de peartiid. Hy makket syn nêst fan gers heech yn 'e beammen of soms yn holtes yn 'e stammen fan spjirren, popelieren of nutebeammen. Nêsten op 'e grûn binne tige seldsum. Elts eksimplaar ûnderhâldt ferskate nêsten yn syn territoarium, en wyfkes mei jongen ferhúzje dy geregeldwei fan it iene nei it oare nêst. Der binne in pear gefallen bekend fan Amerikaanske reade iikhoarntsjes dy't har nêst makken yn minsklike wenten en dêrby isolaasjemateriaal brûkten om it nêst te beklaaien.
It wyfke fan it Amerikaanske reade iikhoarntsje is mar ien dei djoeisk, mar foarôfgeande dêroan bejout se har bûten har eigen territoarium, wat nei alle gedachten de mantsjes yn 'e omkriten fan har oansteande djoeiskens op 'e hichte stelt. Op 'e dei dat se djoeisk is, wurdt se neisitten troch ferskate mantsjes, dy't allegear besykje de konkurrinsje fuort te jeien. Dat slagget lykwols nea, en it wyfke pearet feitliks mei 4-16 ferskillende mantsjes, wat in frij opmerklik barren is yn 'e bistewrâld. (In mantsje dat mei mear as ien wyfke pearet komt withoefaak foar, mar in wyfke dat mei mear as ien mantsje pearet is folle seldsumer.) Nei in draachtiid fan 31-35 dagen smyt it wyfke dan in nêst fan 1-5 (mar meastal 3-4) jongen, dy't keal te wrâld komme, mei in gewicht fan sa'n 10 g. Dy ferlitte it nêst foar it earst as se 42 dagen of dêromtrint binne, wurde mei 70 dagen ôfwûn en binne mei 125 dagen folgroeid en selsstannich.
De wyfkes kinne it jiers nei harren berte dielnimme oan 'e fuortplanting, mar guon wachtsje dêrmei oant se twa of trije jier binne. De measte wyfkes bringe mar ien nêst yn 't jier te wrâld, mar soms slane se in jier oer, wylst guon soms ek twa ferskillende nêsten jongen yn ien jier produsearje. Amerikaanske reade iikhoarntsjes hawwe trochinoar mar 22% kâns om it earste jier te oerlibjen. Dêrnei is de libbensferwachting lykwols trochinoar 2⅓ jier mei in maksimum fan 8 jier. Har wichtichste natuerlike fijannen binne de Kanadeeske lynks, reade lynks, prêrjewolf, Amerikaanske oehoe, (gewoane) hauk, readsturtmûzefalk, Amerikaanske krie, Amerikaanske marter, (gewoane) foks, grize foks, wolf en wezeling.
Amerikaanske reade iikhoarntsjes frette benammentlik sieden fan nullebeammen, mar foegje op opportunistyske wize ek wol oare gaadlike saken oan har menu ta. Dêrûnder binne beamknoppen en -nullen, en fierders poddestuollen (wêrûnder guon dy't foar minsken deadlik giftich binne), skimmels en blêden fan 'e wylch, de popelier en de bearedrúf. Ek frette se inkeld wol fûgelaaien en sels wol jongen fan 'e Amerikaanske hazze. Fierwei it grutste part fan har fretten krije se lykwols út sieden dy't se út spjirre-apels helje. Dêrfan lizze se hjerstmis in foarrie oan op ien plak, dêr't se dan winterdeis op tarre. Om by it sied te kommen, moatte se de skobben fan 'e spjirre-apels ôfbrekke, en dy smite se dan op ien bulte, dy't in rúchskerne neamd wurdt, en dy't wol in meter yn trochsneed wurde kin.
It Amerikaanske reade iikhoarntsje hat de IUCN-status fan "net bedrige", om't er yn syn ferspriedingsgebiet noch rûnom foarkomt en om't syn populaasje stabyl liket te wêzen.
Der binne 24 erkende ûndersoarten fan it Amerikaanske reade iikhoarntsje:
It Amerikaanske reade iikhoarntsje (Latynske namme: Tamiasciurus hudsonicus) is in sûchdier út it skift fan 'e kjifdieren (Rodentia), de famylje fan 'e iikhoarntsjes (Sciuridae) en it skaai fan 'e Noardamerikaanske reade iikhoarntsjes (Tamiasciurus), dat foarkomt yn in grut part fan Noard-Amearika. Dit bist wurdt pleatslik ek wol it dinne-iikhoarntsje (pine squirrel), de chickaree of de fairydiddle neamd. It Amerikaanske reade iikhoarntsje moat net betizze wurde mei it (gewoane) iikhoarntsje dat ek yn Fryslân foarkomt, en dat ek wol it (Jeropeeske of Jeraziatyske) reade iikhoarntsje neamd wurdt. De wittenskiplike soartenamme hudsonicus ferwiist nei de Hudsonbaai, dêr't it Amerikaanske reade iikhoarntsje yn 1771 foar it earst de soölooch Johann Christian Polycarp Erxleben ûnder eagen kaam.
The American red squirrel (Tamiasciurus hudsonicus) is one of three species of tree squirrels currently classified in the genus Tamiasciurus, known as the pine squirrels (the others are the Douglas squirrel, T. douglasii, and the southwestern red squirrel, T. fremonti). The American red squirrel is variously known as the pine squirrel, North American red squirrel and chickaree. It is also referred to as Hudson's Bay squirrel, as in John James Audubon's work The Viviparous Quadrupeds of North America (hence the species name). The squirrel is a small, 200–250 g (7.1–8.8 oz), diurnal mammal that defends a year-round exclusive territory. It feeds primarily on the seeds of conifer cones, and is widely distributed across North America wherever conifers are common, except on the Pacific coast of the United States, where its cousin, the Douglas squirrel, is found instead.
