Grasshopper sparrows eat insects and seeds, with proportions varying seasonally. In the summer, they eat primarily insects, with about 69% of their diet being invertebrates and 39% seeds. In fall they eat mainly seeds, making up 71% of the diet, with 29% made up of invertebrates. Common seeds eaten are sedges (Cyperaceae) and panic grass (Panicum). Preferred insect prey are grasshoppers, mainly species in the genera Xiphidium, Scudderia, Hippiscus, and Melanopus, but especially the grasshopper species Cordillacris occipitalis. They will also eat other insects and spiders, as they are encountered. Grasshopper sparrows forage on the ground using vision to detect prey, so they require open areas and bare ground for good visibility. They capture grasshoppers by pinching them around the thorax, immobilizing them. They will remove hard, less digestible parts, such as legs, before feeding them to offspring.
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: seeds, grains, and nuts
Primary Diet: carnivore (Insectivore ); herbivore (Granivore ); omnivore
Most predation is probably on eggs, nestlings, and fledglings. Grasshopper sparrow adults will perform broken-wing distraction displays near nests or fledglings to draw predators away. They also use alarm calls to signal the presence of a threat. They hide the location of nests by never flying directly to them. Instead they land a short distance away and run through the grass to the nest entrance. Similarly, when leaving, they run from the nest and then take flight at a distance from the nest. Grasshopper sparrows nests are widely dispersed and well-hidden, so predators mostly happen upon them by chance. Eggs and nestlings may be taken by snakes, including blue racers (Coluber constrictor), rat snakes (Elaphe species), common garter snakes (Thamnophis sirtalis), kingsnakes (Lampropeltis species) and pigmy rattlesnakes (Sistrurus miliarus). Mammalian nest predators include striped skunks (Mephitis mephitis), raccoons (Procyon lotor), weasels (Mustela species), ground squirrels (Spermophilus species), foxes (Vulpes species), domestic cats (Felis catus), feral pigs (Sus scrofa), and armadillos (Dasypus novemcinctus). Adults may be taken by various hawks and are regularly preyed on by loggerhead shrikes (Lanius ludovicianus).
Known Predators:
Anti-predator Adaptations: cryptic
Grasshopper sparrows are small sparrows, from 10.8 to 11.5 cm and from 14.5 to 20 g. They have robust bills, flesh colored legs, and streaked black and chestnut brown feathers on their back. Their breast and belly are unstreaked and creamy buff or white. They have a dark crown with a light colored crown stripe and yellowish plumage on the face surrounding the eyes which is disrupted by a dark line extending backwards from the eye. They have a relatively short tail and are considered stockier and bigger-headed than other, sympatric Ammodramus species. The intensity of plumage coloration varies geographically. Males and females are alike and juveniles have streaked breasts.
Grasshopper sparrows may be confused with Henslow's sparrows (Ammodramus henslowii), LeConte's sparrows (Ammodramus leconteii), Nelson's sharp-tailed sparrows (Ammodramus nelsoni), Baird's sparrows (Ammodramus bairdii), and savannah sparrows (Passerculus sandwichensis), although Baird's and savannah sparrows have streaked breasts. The best way to distinguish among Ammodramus sparrows is with their songs, as they are often difficult to observe.
Range mass: 14.5 to 20 g.
Range length: 10.8 to 11.5 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Grasshopper sparrows have an estimated average lifespan of 2.9 years. One individual lived 6.5 years in the wild. Annual survival of adults was estimated at 60%.
Range lifespan
Status: wild: 6.5 (high) years.
Average lifespan
Status: wild: 2.9 years.
