Atelocynus microtis is native to the northern part of South America and has been found in the Amazon basin regions of Brazil, Peru, Ecuador and Colombia. It has also been sighted in the upper Rio Orinoco basin in Colombia and Venezuela and the upper Rio Parana basin in Mato Grosso, Brazil.
Biogeographic Regions: neotropical (Native )
The Short-eared Dog has been found in scattered sites from Colombia to Bolivia and Ecuador to Brazil. Its presence in Venezuela was suggested by Hershkovitz (1961) but never confirmed. Various studies have suggested the presence of the species throughout the entire Amazonian lowland forest region, as well as Andean foothill forests in Ecuador and Peru up to 2,000 m (Emmons and Feer 1990, 1997; Tirira 1999; A. Plenge pers. comm. 2002).
For the 2004 assessment, museum specimens were re-checked and an extensive survey of field biologists doing long-term research in the species' putative range was carried out, constructing a distributional map based only on specimens of proven origin and incontrovertible field sightings (Leite Pitman and Williams 2004). This map has been refined with subsequent sighting records (M.R.P. Leite Pitman pers. obs.). The northernmost record is in Mitú, Colombia, at 1º15'57"N, 70º13'19"W (Hershkovitz 1961), the southernmost in Bolivia at 14°25'47.9994"S, 63°13' 47.9994"W (R. Wallace pers. obs.), the easternmost record is from the vicinity of Fazenda Amanda, Viseu, Brazil, at 01º52'S, 46º44'W (Pereira 2002), and the westernmost in the Rio Santiago, Peru, at 4º37'S, 77º55'W (Museum of Vertebrate Biology, University of California, Berkeley, collected 1979).
A single specimen [MACN 31.59 held in the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”. (MACN). Colección de Mamíferos] collected on 4 June 1930 is documented as coming from western Pichincha in Ecuador (O.B. Vaccaro pers. comm.). A detailed locality is not provided and it is likely that it is mislabelled; the same collector collected another specimen on 30 July 1930 east of the Andes in Ecuador (specimen also in MACN). However, if the locality is correct, this would be the only record of the species west of the Andes and would mean that the species also previously occurred in the Chocó.
A specimen in the Santa Cruz Natural History Museum labelled as Atelocynus microtis, was genetically analysed and found to be a specimen of Cerdocyon thous (L. Emmons, pers. comm. 2008) which highlights the potential for misidentification between the two species in areas of savannah-forest ecotone in southern Amazonia (where the two species coexist).
Atelocynus microtis is a mid-sized canid with a large, fox-like head, short ears that are rounded at the tips, relatively short legs, and a long, bushy tail. Small-eared dogs have thick, sleek, dark pelage that may be in shades of brown, black, or gray and gradually fades into a dull reddish-brown on the underside. Markings include a narrow black collar, a dark band that extends along the top of the back and tail, and a patch of light-colored hairs around the pubic region and underside of the base of the tail. Individuals may exhibit different color patterns, but it remains unclear if these variations reflect age, distribution, molt, or other factors. Possibly because of their propensity to use water sources, small-eared dogs have a partial interdigital membrane. A pair of captive individuals were also described as having a notably visible tapetum lucidum, which caused the eyes to reflect brightly in conditions of low light. Compared to related species of South American foxes, small-eared dogs are fairly large. They have relatively short limbs and small ears compared to similar species and females are slightly larger than males.
Average mass: 9-10 kg.
Range length: 72 to 100 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
Average mass: 9500 g.
Atelocynus microtis prefers undisturbed lowland rainforests in the Amazon region. Within these lowland forests, there are records of A. microtis occupying terra firme forest, swamp forest, stands of bamboo and areas of primary succession along rivers, and there have been several reports of small-eared dogs swimming in rivers along with a prevalence of tracks along riverbanks and creeks. Whether or not they are able to use other habitats is still unknown, but there has been one sighting of an individual in a lowland forest that bordered savanna. There are very few records of A. microtis in areas with significant human activity or impact.
Range elevation: 0 to 1,000 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest
Other Habitat Features: riparian
Habitat and Ecology
The Short-eared Dog favours undisturbed rainforest in the Amazonian lowlands. The species has been recorded in a wide variety of lowland habitats, including terra firme forest, swamp forest, stands of bamboo, and primary succession along rivers. At Cocha Cashu, sightings and tracks of the species are strongly associated with rivers and creeks, and there are five reliable reports of Short-eared Dogs swimming in rivers. Records are very rare in areas with significant human disturbance, i.e., near towns or in agricultural areas. It is unclear whether the Short-eared Dog is able to utilize habitats outside wet lowland forests. One sighting in Rondonia, Brazil, was in lowland forest bordering savanna (M. Messias pers. comm.). The species has also been recorded up to 2,000 m elevation in montane forest on ridges adjacent to lowlands.