The squirrel has been expanding its range into hardwood forests.[3]
American red squirrels should not be confused with Eurasian red squirrels (Sciurus vulgaris); since the ranges of these species do not overlap, they are both commonly referred to as "red squirrels" in the areas where they are native. The specific epithet hudsonicus refers to Hudson Bay, Canada, where the species was first catalogued by Erxleben in 1771.[4] A recent phylogeny suggests the squirrels as a family can be divided into five major lineages. Red squirrels (Tamiasciurus) fall within the clade that includes flying squirrels and other tree squirrels (e.g., Sciurus).[5] There are 25 recognized subspecies of red squirrels.[6]
The southwestern red squirrel (T. fremonti) was long considered conspecific with T. hudsonicus, but a 2016 phylogenetic study found it to be a distinct species.[7]
Red squirrels can be easily distinguished from other North American tree squirrels by their smaller size, 28–35 cm (11–14 in) total length (including tail), territorial behavior, and reddish fur with a white venter (underbelly).[6] Red squirrels are somewhat larger than chipmunks.
The Douglas squirrel is morphologically similar to the American red squirrels, but has a rust-colored venter and is restricted to the southwestern coast of British Columbia and in the Pacific Northwest of the United States. The ranges of the American red squirrel and the Douglas squirrel overlap in southern British Columbia, northwestern Washington and eastern Oregon.[8]
American red squirrels are widely distributed across the North American continent. Their range includes: most of Canada, excluding northern areas with no tree cover, the southern half of Alberta and the southwestern coast of British Columbia; the southern half of Alaska; the Rocky Mountains area of the United States, and northern half of the eastern United States.[6][9] American red squirrels are abundant and not of conservation concern throughout much of their range. American red squirrels were introduced on Newfoundland and have lived there in abundance for decades.[10] However, an isolated population of red squirrels in Arizona has experienced considerable declines in population size. In 1987, this portion of the population was listed as an endangered species.[11]
American red squirrels are primarily granivores, but incorporate other food items into their diets opportunistically.[6] In Yukon, extensive behavioral observations suggest white spruce seeds (Picea glauca) comprise more than 50% of a red squirrel's diet, but squirrels have also been observed eating spruce buds and needles, mushrooms, willow (Salix sp.) leaves, poplar (Populus sp.) buds and catkins, bearberry (Arctostaphylos sp.) flowers and berries, and animal material such as bird eggs or even snowshoe hare leverets (young).[12] White spruce cones mature in late July and are harvested by red squirrels in August and September. These harvested cones are stored in a central cache and provide energy and nutrients for survival over the winter and reproduction the following spring. The fallen scales from consumed seed cones can collect in piles, called middens, up to twelve meters across.[13] White spruce exhibits two- to six-year masting cycles, where a year of superabundant cone production (mast year)[14] is followed by several years in which few cones are produced.[15] American red squirrel territories may contain one or several middens.
American red squirrels eat a variety of mushroom species, including some that are deadly to humans.[16]
American red squirrels are spontaneous ovulators.[17][18] Females enter estrus for only one day, but venture from their territory prior to ovulation, and these exploratory forays may serve to advertise their upcoming estrus. On the day of estrus, females are chased by several males in an extended mating chase. Males compete with one another for the opportunity to mate with the estrous female. Estrous females will mate with 4 to 16 males. Gestation has been reported to range from 31 to 35 days.[19] Females can breed for the first time at one year of age, but some females delay breeding until two years of age or older. Most females produce one litter per year, but in some years reproduction is skipped, while in other years some females breed twice. Litter sizes typically range from one to five, but most litters contain three or four offspring. Offspring are pink and hairless at birth and weigh about 10 g. Offspring grow at approximately 1.8 g per day while nursing, and reach adult body size at 125 days. They first emerge from their natal nests at around 42 days, but continue to nurse until approximately 70 days.
Nests are most commonly constructed of grass in the branches of trees. Nests are also excavated from witches' broom – abnormally dense vegetative growth resulting from a rust disease – or cavities in the trunks of spruce, poplar, and walnut trees. American red squirrels rarely nest below ground. Each individual squirrel has several nests within its territory, and females with young move them between nests. Some behavior has been reported within human dwellings using insulation as nest material.
A three-year study of a population of red squirrels in southwest Yukon reported female red squirrels showed high levels of multiple-male mating and would even mate with males with similar genetic relatedness. The relatedness of parents had no effect on the neonatal mass and growth rate of their offspring, nor did it affect the survival rate of offspring to one year of age.[20]
Red squirrels are highly territorial and asocial with very few non-reproductive physical interactions (0.6% of all recorded behaviours in one 19-year study).[21] The majority of physical interactions are in male-female matings and between females and their offspring before the offspring disperse to their own territories (see Dispersal and survival). The non-reproductive physical interactions recorded were all instances of chasing an intruder from a territory.[21]
If juvenile American red squirrels are to survive their first winter, they must acquire a territory and midden. They can acquire a territory by competing for a vacant territory, creating a new territory or by receiving all or part of a territory from their mothers. This somewhat rare (15% of litters) female behavior is referred to as breeding dispersal or bequeathal, and is a form of maternal investment in offspring.[22] The prevalence of this behavior is related to the abundance of food resources and the age of the mother. In some cases, females will acquire additional middens prior to reproduction, which they later bequeath to their offspring.[23] Offspring that do not receive a midden from their mother typically settle within 150 m (3 territory diameters) of their natal territory.[22] Observations suggest that male red squirrels have environmentally induced, alternative reproductive strategies that result in higher incidences of sexually selected infanticide in years when food is plentiful.[24]
American red squirrels experience severe early mortality (on average only 22% survive to one year of age). The survival probability, however, increases to age three, when it begins to decrease again. Females that survive to one year of age have a life expectancy of 3.5 years and a maximum lifespan of 8 years.[25] Increased maternal attention is correlated with increased offspring growth rate and higher lifetime reproductive success.[26]
Chief predators include Canada lynx (Lynx canadensis), bobcat (Lynx rufus), coyote (Canis latrans), great horned owl (Bubo virginianus), northern goshawk (Accipiter gentilis), red-tailed hawk (Buteo jamaicensis), American crow (Corvus brachyrynchos), American marten (Martes americana), pacific marten (Martes caurina), red fox (Vulpes vulpes), gray fox (Urocyon cinereoargenteus), wolf (Canis lupus), and weasel (Mustela sp.).[27]
_(1).jpg)
{{cite book}}: CS1 maint: multiple names: authors list (link) The American red squirrel (Tamiasciurus hudsonicus) is one of three species of tree squirrels currently classified in the genus Tamiasciurus, known as the pine squirrels (the others are the Douglas squirrel, T. douglasii, and the southwestern red squirrel, T. fremonti). The American red squirrel is variously known as the pine squirrel, North American red squirrel and chickaree. It is also referred to as Hudson's Bay squirrel, as in John James Audubon's work The Viviparous Quadrupeds of North America (hence the species name). The squirrel is a small, 200–250 g (7.1–8.8 oz), diurnal mammal that defends a year-round exclusive territory. It feeds primarily on the seeds of conifer cones, and is widely distributed across North America wherever conifers are common, except on the Pacific coast of the United States, where its cousin, the Douglas squirrel, is found instead.