Grasshopper sparrows prefer open grasslands with bare ground for foraging. In western, arid grasslands and prairies, grasshopper sparrows tend to be found in areas with shrub cover and more vegetation. In eastern, tallgrass prairies and moist grasslands, they tend to be found in areas of sparse vegetation. They are found in grasslands characterized by a wide variety of plants, including pine savannas, palmetto-sawgrass prairies, lowbush blueberry copses, and bunchgrass prairies. In the Appalachian Mountains these sparrows were once found up to 1550 m elevation on limestone outcroppings and "balds." Grasshopper sparrows seem to prefer areas with broad expanses of suitable habitat, not fragmented areas. Savannah sparrows (Passerculus sandwichensis) are most similar in habitat preferences to grasshopper sparrows. Other species with similar, but not completely overlapping, habitat preferences are Henslow’s sparrows, meadowlarks, bobolinks, and vesper sparrows.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: savanna or grassland
Most grasshopper sparrow populations are migratory, wintering in the southern United States along the coastal plains of Virginia south through Florida, and along the Gulf of Mexico. They also winter throughout most of Mexico and into western Central America. They breed throughout most of the United States east of the Rockies, portions of southern Canada, and isolated populations in the western United States. Breeding is from southern Maine and Quebec to the Carolinas, through central Georgia, Alabama, and Mississippi, northernmost Louisiana, and most of Texas north to throughout most of Montana. They breed as far north in the plains region as southernmost Alberta, Saskatchewan, and Manitoba and throughout the Great Lakes region to southern Ontario. Isolated western populations include an area from southern British Columbia through eastern Washington and Oregon, an area of southern Idaho into northernmost Utah and Nevada, and portions of California, including coastal areas and the Sacramento Valley and western slopes of the Sierra Nevada. There are several populations that are resident year round, including portions of Central America and central Mexico, large parts of Texas, southernmost Arizona, and the central Gulf states, including Florida. They are also found year-round and wintering in the Greater Antilles Islands.
Biogeographic Regions: nearctic (Native )
Savannah sparrows may be dominant over grasshopper sparrows where they co-occur. Grasshopper sparrow nests are sometimes parasitized by brown-headed cowbirds (Molothrus ater). Habitat may influence exposure to nest parasitism, with grasshopper sparrow nests closer to forest edge being more vulnerable. Shiny cowbirds (Molothrus bonariensis) have colonized the Florida range of grasshopper sparrows recently and may parasitize nests.
Grasshopper sparrows are parasitized by nasal mites (Ptilonyssus sairae), Gulf Coast ticks (Amblyoma maculatum), and bird ticks (Haemaphysalis chordeilis).
Commensal/Parasitic Species:
Grasshopper sparrows are a unique element of the native North American grassland fauna.
There are no known adverse effects of grasshopper sparrows on humans.
Grasshopper sparrow populations have been experiencing declines of 3.9% on average throughout the 20th and into the 21st centuries. Declines are mainly the result of loss and fragmentation of grassland habitats, such as native prairies and pastures. Over 99% of native prairies have been converted to agriculture in Wisconsin, Illinois, and Minnesota. They are considered "least concern" by the IUCN because they are widespread and populations remain large, but they are rare in portions of their range. They are considered a species of special concern in Michigan, California, Washington, New York, Massachusetts, and Wyoming. They are considered threatened in New Jersey, threatened as A. s. floridanus in Florida, and endangered in Connecticut. Prescribed burning, grazing, and mowing have been used to improve habitats for grasshopper sparrows in some areas.
Most declines have been documented in the subspecies A. s. pratensis, distributed throughout much of the northeastern United States, and A. s. perpallidus, found in the Pacific states, with declines up to 69% since the 1960's. Ammodramus savannarum pratensis populations have been lost from much of their former New England range. The Florida subspecies, A. s. floridanus, now breeds in a much more restricted area than it did formerly.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: special concern
IUCN Red List of Threatened Species: least concern
Grasshopper sparrows get their common name for the buzzing, insect-like quality of their songs. They are one of the few sparrow species that sings 2 different songs; males sing one song for attracting a mate and another to defend a breeding territory. Their primary song is several staccato notes followed by a sustained, insect-like "zeeeeee" and seems to be mainly territorial. The secondary song is a squeaky set of notes varying in pitch and seems to be used primarily in mate attraction and maintaining the pair bond. Males and females also use a descending trill to communicate with their mate, announcing their presence at the nest. Males also sing a flight song. Songs are sometimes sung together, as in the primary song followed by the secondary song. Songs are generally restricted to the breeding season, with grasshopper sparrows being relatively quiet at other times of the year. They also have a set of calls that are used, most are staccato "chip" or "tsip" notes used to indicate alarm, beg for food, or maintain contact.
