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 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 )

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.

• Terrestrial

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

Wetlands: swamp

Other Habitat Features: riparian

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

Commensal/Parasitic Species:

• 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.

Known Predators:

• ocelots (Leopardus pardalis)
• jaguars (Panthera onca)
• pumas (Puma concolor)

Anti-predator Adaptations: cryptic

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 ; acoustic

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.

Range lifespan

Status: captivity: 11 (high) years.

Average lifespan

Status: captivity: 11.0 years.

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); 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

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