The squirrel has been expanding its range into hardwood forests.
La ardilla roja americana (Tamiasciurus hudsonicus) es una especie de roedor de la familia de los Sciuridae. Vive en los Estados Unidos y gran parte de Canadá. Se alimenta de semillas, piñas, nueces, fruta y, de vez en cuando, de invertebrados y pequeños vertebrados. Sus hábitats naturales son los bosques de coníferas, mixtos o caducifolios, así como las zonas con vegetación secundaria. Se cree que no hay ninguna amenaza significativa para la supervivencia de esta especie.[3]
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Datos: Q326976
Multimedia:
Especies: Tamiasciurus hudsonicus
La ardilla roja americana (Tamiasciurus hudsonicus) es una especie de roedor de la familia de los Sciuridae. Vive en los Estados Unidos y gran parte de Canadá. Se alimenta de semillas, piñas, nueces, fruta y, de vez en cuando, de invertebrados y pequeños vertebrados. Sus hábitats naturales son los bosques de coníferas, mixtos o caducifolios, así como las zonas con vegetación secundaria. Se cree que no hay ninguna amenaza significativa para la supervivencia de esta especie.
Tamiasciurus hudsonicus Tamiasciurus generoko animalia da. Karraskarien barruko Sciurinae azpifamilia eta Sciuridae familian sailkatuta dago.
Tamiasciurus hudsonicus Tamiasciurus generoko animalia da. Karraskarien barruko Sciurinae azpifamilia eta Sciuridae familian sailkatuta dago.
Punaorava (Tamiasciurus hudsonicus) on Pohjois-Amerikan pohjoisosissa elävä pienikokoinen oravalaji.[2][4] Se on yksi laajimmalle levinneistä ja reviiritietoisimmista oravalajeista Pohjois-Amerikassa.[1][2]
Punaoravalla on solakka ja jäntevä ruumis, voimakkaat takajalat ja vahvat kynnet, joiden ansiosta se on taitava kiipeilemään puissa. Se painaa tavallisesti 140–250 grammaa. Kokonaispituus kuonosta hännänpäähän on 28–35 senttimetriä, josta hännän osuus on 9,5–15 senttimetriä. Häntä ei ole yhtä tuuhea kuin muilla pohjoisamerikkalaisilla oravalajeilla.[2]
Punaoravan väritys vaihtelee suuresti paitsi yksilöittäin, myös elinympäristön ja vuodenajan mukaan. Turkki on selästä ruskehtava tai punaruskea ja vatsasta valkoinen tai vaaleankeltainen. Kesällä vatsa- ja selkäpuolta erottaa toisistaan molemmissa kyljissä kulkeva tumma juova. Suuria, mustia silmiä ympäröivät valkoiset renkaat ja myös hännässä on usein valkoinen reunus.[2]
Punaorava elää Pohjois-Amerikan nearktiselta alueella, missä se on eräs laajimmalle levinneistä oravalajeista.[2] Sen levinneisyysalue ulottuu Alaskasta koko Kanadan halki Koillis-Yhdysvaltoihin ja Appalakkien vuoristoa pitkin Tennesseehen asti. Sitä tavataan myös Kalliovuorilla New Mexicon korkeudelle asti.[2][4] Punaoravasta on sen levinneisyysalueella määritetty 24 eri alalajia[3].