Grasshopper sparrows also use a variety of visual displays in communication. Males use a wing-flutter display when singing on a perch. They use this wing-flutter display in antagonistic interactions with other males as well. They will chase other males and maintain a posture with the head below the back to indicate aggression. Females rapidly quiver their wings towards the male as a signal of appeasement or readiness to copulate.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Grasshopper sparrows are considered closely related to South American grassland sparrows (Myospiza humeralis) and yellow-browed sparrows (Myospiza aurifrons).
Grasshopper sparrows are seasonally monogamous, although some polygyny has been described. Pairs are formed on the breeding grounds. Extra pair copulations are not reported, but more study is needed. Males use songs and a fluttering flight display to attract females. Males and females use contact calls throughout the breeding season to maintain the pair bond. Non-parental helpers at the nest are common, in one study 17% of nests had non-parental helpers, who made between 9 and 50% of visits to the nest with food.
Mating System: monogamous ; polygynous ; cooperative breeder
Breeding season length and timing vary among grasshopper sparrow populations. Northern populations breed for about 90 days from May into August. In Florida and Jamaica, grasshopper sparrows breed twice yearly. Other populations breed either once or twice yearly and the timing of breeding varies. Pairs can attempt up to 3 broods in a year, although 2 is more typical. Males arrive on the breeding grounds a few days before females and establish territories. Pairs build nests immediately after forming in northern populations, up to 4 weeks after males begin singing in other populations. Females build cup-like nests on the ground, with a roof of grasses and a side opening. Nests are usually built of grasses, with finer materials lining the interior. New nests are built for each brood. Females lay from 3 to 6 (usually 4 to 5) eggs and incubate them for 11 to 13 days. Young leave the nest at 6 to 9 days old, but they leave the nest by running from it, rather than flying. Young leave the area of the nest immediately after fledging and are cared for to a limited extent by parents for an unknown time after that. Young can breed in the year following their hatching.
Breeding interval: Grasshopper sparrows breed either once or twice yearly, varying with region.
Breeding season: Breeding season varies regionally, from May into August in northern populations, from April to June and October to November in Jamaica, from March through June and then July to September in Florida, and from April to June in Panama and Haiti.
Range eggs per season: 3 to 6.
Average eggs per season: 4-5.
Range time to hatching: 11 to 13 days.
Range fledging age: 6 to 9 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Females incubate the eggs and brood nestlings. Helpers at the nest may also brood nestlings. Young are altricial at hatching, developing their juvenile plumage at 10 to 12 days. Both parents and non-parental helpers at the nest will feed young. Males help to protect young by defending territories and keeping alert for predators. Young leave the nest at 6 to 9 days old and are cared for by parents for an unknown period after that. Based on inter-clutch intervals, this post-fledging care is from 4 to 19 days long. Young gather in small flocks at 3 to 4 weeks after hatching. Some may remain with parents as helpers at the nest.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female); post-independence association with parents
A small (4 ½ inches) sparrow named for its insect-like song, the Grasshopper Sparrow is easy to overlook. Mostly buff-brown streaked with brown above and cream below, this sparrow may be identified from its large head, small body, and pale eye-stripes. Males and females are similar to one another in all seasons, while the juvenile has a streaked breast. The Grasshopper Sparrow breeds across a large portion of the eastern United States and the Great Plains from the Canada border well into the Deep South. There are also isolated breeding areas in the mountain west and along the coast of California. Despite its wide distribution, however, the Grasshopper Sparrow is an uncommon breeder throughout most of its breeding range due to specific habitat requirements. Grasshopper Sparrows migrate south for the winter, where they may be found along the Gulf coast, the coastal southeast, and along the U.S. -Mexico border. The Grasshopper Sparrow inhabits grassland habitats in its breeding and winter ranges. This species prefers grasslands that are drier and more open, with less ground-covering grass litter, than those inhabited by Henslow’s Sparrow (Ammodramus henslowii). In summer, Grasshopper Sparrows eat insects (coincidentally, grasshoppers make up a significant portion of their diet), while in winter, they primarily eat seeds. Grasshopper Sparrows forage on the ground. Like many grassland-dwelling bird species, the Grasshopper Sparrow is best identified by ear, specifically by listening for its insect-like song. Due to its feeding habits and cryptic coloration, Grasshopper Sparrows are difficult to see while at rest, and may be most easily seen while on short flights above the grass.