In an ongoing field study initiated in Madre de Dios, Peru in 2000, a female tracked for one year used an area of 8 km² and a dispersing male 30km² in 3 months. Preliminary evidence suggests that male territories probably do not overlap (M.R.P. Leite Pitman pers. obs.).
An ongoing study at the Cocha Cashu Biological Station using scat samples to better understand the diet of A. microtis has provided a significant amount of information. Small-eared dogs are generalist carnivores, but also appear to eat some fruits as well. The most prevalent item in their diet appears to be fish, which has been supported by the findings of Defler and Santacruz, who discovered the parasite Diphyllobothrium latum, which requires fish as an intermediary host, in the intestine of a museum specimen. Scat samples also contained insects and the remains of mammals such as agoutis, marsupials, and small rodents. About 10% of the samples contained the remains of fruits such as Borismenia japurensis, Strychnos asperula, Unonopsis floribunda, Pouteria procera, Sciadotenia precatoria, Trattinnickia species, and various Cucurbitaceae and Maraceae. In a couple of scat samples, Euterpe precatoria fruit was germinating. While they do not appear to be a major component of the small-eared dog’s diet, remnants of frogs, crabs, reptiles, and vegetable fiber were also found in some samples. There have also been some reports of A. microtis eating fallen Brosimum fruits and bananas as well as killing and eating poultry. Captive individuals in Bogota, Colombia were fed raw meat, kikuyu grass shoots, and foods that humans would typically eat.
Animal Foods: birds; mammals; amphibians; reptiles; fish; insects; aquatic crustaceans
Plant Foods: leaves; fruit
Primary Diet: carnivore (Piscivore ); omnivore
Little information is known about the general ecology of A. microtis as it is such an elusive species. Because A. microtis has a sleek, thick coat, it is suggested that it inhabits areas near water or with heavy rainfall and its short limbs allow for it to move about easily within dense forests. Small-eared dogs are generalist carnivores, preying on fish, insects, small mammals, amphibians, birds, and reptiles. They are also thought to be seed dispersers, as germinating fruit seeds have been found in their scat. They may be prey to ocelots, jaguars, and pumas. Small-eared dogs are hosts to various viruses. Common canine distemper virus and canine parvovirus affect this species and are transmitted through domestic and feral dogs. They are hosts to the cestode Diphyllobothrium latum, which requires a fish intermediate host.
Ecosystem Impact: disperses seeds
- cestodes (Diphyllobothrium latum)
There are no unequivocal data on what animals (if any) prey on A. microtis, but the presence of ocelot tracks around the remains of a juvenile in Cocha Cashu suggest that it may be a predator. Jaguars and pumas may also be predators due to their size and presence in the same habitats as A. microtis.
- ocelots (Leopardus pardalis)
- jaguars (Panthera onca)
- pumas (Puma concolor)
Anti-predator Adaptations: cryptic
Life History and Behavior
There is very little data on communication in small-eared dogs. Given their strong odor, the anal gland secretions are likely used as a device for communication. Also, the displays of aggression such as bared teeth and growling are almost certainly used as a warning to ward off potential threats.
Communication Channels: visual ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Nothing is known of the expected lifespan of A. microtis in the wild. In captivity, most short-eared dogs do not survive a full year. However, two captive animals have lived for 9 and 11 years, respectively.
Status: captivity: 11 (high) years.
Status: captivity: 11.0 years.
Lifespan, longevity, and ageing
Little information is known about the mating system of A. microtis and no information has been published on this topic. Females have been found with pups on rare occasions but no information is available regarding how mates are attracted or how their mating system works.
General reproductive behavior has not been formally studied in A. microtis, so little is known. Based on the finding of a juvenile carcass, it is believed that small-eared dogs give birth in May or June. Pups have also been found in the months of April, September, November, and December, suggesting that parturition occurs during the dry season. However, when breeding occurs and the length of gestation is unknown. Adults have been found with 2 or 3 pups in dens in hollow logs or paca burrows. Information on weaning or when pups reach sexual maturity is not known.
Breeding interval: Breeding interval is unknown.