Punaorava viihtyy niin havu-, lehti- kuin sekametsissäkin. Sitä tavataan myös metsäisillä esikaupunkialueilla.[2]
Punaorava on yksin elävä päiväeläin, joka ei nuku talviunta. Aktiivisimmillaan se on kaksi tuntia auringonnousun jälkeen ja juuri ennen auringonlaskua. Se pesii vanhassa tikankolossa, ontossa puussa tai jossakin muussa elinalueellaan sijaitsevassa onkalossa. Jos sopivaa koloa ei löydy, se rakentaa pesänsä korkealle oksanhaaraan ruohoista ja lehdistä.[2][4]
Punaoravan elinalueen koko vaihtelee yksilön sukupuolen, iän ja ympäristön mukaan; yleensä sen pinta-ala on 1–2,4 hehtaaria.[2][4] Jos ravinto alkaa käydä vähiin, punaorava etsii itselleen uuden elinalueen. Etsiessään uutta elinaluetta se voi ylittää myös vesistöjä, sillä se on taitava uimari.[2] Levinneisyysalueensa pohjoisosissa se kaivaa talvisin lumeen käytäväverkostoja.[2][4]
Punaoravalla on erinomainen haju-, näkö- ja kuuloaisti. Se ääntelee paljon ja rähisee äänekkäästi reviirilleen tunkeutuville lajitovereille. Se pakenee saalistajiaan tiheikköihin tai puihin ja puolustautuu uhattuna sisukkaasti.[2]
Punaorava on promiskuiteettinen laji – sekä urokset että naaraat parittelevat usean kumppanin kanssa.[4] Lauhkeassa ilmastossa sillä on kaksi lisääntymiskautta, joista ensimmäinen sijoittuu lopputalveen ja toinen keskikesään. Kylmässä ilmastossa on vain yksi lisääntymiskausi kevätalvella. Tiineys kestää 33–35 vuorokautta, minkä jälkeen naaras synnyttää pesäänsä tavallisimmin 4 tai 5 sokeaa ja karvatonta poikasta, jotka painavat keskimäärin 7 grammaa. Poikaset kasvavat nopeasti ja vieroittuvat emostaan 7–8 viikon kuluttua syntymästä. Ne jättävät pesän 12–14 viikon ikäisinä ja lähtevät emonsa reviiriltä omille teilleen syntymänsä jälkeisenä syksynä.[2][4]
Poikaskuolleisuus on punaoravalla hyvin korkea: vain neljäosa poikasista selviää yhden vuoden ikäiseksi, jolloin ne saavuttavat täysikasvuisuuden ja sukukypsyyden.[2] Elinikä on luonnossa enimmillään 10 vuotta.[4] Punaoravan tavallisimpia saalistajia ovat pöllöt, haukat, kärpät, käärmeet, ketut, punailvekset, kanadanilvekset ja amerikannäädät.[2]
Punaorava on lähes kaikkiruokainen. Se käyttää ravinnokseen enimmäkseen havupuiden siemeniä, mutta myös muita siemeniä, hedelmiä, pähkinöitä, kaarnaa, silmuja, hirvieläinten pudottamia jättösarvia, matelijoita, hyönteisiä, mahlaa, männynkäpyjä, sieniä (myös ihmiselle myrkyllisiä sieniä), munia, linnunpoikasia, hiiriä ja jäniksenpoikasia.[2]
Punaorava varastoi siemeniä ja pähkinöitä talven varalle maan, lehtikasojen ja kivien alle. Tarkan hajuaistinsa avulla se pystyy paikallistamaan ruokakätkön 30 senttimetrin syvyydestä maan alta ja 4 metrin syvyydestä lumen alta. Siemeniä jää kuitenkin paljon myös maahan, minkä vuoksi punaoravalla on suuri merkitys puiden leviämiselle.[2]
Kanadassa metsästetään joka vuosi 1–3 miljoonaa punaoravaa, joiden turkisten arvo on yhteensä noin miljoona dollaria. Tästä huolimatta laji on runsaslukuinen ja elinvoimainen lähes koko elinalueellaan. Kaakkois-Arizonassa sijaitsevalla Mount Grahamilla elävä alalaji T. h. grahamensis on kuitenkin äärimmäisen uhanalainen, ja sen kanta on enää noin 150 yksilöä. Sen elinympäristöä uhkaavat jatkuvat metsänhakkuut ja vuorelle rakennettu observatorio ja leirintäalue.[2]
Punaoravasta on sekä haittaa että hyötyä puiden lisääntymiselle. Se levittää puiden siemeniä ja niille hyödyllisiä sieni-itiöitä. Toisaalta se saattaa syödä havupuiden siemensadosta jopa kaksi kolmasosaa ja aiheuttaa huomattavia vahinkoja puuviljelmille ja siemenvarastoille. Joskus se voi myös kotiutua asuinrakennukseen ja jyrsiä kodin rakenteita tai aiheuttaa muuta tuhoa.[2]
Punaorava (Tamiasciurus hudsonicus) on Pohjois-Amerikan pohjoisosissa elävä pienikokoinen oravalaji. Se on yksi laajimmalle levinneistä ja reviiritietoisimmista oravalajeista Pohjois-Amerikassa.
Tamiasciurus hudsonicus
L'Écureuil roux américain (Tamiasciurus hudsonicus) est une espèce d'écureuils présente au Canada et aux États-Unis.
Sa longueur est de 28 à 35 cm et il pèse entre 140 et 250g. On le remarque à sa couleur qui est blanc sur son ventre et son dos est plus ou moins roux avec une ligne noire séparant le tout. Il est aussi agile et nerveux.
Il ne faut pas le confondre avec l'écureuil roux d'Eurasie (Sciurus vulgaris).
L'écureuil roux d'Amérique du Nord est largement répandu à travers le continent nord américain. Son aire de répartition couvre une grande partie du Canada ainsi que plusieurs états américains.
Bien que cet écureuil vive en solitaire, une équipe de chercheurs canadiens (Kluane Red Squirrel Project) a constaté plusieurs cas d’adoptions de petits orphelins[1]. Étonnamment les orphelins adoptés avaient tous un lien de parenté assez proche avec leur mère adoptive, qui était leur tante, leur sœur ou leur grand-mère, ce qui implique que les écureuils roux connaissent les liens de parentés avec les autres écureuils qui les entourent.
Les chercheurs supposent que ces rongeurs, qui fréquentent peu leurs congénères, reconnaissent les individus à leurs cris et que, lorsqu’un cri familier ne se fait plus entendre, ils vont voir ce qu’il est advenu de la portée.
Comme son cousin européen Sciurus vulgaris, Tamiasciurus hudsonicus consomme en automne et hiver (et peut-être en été) des champignons, dont des champignons hypogés, c'est-à-dire dont la fructification est souterraine. Ce faisant, cette espèce contribue à en disséminer les spores et joue un rôle utile pour la forêt, car ce sont des champignons mycorhiziens essentiels pour des essences forestières majeurs. Elle contribue donc indirectement à la bonne mycorhization des arbres mais aussi à la dispersion des truffes et d'autres champignons.