A small (4 ½ inches) sparrow named for its insect-like song, the Grasshopper Sparrow is easy to overlook. Mostly buff-brown streaked with brown above and cream below, this sparrow may be identified from its large head, small body, and pale eye-stripes. Males and females are similar to one another in all seasons, while the juvenile has a streaked breast. The Grasshopper Sparrow breeds across a large portion of the eastern United States and the Great Plains from the Canada border well into the Deep South. There are also isolated breeding areas in the mountain west and along the coast of California. Despite its wide distribution, however, the Grasshopper Sparrow is an uncommon breeder throughout most of its breeding range due to specific habitat requirements. Grasshopper Sparrows migrate south for the winter, where they may be found along the Gulf coast, the coastal southeast, and along the U.S. -Mexico border. The Grasshopper Sparrow inhabits grassland habitats in its breeding and winter ranges. This species prefers grasslands that are drier and more open, with less ground-covering grass litter, than those inhabited by Henslow’s Sparrow (Ammodramus henslowii). In summer, Grasshopper Sparrows eat insects (coincidentally, grasshoppers make up a significant portion of their diet), while in winter, they primarily eat seeds. Grasshopper Sparrows forage on the ground. Like many grassland-dwelling bird species, the Grasshopper Sparrow is best identified by ear, specifically by listening for its insect-like song. Due to its feeding habits and cryptic coloration, Grasshopper Sparrows are difficult to see while at rest, and may be most easily seen while on short flights above the grass.
The grasshopper sparrow (Ammodramus savannarum) is a small New World sparrow. It belongs to the genus Ammodramus, which contains three species that inhabit grasslands and prairies. Grasshopper sparrows are sometimes found in crop fields and they will readily colonize reclaimed grassland. In the core of their range, grasshopper sparrows are dependent upon large areas of grassland where they avoid trees and shrubs.[2] They seek out heterogenous patches of prairie that contain clumps of dead grass or other vegetation where they conceal their nest, and also contain barer ground where they forage for insects (especially grasshoppers), spiders, and seeds.[3] Grasshopper sparrows are unusual among New World sparrows in that they sing two distinct song types, the prevalence of which varies with the nesting cycle. The primary male song, a high trill preceded by a stereotyped series of short chips, is reminiscent of the sounds of grasshoppers[4] and is the origin of this species' name. Like some other birds of the central North American grasslands, this species also moves around a lot, not only via annual migrations, but individuals frequently disperse between breeding attempts or breeding seasons. Grasshopper sparrows are in steep decline across their range, even in the core of the breeding distribution in the tallgrass prairies of the central Great Plains.[5] The Florida grasshopper sparrow (Ammodramus savannarum floridanus) is highly endangered.
These small sparrows measure 10–14 cm (3.9–5.5 in) in length, span about 17.5 cm (6.9 in) across the wings and weigh from 13.8 to 28.4 g (0.49 to 1.00 oz), with an average of 17 g (0.60 oz).[6][7] Adults have upperparts streaked with brown, grey, black and white; they have a light brown breast, a white belly and a short brown tail. Their face is light brown with a white eye ring and a dark brown crown with a central narrow light stripe. Adults sport bright yellow feathers at the crook of their underwing, and have a yellow-to-amber patch above their lores. Males and females cannot be distinguished by their plumage, and young birds molt into adult plumage within a few months of fledging.[8]
Their breeding habitat is open fields and prairie grasslands across southern Canada, the United States, Mexico and Central America, the Caribbean. There is a small endangered population in the Andes of Colombia and (perhaps only formerly) Ecuador. In the central USA, birds are quick to locate newly available habitat, and can be attracted to sites by playing conspecific song.[9] The spatial distribution of territories on the landscape can be clumped with several individuals defending territories near to one another interspersed by large areas of unused and apparently suitable habitat. The reasons for this clumping are elusive; aggregation is not related to group defense against predators or brood parasite, cooperative care, extra-pair matings, or kin selection.[10] Appropriate habitat is strongly influenced by plant structure and precipitation amounts during previous seasons.[11] Grasshopper sparrows avoid woody vegetation, and in the wetter parts of their range, prefer fields that are burned every 2–3 years (which reduces encroachment of trees and shrubs) and seek out areas that are moderately grazed by cattle or bison.