Breeding season: Breeding season is unknown but breeding is thought to be seasonal.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Because studies of parental investment have not been formally conducted in A. microtis, little is known about the extent of the investment made at various stages of development. However, like all mammals, females invest substantially in gestation and lactation and young have been observed with females, suggesting some period of dependency.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)
With a population estimated at only 15,000 individuals, short-eared dogs are one of the rarest species of carnivores in South America. They are listed as near threatened according to IUCN’s Red List of Threatened Species. The major threats to this species are habitat loss and transmission of diseases from domestic dogs. These diseases include canine distemper virus and canine parvovirus. There are few reports of short-eared dogs being hunted for meat and no reports of hunting for fur. Short-eared dogs are not listed on any CITES appendix, but they are listed as an endangered species and protected by law in Brazil, and are currently on a preliminary list of endangered species in Colombia. In Peru, the species was recently taken off the list of protected species. Although there are efforts to protect short-eared dogs in some South American countries, no conservation efforts have been made to increase population numbers. Furthermore, at present no known short-eared dogs are being held in captivity, although there have been individuals held in zoos in the past. There is ongoing research being conducted on short-eared dogs in Peru. Efforts are being made to provide vaccinations for domestic dogs in the range of short-eared dogs in order to prevent disease transmission and there are efforts in place to expand studies of their ecology and conservation outside of Peru.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: near threatened
IUCN Red List Assessment
Red List Category
Red List Criteria
Although widespread, this species is rare and sightings are uncommon across its range. Although there are indications that the population may be recovering in some areas, with increasing numbers of sightings in recent years, this also reflects a greater number of biologists and tourists in the region and improvements in detection technology such as the use of camera-traps. Given the growing threats of habitat loss (especially due to large-scale conversion currently underway in Amazonia, especially for soybean production), prey-base depletion, and disease transmission from domestic dogs, it is inferred that the species has declined in the region of 20–25% over the past 12 years (estimated generation length = 4 years). The species is therefore listed as Near Threatened, based on approximating listing as Vulnerable under criterion A2.
- 2013Near Threatened
- 2008Near Threatened(IUCN 2011.1)
- 2004Data Deficient
- 1996Data Deficient
- 1994Insufficiently Known(Groombridge 1994)
- 1990Insufficiently Known(IUCN 1990)
- 1986Insufficiently Known(IUCN Conservation Monitoring Centre 1986)
- 1982Insufficiently Known(Thornback and Jenkins 1982)
The Short-eared Dog is notoriously rare, and sightings are uncommon across its range. However, this may not always have been the case. The first biologists to study the species found it relatively easy to trap during mammal surveys around Balta, Amazonian Peru, in 1969 (A.L. Gardner and J.L. Patton pers. comm.). Grimwood (1969) reported collecting specimens around the same time in Peru's Manu basin (now Manu National Park), suggesting that the species was also relatively common in that area.
Following these reports, the species went practically unrecorded in the Peruvian Amazon until 1987, despite intensive, long-term field surveys of mammals in the intervening years (Terborgh et al. 1984; Janson and Emmons 1990; Woodman et al. 1991; Pacheco et al. 1993, 1995). Even Louise Emmons, who carried out long-term monitoring and trapping of Ocelots (Leopardus pardalis) and other mammals at the Cocha Cashu Biological Station in Manu, never saw or trapped the Short-eared Dog (L. Emmons pers. comm. 2008). For whatever reason, the species appears to have gone entirely unrecorded from the region between 1970 and 1987.
This local and temporary disappearance is potentially related to transmission of diseases by domestic dogs, commonly brought by local indigenous into protected areas. Two disease surveys carried out in Manu National Park found parvovirus and distemper to be common among domestic dogs, posing a threat to Short-eared Dog populations and other carnivores inside Manu and Alto Purus National Park (Schenck et al. 1997; Leite Pitman, Nieto et al. 2003).
Over the last two decades, it appears that the species population may be recovering in some areas, with increasing numbers of sightings in recent years, but which also certainly reflects a greater number of biologists and tourists in the region and improvements in detection technology such as the use of camera-traps. Between 1987 and 1999, biologists working in the Peruvian department of Madre de Dios, mostly in the vicinity of Cocha Cashu Biological Station, reported 15 Short-eared Dog sightings. Surveys in Cocha Cashu conducted from 2000–2003 resulted in a few brief encounters, while surveys around the Curanja and Purus rivers found tracks in every creek visited (M.R.P. Leite Pitman pers. obs.). From 2003 to date, more than 100 camera-trap pictures of this species have been recorded at Los Amigos Biological Station, also in south-eastern Peru (M.R.P. Leite Pitman pers. obs.). The species has also been recorded by camera traps in northern Peru, Colombia, Ecuador, Bolivia and western and eastern Brazil.
The major threats to this species are habitat loss (especially due to large-scale conversion currently underway in Amazonia), prey-base depletion from hunting, and diseases. There are no reports of widespread persecution of the species.