Une étude[2] a porté sur le contenus du tractus digestif de 75 écureuils roux nord-américains et de 138 Grands Polatouches (Glaucomys sabrinus) capturés de novembre à février en forêt boréale au nord-ouest de l'Alberta. De grandes quantités spores de champignons épigés ont été observées, principalement des spores de Bolétales, Russulaceae et Cortinariaceae. Des spores d'ascomycètes hypogés (Elaphomyces et Tuber sp.) et de basidiomycètes (Gautiera, Hymenogaster, Hysterangium et Rhizopogon sp.) ont également été trouvées dans le tube digestif, en moindre quantité. Moins souvent on a trouvé des restes de sporocarpes coriaces ou carbonacés venant espèces d'Hymenochaetaless, Diatrypaceae, Xylariaceae et Bankeraceae, ainsi que quelques spores de rouilles (e.g. Phragmidium fusiforme) avec des conidies (e.g., Helicoma sp.) et des ascospores de microfungi ascomycètes (e.g. Sordariaceae). Par contre, aucun tissu lichénique n'a pu être trouvé, alors qu'une hypothèse admise était que ces écureuils pouvaient trouver avec les lichens abondants au sol et sur les arbres un complément alimentaire hivernal. Dans la même étude, 110 fumées fécales (excréments) d'écureuil volant du nord ont été collectées dans la même zone de juin à août. Leur analyse a montré que cet écureuil consomme aussi une importante quantité de champignons en été.
Selon MSW :
Tamiasciurus hudsonicus
L'Écureuil roux américain (Tamiasciurus hudsonicus) est une espèce d'écureuils présente au Canada et aux États-Unis.
Lo scoiattolo rosso (Tamiasciurus hudsonicus Erxleben, 1777) è una specie di scoiattolo arboricolo del genere Tamiasciurus originaria del Nordamerica.
Attualmente, gli studiosi riconoscono 24 sottospecie di scoiattolo rosso americano[3][4][5]:
Lo scoiattolo rosso è noto per il grido di richiamo che emette ogni qualvolta è disturbato: un acuto e prolungato ciurr-ciurr. La lunghezza della testa e del corpo insieme varia da 16,5 a 23 cm ed è dunque 2/3 delle dimensioni dello scoiattolo grigio orientale (Sciurus carolinensis)[3][4]. Il mantello varia dal bruno-fulvo al brunastro con una striscia rossastra che, partendo dalle orecchie, arriva fino alla punta della coda, e una linea nerastra lungo i fianchi; gli occhi sono cerchiati di bianco[3][4][6][7]. La coda è rivestita di peli gialli oppure bianchi, mentre le parti ventrali sono bianche[3][4][7]. D'inverno, il colore del mantello sbiadisce e la linea nera laterale, già assente negli individui giovani, sparisce, mentre le orecchie vengono protette da piccoli ciuffi di peli neri e rossastri[3][7]. Una specie molto simile, lo scoiattolo di Douglas (Tamiasciurus douglasii), si differenzia dallo scoiattolo rosso per la sfumatura color ruggine delle regioni ventrali[3][4][6][7].
Lo scoiattolo rosso occupa un areale molto vasto, che dall'Alaska e dal Québec si spinge a sud, attraverso le Montagne Rocciose, fino al Nuovo Messico e, attraverso gli Appalachi, fino alla Carolina del Sud[2][3][5][6][7]. È stato introdotto anche sull'isola di Terranova, presso la costa orientale del Canada[2]. La sottospecie T. h. grahamensis, isolata da tutte le altre, è ristretta al monte Graham, una vetta dei monti Pinaleño, nel sud-est dell'Arizona[2][4][5][6].
Gli scoiattoli rossi vivono essenzialmente nelle foreste decidue e sempreverdi, ma hanno una gran capacità di adattamento, per cui costruiscono la loro tana in qualsiasi riparo, attorno alle case, nelle siepi e nel sottosuolo[3]. Scavano gallerie anche sotto la neve e si servono persino di quelle abbandonate dalle marmotte e dai tamia[3]. Grazie alla loro capacità di adattamento a vivere sottoterra o sotto mucchi di pietre o di legname sono riusciti a sopravvivere al massiccio disboscamento delle foreste che ha ridotto l'ambiente vitale degli scoiattoli prettamente arboricoli[3].
I nidi vengono costruiti sulle biforcazioni dei rami, tra le foglie, nelle tane dei picchi, nelle cavità naturali dei vecchi alberi, nel sottosuolo, nel terreno asciutto o anche sotto pietre e ceppi[3]. Occasionalmente gli scoiattoli rossi si servono anche di vecchi nidi di corvi e di falchi come fondamenta per i loro nidi. Questi sono composti di tre strati: all'esterno da un intreccio di ramoscelli che portano ancora attaccate le foglie, all'interno da uno strato compatto di foglie pressoché impermeabile, mentre la camera interna, grande 10–15 cm, è rivestita di materiale più fine quale erba secca, muschio, penne e peli.
Gli scoiattoli rossi sono animali diurni, ma approfittano anche delle notti di luna per uscire all'aperto e sono laboriosi durante tutto l'inverno, rimanendo nei loro nidi solo durante il maltempo[3].
Gli scoiattoli rossi fanno un grande spreco di cibo, danneggiando e rifiutando più di quanto non ne mangino, e conservandone più di quanto ne possano consumare. La loro dieta è essenzialmente vegetariana con le pigne di pino che costituiscono la base della loro alimentazione durante tutto l'anno[3]. Essi le raccolgono dai rami in autunno, quando sono ancora verdi, e prima che possano maturare e cadere lontano[3]. In seguito le trasportano giù dall'albero e le immagazzinano a gruppi di 150, o anche più, sotto il suolo umido in modo che non possano maturare prima del necessario. Anche altri semi, quali nocciole e bacche, rientrano tuttavia nella loro dieta; a primavera, quando le gemme dell'olmo e dell'acero si staccano, gli scoiattoli rossi ne spaccano la corteccia per succhiarne il succo, così come spaccano le mele per mangiarne i semi, lasciando invece intatta la polpa[3]. Sono anche ghiotti di funghi e spesso li conservano fino a seccarli nelle spaccature degli alberi e nei ceppi[3]. Si nutrono anche della letale Amanita muscaria, dato che sembrano immuni al suo veleno[3]. Infine, ultime fra le loro preferenze sono la corteccia del pioppo comune e del pioppo tremulo, di cui si nutrono nei periodi di carestia, durante i quali non disdegnano altri alimenti vegetali e persino insetti, come ad esempio larve di scarafaggi snidate dal legno, carne putrefatta e, occasionalmente uova e uccellini e, talvolta, uccidono e mangiano persino i piccoli di alcuni conigli[3].