Subspecies of grasshopper sparrows differ in their migratory behavior. The birds breeding in most of the eastern US and southern Canada (A. s. pratensis) migrate latitudinally up to several thousand kms each year,[12] spending winters along the Gulf of Mexico and the Caribbean.[13] The birds breeding through most of the Western part of their North American range (A. s. perpallidus) winter from Texas west to California, and south into the highland desert grasslands of northern and central Mexico. A. s. ammolegus, which breeds in the desert grasslands of SE Arizona, SW New Mexico, and adjoining states in northern Mexico, appears to be a short-distance, partial migrant, with some birds remaining resident year-round, and others likely moving further south in winter. Birds of multiple breeding populations and subspecies winter together in SE Arizona.[14] Grasshopper sparrows breeding outside of North America, including those living in the Caribbean, Central America, as well as the Florida grasshopper sparrow are not known to migrate.
Males typically migrate north in the spring a week or two earlier than do females. Data from light level geolocators indicate that males are present on the breeding grounds from April to October,[13] consistent with birds completing their annual molt prior to migration.[8] Individuals migrated an average of ~2,500 km over ~30 days.[13] Birds migrate mostly over land, make few stop-overs of short duration, and travel at about 82 km/day.[13] Data from the Motus network largely confirm the migratory patterns gleaned from prior work.[15] However, relatively few movement tracks for this species exist so far, potentially due to the sparrows' secretive behavior during most of the year other than the breeding season.[16] Few recoveries of banded birds have ever been made, especially at sites other than a birds’ initial banding location.[17] In Oklahoma, grasshopper sparrows are one of the species most frequently found dead after colliding with windows, despite rarely being detected in migration.[18]
In Maryland, a study of natal dispersal (the movement from a natal site to the site of first reproduction) revealed that most fledglings remained within their natal habitat during the summer months after fledging, and most recaptured fledglings were encountered within a couple hundred meters of their natal nests.[19] Although distances recaptured from the nest increased with time, the average fledgling was recaptured only 346 meters from its nest and recaptured 33 days after fledging. The longest distance detected was 1.6 kilometers, which was accomplished in less than 20 days.[19] Data on first-year return rates (or "philopatry", the inverse of natal dispersal) is limited, but in NE Kansas, ~2% of young birds returned to the site to breed in the subsequent year.[20]
Grasshopper sparrows are unusual in their particularly high rates of breeding dispersal (i.e., one-way movements between successive breeding sites).[21] Their high dispersal tendency may be due to the dynamic nature of the grassland environments on which they depend[22] Like some other grassland-dependent species, their dispersal movements lead them to be called semi-nomadic, as they opportunistically take advantage of suitable habitats as they appear on the landscape.[23] Return rates of adult grasshopper sparrows to their previous breeding sites (site fidelity) differs widely between populations.[3] Site fidelity is far higher in eastern parts of the breeding range, with>50% of adult males returning to breed in subsequent seasons at a site in Connecticut[24] and over 70% in Maryland.[25] In contrast, 0% of adult males in Nebraska returned to breed in subsequent years,[26] 8.9% returned in Montana,[22] and 20% returned in California.[27] In northeastern Kansas, individual birds also commonly disperse within seasons between nesting attempts.[21] Between 30-75% of birds move over 100 m within season, and individuals were detected defending new territories or nesting up to 8.9 km from areas they occupied earlier in the season.[21] Within-season breeding dispersal decisions relate to nest success; more birds moved following nest failure, and birds that dispersed experienced lower brood parasitism and higher nesting success following movements.[28] Little is known about the movements of birds during winter, but inter-annual variation in abundance in northern Mexican grasslands is positively related to related to broad-scale variation in vegetation, rainfall the previous summer, and plant productivity.[11]
Grasshopper sparrows are a socially monogamous species,[3] but rates of extra-pair mating can be high (e.g., 48.5% of nests contained an extra-pair young in Kansas[10]), and even instances of cooperative parenting[26] have been documented. In the spring, males select and defend territories before being joined by a female. Over the course of the breeding season, birds can raise multiple broods, either with the same mate or a different mate. In the more southern regions of the species range, pairs may produce 2-4 broods while pairs further north are limited by shorter summers leading to 1-2 nesting attempts.[3]
Nest building
Females construct nests over the course of a couple of days.[29] Grasshopper sparrows build inconspicuous, dome-shaped nests on the ground, typically very well hidden amongst grasses and forbs.[30] The nests have a small side opening and are usually made of a mix of dead and live grasses. Nests are built on the breeding pair’s territory in areas away from shrubs and trees.