Although protected on paper in most range countries, this has not yet been backed up by specific conservation action, although the species’ presence was a major factor for conservation efforts at Jamari National Forest, western Brazil (Koester et al. 2008).
The Short-eared Dog is likely to occur in most protected areas that encompass large tracts of undisturbed forest in western Amazonia. During the last decade, its presence has been confirmed in protected areas in Bolivia, Brazil, Ecuador and Peru.
The species is not included in the CITES Appendices.
No animals currently are known to be in formal captive breeding programmes. In the past, individuals have been held in several U.S. zoos (including the Lincoln Park Zoo, the National Zoo, the Brookfield Zoo, the Oklahoma City Zoo, and the San Antonio Zoo), mostly during the 1960s and 1970s (Leite Pitman and Williams 2004).
The biology, pathology, and ecology of the species are little known. Especially lacking is any true estimate of population density and an understanding of the species' habitat requirements. New GPS tracking technology will facilitate studies on density, habitat use and home-range.
Relevance to Humans and Ecosystems
Atelocynus microtis has no negative economic impact on humans directly, although it can carry the diseases canine distemper virus and canine parvovirus, both of which can occur in domestic and feral dogs. It is probably commoner, however, for domestic and feral dogs to transmit diseases to the short-eared dog.
Negative Impacts: causes or carries domestic animal disease
Because small-eared dogs are so elusive, there have been only a few reports of them having positive economic importance for humans. Short-eared dogs are occasionally hunted for meat, although not for fur. They have been captured in some cases for pets and for sale to local people and zoos. These instances, however, are rare.
Positive Impacts: pet trade ; food
The short-eared dog (Atelocynus microtis), also known as the short-eared zorro , is a unique and elusive canid species endemic to the Amazonian basin. This is the only species assigned to the genus Atelocynus.
It has many names in the indigenous languages where it is endemic, such as: cachorro-do-mato-de-orelha-curta in Portuguese, zorro de oreja corta in Spanish, nomensarixi in the Chiquitano language, and uálaca in Yucuna. Other names in Spanish are zorro ojizarco, zorro sabanero, zorro negro.
Evolution and systematics
After the formation of the Isthmus of Panama in the latter part the Tertiary (about 2.5 million years ago in the Pliocene), dogs migrated from North America to the southern continent as part of the Great American Interchange. The short-eared dog's ancestors adapted to life in tropical rainforests, developing the requisite morphological and anatomical features. Apart from its superficial resemblance to the bush dog, the short-eared dog seems not to be closely related to any fox-like or wolf-like canid.  It is one of the most unusual canids.
Two subspecies of this canid are recognized:
- A. m. microtis
- A. m. sclateri
Occurrence and environment
The short-eared dog can be found in the Amazon rainforest region of South America (in Peru, Bolivia, Brazil, Colombia, Ecuador and possibly Venezuela). It lives in various parts of the rainforest environment, preferring areas with little human disturbance. It lives in both lowland forests known as Selva Amazónica and terra firme forest, as well as in swamp forest, stands of bamboo, and cloud forest.
The short-eared dog has short and slender limbs with short and rounded ears. The short-eared dog has a distinctive fox-like muzzle and bushy tail. It ranges from dark to reddish-grey, but can also be nearly navy blue, coffee brown, dark grey or chestnut-grey until to black, and the coat is short, with thick and bristly fur. Its paws are partly webbed, owing to its partly aquatic habitat.
It moves with feline lightness unparalleled among the other canids. It has a somewhat narrow chest, with dark color variation on thorax merging to brighter, more reddish tones on the abdominal side of the body.
This wild dog is mainly a carnivore, with fish, insects, and small mammals making up the majority of its diet. An investigation led in Cocha Cashu Biological Station in Peru into the proportions of different kinds of food in this animal's diet produced the following results: fish 28%, insects 17%, small mammals 13%, various fruits 10%, birds 10%, crabs 10%, frogs 4%, reptiles 3%.
Reproduction and behavior
This species has some unique behaviors not typical to other canids. Females of this species are about one-third larger than males. The excited male sprays a musk produced by the tail glands. It prefers a solitary lifestyle, in forest areas. It avoids humans in the natural environment. Agitated males will raise the hairs on their backs.
Threats, survival and ecological concerns
Feral dogs pose a prominent threat to the population of short-eared dogs, as they facilitate the spread of diseases such as canine distemper and rabies to the wild population. Humans also contribute to the extermination of the short-eared dog by degradation of the species' natural habitat and the destruction of tropical rainforests.
Status of conservation
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