Il corteggiamento inizia in primavera e talvolta fin dal mese di gennaio[3]. Al pari di altri scoiattoli, la caccia nuziale consiste in una gara in cui diversi scoiattoli rossi si inseguono su e giù per gli alberi e sul terreno, lanciando ognuno un richiamo sincopato, dolce e monotono. In seguito si uniscono e l'accoppiamento avviene in marzo o aprile a seconda delle condizioni ambientali[3]. Il maschio e la femmina collaborano alla costruzione del nido ma, completatolo, il primo non partecipa più alla vita familiare.
I piccoli, 4 o 5 in media per nidiata, partoriti dopo un periodo di gestazione di 40 giorni, sono ciechi e completamente privi di peluria, che spunta solo dopo una decina di giorni[3]. Vengono nutriti per cinque settimane e poi vengono cacciati via dalla madre che avrà una seconda nidiata in autunno.
Linci rosse, visoni, falchi adulti e gufi catturano facilmente gli scoiattoli rossi, ma i loro veri nemici sono le martore americane che, in alcune zone, si nutrono quasi esclusivamente di scoiattoli rossi[3]. Infatti si arrampicano con la stessa abilità degli scoiattoli e li inseguono a balzi lungo i rami più sottili degli alberi.
La penuria di animali da pelliccia in molte zone ha provocato un incremento della caccia agli scoiattoli rossi, il cui manto viene utilizzato come guarnizione[3].
Lo scoiattolo rosso è una specie ampiamente diffusa e comune che non sembra correre alcun rischio di estinzione[2]. In alcune aree, la specie può causare danni alle piantagioni di conifere, dal momento che ne strappa la corteccia e si nutre di gemme e semi, sebbene possa anche giocare un ruolo importante nel rimboschimento disperdendo e sotterrando i semi. In Canada, è una delle specie più cacciate per la pelliccia[3][6][7].
Tuttavia, sebbene nella sua interezza la specie non sia attualmente minacciata, la sottospecie del monte Graham è costituita solamente da una popolazione esigua, stimata nel 2009 a circa 250 esemplari[8], tutti relegati in un'unica area isolata[2][5][7]. Ritenuto estinto negli anni '50, lo scoiattolo rosso del monte Graham venne riscoperto negli anni '70[4], ma negli ultimi decenni il suo areale e la sua popolazione si sono ridotti sempre più[9]. La principale minaccia per questa sottospecie è costituita dalla perdita e dalla frammentazione dell'habitat dovuta alla raccolta del legname, allo sviluppo di reti stradali e di strutture turistiche, e dalla costruzione di un controverso complesso di osservatori[2][4][5][7][8], mentre siccità, incendi ed esplosioni di insetti possono solo peggiorare una situazione già compromessa[10][11]. La perdita dell'habitat potrebbe inoltre comportare la competizione con lo scoiattolo di Abert (Sciurus aberti), introdotto nella zona[5][10], e si teme che i mutamenti climatici possano ridurre ulteriormente l'habitat disponibile[10].
Lo scoiattolo rosso (Tamiasciurus hudsonicus Erxleben, 1777) è una specie di scoiattolo arboricolo del genere Tamiasciurus originaria del Nordamerica.
De Amerikaanse rode eekhoorn (Tamiasciurus hudsonicus) is een zoogdier uit de familie van de eekhoorns (Sciuridae). De wetenschappelijke naam van de soort werd voor het eerst geldig gepubliceerd door Erxleben in 1777.
De soort komt voor in Canada en de Verenigde Staten. In 2015 werden enkele individuen ook in België waargenomen, waar ze van nature niet voorkomen.[2][3]
Bronnen, noten en/of referentiesDe Amerikaanse rode eekhoorn (Tamiasciurus hudsonicus) is een zoogdier uit de familie van de eekhoorns (Sciuridae). De wetenschappelijke naam van de soort werd voor het eerst geldig gepubliceerd door Erxleben in 1777.
Sosnowiórka czerwona[3] (Tamiasciurus hudsonicus) – gatunek gryzonia z rodziny wiewiórkowatych[4] występujący w niemal całej Ameryce Północnej – od Alaski, przez Kanadę (aż do wybrzeży Atlantyku w Quebecu oraz Nowej Fundlandii i Labradorze) po Arizonę i Nowy Meksyk na południu oraz Georgię na południowym wschodzie Stanów Zjednoczonych[2].
Czerwono-brązowe futro z białym brzuchem.
Dzienny tryb życia, żyje samotnie w lasach iglastych. Żywi się roślinami, nasionami a także, jajami, małymi ptakami i ssakami.
Obejmuje 24 podgatunki. W Czerwonej księdze gatunków zagrożonych Międzynarodowej Unii Ochrony Przyrody i Jej Zasobów gatunek ten został zaliczony do kategorii LC (najmniejszej troski). Nie ma poważniejszych zagrożeń dla populacji tego gatunku[2].