Offspring
Females typically lay between 4-5 eggs per clutch.[31] Grasshopper sparrow eggs are smooth and oval-shaped. They are a cream-white color, with reddish-brown speckling that is concentrated towards the larger end of the egg.[3] Females incubate the eggs from 10–12 days, and nestlings fledge after 6–9 days.[3] For the first few days of the nestling period, females primarily feed young, but both parents feed during the latter half of the nestling period. In one study, nonparental helpers were documented attending to broods[32] and feeding young, but this behavior is apparently not ubiquitous.[10] Nestlings are fed an arthropod rich diet, particularly prey ~15–40 mm long, and preferentially select acridid grasshoppers, spiders, and small beetles.[33] Upon leaving the nest, the offspring often remain in the area. Parents provide post-fledging care, but the duration and level of care is unknown.
Brood parasitism
Grasshopper sparrows are a common host of the brown-headed cowbird, a brood parasite which lays their eggs in the nests of other species. Cowbirds can be detrimental to host species because they often remove host eggs and nestlings or destroy nests to initiate another nesting attempt, allowing for future parasitism. However, they do not necessarily reduce the chances of nests successfully fledging young. The rate of brood parasitism by brown-headed cowbirds varies across the grasshopper sparrow’s range and depends on habitat characteristics such as the amount of woody vegetation and whether the land is grazed.[34] In surveyed populations, 2-65% of nests were parasitized by cowbirds.[3]
Causes of nest failure
Only 30-50% of nests successfully raise at least one or more nestlings that fledge the nest.[3] The majority of grasshopper sparrow nests fail as the result of predation.[35] Snakes, small mammals such as rats, larger mammals such as skunks, armadillos, hogs, and opossums, and even ants have been observed eating eggs and nestlings.[36] Other causes of nest failure include flooding of the nest cup due to rainfall, trampling by livestock or humans, and abandonment by the parents.[37]
The grasshopper sparrow's "primary" or "buzz" song has one to four introductory notes followed by a long high pitched trill,[38] [39]'tup zeeee' or 'tip tup zeee', and because of its similarity to a grasshopper sound, accounts for the name of the bird.[4] There are small variations in the song between individuals, populations, and subspecies.[38] [39] This song is primarily used for defense, territory, or advertising to the other males and females.[40] The males will mainly use the primary song from mid-April, when they get to the breeding ground, to mid-August, when they are about to leave the breeding grounds.[4] It is the principal song heard early in the season, and during each breeding cycle, and the only song that unpaired birds sing.[39] Birds sing from a grass or forb stalks, poles, fence posts or fence lines, or low shrubs.[4]
Male grasshopper sparrows sing "alternate", warble", or "sustained", songs during the breeding season to establish and maintain pair bonds.[4] The alternate song is more musical than the primary song and is usually delivered from fixed perches or in flight.[41] The song consists of a 5–15 second series of short notes varying slightly in pitch,[42] and the entire sequence may be repeated two to four times.[40] Paired males will start singing alternate song ~5 days after arrival on territory, with frequency of alternate song increasing as birds pair.[4] The alternate song diminishes towards late-July as the breeding season winds down. Considerable variation in alternate song exists within and between populations and subspecies; further study is needed.[39]
The trill of a male grasshopper sparrow (ti-tu-ti-tu-ti-i-i-i-i) is one of his least common vocalizations and is difficult to detect.[38] Sometimes called the nesting song, it consists of short, rapid notes and a downward trill.[38] The song is usually used after two grasshopper sparrows form a pair and is mostly made in response to the female.[38] The male trills near the nest either from the ground or a perch.[38] The male trill functions to strengthen pair bonds and to tell the female/young the male is approaching the nest.[38]
The female trill (ti-ti-i-i-i-i-i) is used to announce presence in male’s territory.[4] The primary functions of the female trill is to declare her presence to the male, maintain the pair bond, and signal to both the male and the young that she is approaching the nest.[41][4] Given the high rate of extra-pair copulations in this species,[10] the trill may also function to announce her presence to a territorial male other than the social male. Females usually call from the ground, concealed in grass, and may call independently or in response to primary or sustained song. Females call from pair formation until the end of nesting.[4]
The call or chip is used by both sexes and is used as an alarm note.[38] Depending on its intensity, the sound varies. High intensity alarms resemble a slow clicking, and low intensity alarms are a sharp 'tik'.[38] The chip is used around the nest by both the female and male using single and double 'chip-chip' calls.[41] This call can be used during feeding when they utter a single, high-pitched chip.[38]
Captive-rearing experiments revealed that grasshopper sparrows are predisposed to learn two distinct songs but must hear species-typical songs to develop a normal sounding song.[40] Grasshopper sparrows can learn song from pre-recorded tutors but are more inclined to learn songs that are similar to live tutors, suggesting they use information from song models but do not directly imitate conspecific song.[40] It is likely that in the case of alternate songs, exact notes are imitated but sequences are invented or improvised.[40] This may be beneficial for pair bonding if females identify individual males by their distinct alternate song.
The global population of grasshopper sparrows in 2016 was estimated to be around 31,000,000 by the PIF North America Landbird Conservation Plan. It was also estimated that the population had undergone a 68% decrease between the years 1970 and 2014 with an annual decline of about 2.59%. The 2022 State of the Birds reported a long-term, range-wide decline of 2.13% per year, and a more recent decline of 3.48% per year.[43] The leading cause of population decline across its range is linked to habitat loss and management, particularly conversion of grasslands to intensive agriculture and encroachment of shrubs and trees. Despite declining population sizes, grasshopper sparrows are classified as Least Concern by the IUCN and are also not included as a "Bird of Conservation Concern" by the U.S. Fish and Wildlife Services (USFWS) on a national level. The Florida grasshopper sparrow subspecies (Ammodramus savannarum floridanus) is classified as endangered by the USFW.[44] This subspecies hit an all time population low of 15 breeding pairs in 2017, and reported a population of 120 in 2022.[45]
The majority of the former breeding range of grasshopper sparrows in North America has been converted to intensive agriculture[46] or encroached by shrubs and trees.[47] Likewise, these birds are experiencing a loss of wintering habitats, particularly within the Chihuahuan grasslands, due to similar impacts (conversion to agriculture and woody encroachment).[48] Because grasshopper sparrows require areas of dense dead grass for nesting, sparse vegetation for foraging, and little to no woody plants, they are vulnerable to management practices such as high-intensity grazing accompanied by annual burning, fire suppression leading to woody encroachment, and haying that can destroy nests if it occurs during the breeding season. Ideal grazing intensities and fire frequencies vary across their range depending on climate, but areas with moderate grazing by cattle or bison, prescribed burning every 2–3 years, and removal of woody plants tend to support the highest densities of grasshopper sparrows in the Southern great plains.[49]
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Grasshopper sparrow
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Grasshopper sparrow flying
Juvenile grasshopper sparrow
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{{cite journal}}: CS1 maint: DOI inactive as of February 2023 (link) The grasshopper sparrow (Ammodramus savannarum) is a small New World sparrow. It belongs to the genus Ammodramus, which contains three species that inhabit grasslands and prairies. Grasshopper sparrows are sometimes found in crop fields and they will readily colonize reclaimed grassland. In the core of their range, grasshopper sparrows are dependent upon large areas of grassland where they avoid trees and shrubs. They seek out heterogenous patches of prairie that contain clumps of dead grass or other vegetation where they conceal their nest, and also contain barer ground where they forage for insects (especially grasshoppers), spiders, and seeds. Grasshopper sparrows are unusual among New World sparrows in that they sing two distinct song types, the prevalence of which varies with the nesting cycle. The primary male song, a high trill preceded by a stereotyped series of short chips, is reminiscent of the sounds of grasshoppers and is the origin of this species' name. Like some other birds of the central North American grasslands, this species also moves around a lot, not only via annual migrations, but individuals frequently disperse between breeding attempts or breeding seasons. Grasshopper sparrows are in steep decline across their range, even in the core of the breeding distribution in the tallgrass prairies of the central Great Plains. The Florida grasshopper sparrow (Ammodramus savannarum floridanus) is highly endangered.