Wyróżnione podgatunki T. hudsonicus[4]
Sosnowiórka czerwona (Tamiasciurus hudsonicus) – gatunek gryzonia z rodziny wiewiórkowatych występujący w niemal całej Ameryce Północnej – od Alaski, przez Kanadę (aż do wybrzeży Atlantyku w Quebecu oraz Nowej Fundlandii i Labradorze) po Arizonę i Nowy Meksyk na południu oraz Georgię na południowym wschodzie Stanów Zjednoczonych.
Tamiasciurus hudsonicus, o esquilo-vermelho-americano, é uma das três espécies de esquilos de atualmente classificadas no gênero Tamiasciurus. São animais de médio porte (200 a 250 gramas), mamíferos diurnos que defendem um território exclusivo durante todo o ano. A dieta destes esquilos é especializada em sementes de coníferas. Como tal, eles estão amplamente distribuídos entre a América do Norte onde as coníferas são comuns, exceto na costa do Pacífico.[1]
Tamiasciurus hudsonicus, o esquilo-vermelho-americano, é uma das três espécies de esquilos de atualmente classificadas no gênero Tamiasciurus. São animais de médio porte (200 a 250 gramas), mamíferos diurnos que defendem um território exclusivo durante todo o ano. A dieta destes esquilos é especializada em sementes de coníferas. Como tal, eles estão amplamente distribuídos entre a América do Norte onde as coníferas são comuns, exceto na costa do Pacífico.
Amerikansk röd ekorre (Tamiasciurus hudsonicus[2][3][4][5][6][7]) är en däggdjursart som först beskrevs av Johann Christian Polycarp Erxleben 1777. Den ingår i släktet Tamiasciurus och familjen ekorrar.[8][9] IUCN kategoriserar arten globalt som livskraftig.[1]
Arten liknar den europeiska ekorren (Sciurus vulgaris) i utseende men den är tydlig mindre och dessutom tillhör de olika släkten. Individer av amerikansk röd ekorre når en kroppslängd (huvud och bål) av 16,5 till 23 cm, en svanslängd av 9 till 16 cm och en vikt av 195 till 280 gram.[10] Pälsens färg på ryggen varierar mellan rödbrun och brun medan buken är vitaktig. Under sommaren är kanten mellan den bruna och den vita pälsen ofta svartaktig. Den gulgråa till rödbruna svansen är inte lika yvig som hos andra arter av släktet Tamiasciurus. Kring ögonen har arten en iögonfallande vit ring.[10]
Amerikansk röd ekorre förekommer i stora delar av Nordamerika från Alaska över Kanadas tempererade delar till Stora slätterna i USA och östra USA. I centrala USA sträcker sig utbredningsområdet söderut till Arizona och New Mexico. I östra USA ligger utbredningsområdets södra gräns i nordvästra Georgia och södra Virginia.[1]
Arten vistas främst i barrskogar men den hittas likaså i blandskogar, buskskogar och urbaniserade områden.[1]
Individerna är aktiva på dagen. På natten vilar de i trädens håligheter, självbyggda bon av blad eller i jordhålor.[1] Vid sämre väderförhållanden blir ekorren slö men den håller ingen vinterdvala. Den samlar vanligen ett stort förråd för dessa tider och ofta används förrådet av flera generationer. Utanför parningstiden lever varje individ ensam och försvarar ett revir kring förrådet.[10]
Amerikansk röd ekorre äter främst frön från kottar samt andra växtdelar som nötter, bark, sav, nektar, blommor och unga växtskott. Denna kost kompletteras med insekter, fågelägg samt mindre ofta med små ryggradsdjur som småfåglar och andra gnagare.[10]
Honorna parar sig vanligen under våren (februari till april) och ibland även under sensommaren (juni – augusti). En hona parar sig oftast med flera hannar. Dräktigheten varar 31 till 35 dagar och sedan föds 3 till 5 ungar. Ungdjuren är vid födelsen nakna. De får di under cirka 7 till 8 veckor och blir självständiga efter ungefär 18 veckor. Ibland lämnar modern i stället för ungarna reviret när ungarna är tillräckligt stora. De flesta individer blir 3 till 7 år gamla och vissa exemplar blir 10 år gamla.[10]
Arten delas av Catalogue of Life in i följande 25 underarter:[8]
Wilson & Reeder (2005) räknar inte in T. h. columbiensis.[5]
Wikimedia Commons har media som rör Amerikansk röd ekorre.
Wikispecies har information om Tamiasciurus hudsonicus.
Amerikansk röd ekorre (Tamiasciurus hudsonicus) är en däggdjursart som först beskrevs av Johann Christian Polycarp Erxleben 1777. Den ingår i släktet Tamiasciurus och familjen ekorrar. IUCN kategoriserar arten globalt som livskraftig.
Amerika kızıl cincabı (Tamiasciurus hudsonicus), sincapgiller familyasından, Kanada ve Amerika Birleşik Devletleri'ninde daha çok Rocky Dağlarında yaşayan, kozalak tohumlarıyla beslenmeye özelleşmiş, gündüzcül bir sincap türü.
Amerika kızıl sincapları Kanada vaşağı (Lynx canadensis), doru vaşak (Lynx rufus), kır kurdu (Canis latrans), Amerika puhusu (Bubo virginianus), bayağı çakır kuşu (Accipiter gentilis), kızıl kuyruklu şahin (Buteo jamaicensis), Amerika kargası (Corvus brachyrynchos), Amerika sansarı (Martes americana), kızıl tilki (Vulpes vulpes), boz tilki (Urocyon cinereoargenteus), boz kurt (Canis lupus) ve gelincik (Mustela sp.) trürleri tarafından avlanır.
Amerika kızıl cincabı (Tamiasciurus hudsonicus), sincapgiller familyasından, Kanada ve Amerika Birleşik Devletleri'ninde daha çok Rocky Dağlarında yaşayan, kozalak tohumlarıyla beslenmeye özelleşmiş, gündüzcül bir sincap türü.
Країни поширення: Канада (Альберта, Британська Колумбія, Лабрадор, Манітоба, Нью-Брансвік, Північно-Західні території, Нова Шотландія, Нунавут, Онтаріо, Острів Принца Едварда, Квебек, Саскачеван, Юкон), США (Аляска, Аризона, Колорадо, Коннектикут, Делавер, район Колумбія, Джорджія, Айдахо, Іллінойс, Індіана, Айова, Кентуккі, Мен, Меріленд, Массачусетс, Мічиган, Міннесота, Монтана, Нью-Гемпшир, Нью-Джерсі, Нью-Мексико, Нью Йорк, Північна Кароліна, Північна Дакота, Огайо, Орегон, Пенсильванія , Род-Айленд, Південна Кароліна, Південна Дакота, Теннессі, Юта, Вермонт, Вірджинія, Вашингтон, Західна Вірджинія, Вісконсин, Вайомінг). Віддає перевагу хвойним та змішаним лісам, але зустрічається й у листяних лісах.
Живе поодинці. Віддає перевагу гніздуванню в дуплах дерев, а також будує листяні гнізда і використовує земляні нори. Вагітність триває 31-35 днів. Деякі самиці дають два приплоди на рік, в середньому 4-5 дитинчат у виводку. Раціон складається з насіння, хвойних шишок, горіхів, фруктів. Іноді живиться безхребетними і дрібними хребетними. Зазвичай запасає, а потім споживає, велику кількість їжі. Досить активні протягом дня. Піки денної активності через дві години після сходу сонця і за дві години до заходу.
Має червонувато-коричневе хутро на спині, з білим черевом. Довжина тіла 17-23 см, довжина хвоста 9-16 см, вуха 2—3 см, вага 197-282 гр. Зубна формула: 1/1, 0/0, 1-2/1, 3/3, загалом 20, дуже рідко 22 зуба. 2n=46.
Tamiasciurus hudsonicus là một loài động vật có vú trong họ Sóc, bộ Gặm nhấm. Loài này được Erxleben mô tả năm 1777.[2]
Tamiasciurus hudsonicus là một loài động vật có vú trong họ Sóc, bộ Gặm nhấm. Loài này được Erxleben mô tả năm 1777.
Tamiasciurus hudsonicus (Erxleben, 1777)
Подвиды[1]
Красная белка[2] (лат. Tamiasciurus hudsonicus) — вид грызунов семейства беличьих, наиболее распространённый и характерный представитель рода красных белок. Научное видовое название «hudsonicus» дано животному в честь Гудзонова залива, места, в котором оно было впервые описано[3].
Распространён практически по всей территории Северной Америки — на Аляске, в Канаде, в США вплоть до пустынь Аризоны и Нью-Мексико на юге и Джорджии на юго-востоке[4]. Белки населяют различные лесистые местности, в том числе хвойные, лиственные и смешанные леса. Также их можно наблюдать в пригородных районах, где имеются насаждения из больших зрелых деревьев[5].
Длина тела белок 28—35 см, длина хвоста — 9,5—15 см. Окрас меха очень изменчив[5]. В разных регионах своего ареала эти белки могут иметь вариабельный окрас[5], а также белки меняют мех на зимний и летний[3][5]. Мех обычно коричневатый или оливково-красный. Летом по бокам есть чёрная продольная полоса, которая разделяет живот и спину. Мех на животе белый или кремовый. Хвост обычно имеет белую кайму. Вокруг чёрных глаз мех белый[5].
В дикой природе красные белки живут до семи лет, но большинство погибают прежде, чем доживут до года. Ведут одиночный и дневной образ жизни; активны круглый год. Активнее всего на рассвете и после полудня. Своё логово размещают в старых дуплах дятлов, древесных пустотах или других мелких расщелинах. На севере ареала красные белки зиму часто проводят в подземной системе тоннелей. Белки часто мигрируют если запас пищи на проживаемой территории снижается. Мигрируя, им часто приходится переплывать водоёмы[5].
Красная белка — один из отрицательных персонажей мультсериала Пингвины из Мадагаскара.
Красная белка Чиву (Chewoo) - один из главных персонажей мультсериала "Юху и его друзья" (YooHoo & Friends)
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Это заготовка статьи о грызунах. Вы можете помочь проекту, дополнив её. Красная белка (лат. Tamiasciurus hudsonicus) — вид грызунов семейства беличьих, наиболее распространённый и характерный представитель рода красных белок. Научное видовое название «hudsonicus» дано животному в честь Гудзонова залива, места, в котором оно было впервые описано.
北美紅松鼠（學名：Tamiasciurus hudsonicus）是美洲紅松鼠的其中一種。
北美紅松鼠（學名：Tamiasciurus hudsonicus）是美洲紅松鼠的其中一種。
아메리카붉은다람쥐 또는 아메리카붉은청서(영어: American red squirrel, Tamiasciurus hudsonicus)는 다람쥐과에 속하는 설치류의 일종이다.[2] 타미아스키우루스속에 속하는 3종의 나무 다람쥐의 하나로 나머지 종은 더글라스다람쥐청서와 먼스다람쥐청서이다. 몸무게 200~250g의 중형 크기의 청서류로 낮에 활동하는 주행성 포유류이다. 일년 내내 독점적인 영역에서 활동을 한다. 천적은 여우, 캐나다스라소니, 대형맹금류, 뱀이다.
24종의 아종이 알려져 있다.[2]
아메리카붉은다람쥐 또는 아메리카붉은청서(영어: American red squirrel, Tamiasciurus hudsonicus)는 다람쥐과에 속하는 설치류의 일종이다. 타미아스키우루스속에 속하는 3종의 나무 다람쥐의 하나로 나머지 종은 더글라스다람쥐청서와 먼스다람쥐청서이다. 몸무게 200~250g의 중형 크기의 청서류로 낮에 활동하는 주행성 포유류이다. 일년 내내 독점적인 영역에서 활동을 한다. 천적은 여우, 캐나다스라소니, 대형맹금류, 뱀이다.
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