Animal Diversity Web

Geographic Range

Long-nosed montane ground squirrels, Hyosciurus heinrichi, are named from a specimen observed in Indonesia on the greater Sunda island of Sulawesi. It was found upslope on mount Latimodjong of Southern Sulawesi. Since, H. heinrichi have not been observed any further away than Ile Ile mountain in Northern Sulawesi. Their geographic range comprises the montane forest ecoregion of the Central Sulawesi western mountain chain, which covers 75,980 square kilometers. (Archbold and Tate, 1935; Musser, et al., 2010; Olson, 2023)

• Biogeographic Regions
• oriental
  • native

Habitat

Hyosciurus heinrichi live in wet, mossy montane forests. While they have been observed in subtropical or tropical rainforests and dry lowland grasslands of the Western mountain chain in Central Sulawesi, they are predominantly found beside streams and on hillsides or ridgetops in cool and damp highland montane forests. That is, they are rarely observed in lowland habitat. Suitable Sulawesi montane forest zones for H. heinrichi range from 1,000 meters to 2,400 meters in elevation, but they are much more common in upper montane forests above 1,4000 meters. (Archbold and Tate, 1935; Culmsee, et al., 2011; Musser, et al., 2010)

• Habitat Regions
• tropical

• Terrestrial Biomes
• rainforest

• Range elevation

  1,000 to 2.400 m

  to 7.87 ft

Physical Description

Hyosciurus Heinrichi are smaller ground squirrels – adults range in weight from 228 to 370 g – made recognizable by their characteristically long nasal region and short, round ears. Their tails are also short, making up 45% to 47% of their head and body length. Adult H. Heinrichi tail lengths range from 65 to 120 mm. Adult H. Heinrichi head and body lengths range from 195 to 240 mm. Hyosciurus heinrichi have long, slender hind feet sporting especially long, curving claws. Their claws are 25% to 35% of the length of their front feet. More immediately noticeable, H. heinrichi are dorsally dark with tawny speckles and are ventrally dark with a mid-ventral, irregular pure-white band from their mouth to their bellies. They have soft, thick fur to a length of around 35 mm all around the body. Their hands and feet backs are darker than the rest of the body. Hyosciurus heinrichi are monomorphic. The H. heinrichi dental formula is 1/1, 0/0, 1/1, 3/3. (Archbold and Tate, 1935; Musser, et al., 2010)

Adult H. heinrichi specimens can be differentiated from superficially similar Rhinosciurus: Adult Hyosciurus heinrichi nasal lengths are much longer than those for Rhinosciurus. Adult H. heinrichi specimens can also be differentiated from their close relatives, Hyosciurus ileile. Hyosciurus heinrichi have nasals about as long as their frontals, while H. ileile nasals are only 83% to 86% the length of their frontals. Also, H. heinrichi have a lighter body with shorter hind feet, longer claws relative to the size of their feet, and much smaller ectotympanic bullae than H. ileile. Young and old H. heinrichi specimens can be differentiated from each other: the nasal lengths of old H. heinrichi specimens are much longer than the nasal lengths of young specimens. (Archbold and Tate, 1935; Musser, et al., 2010)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike

• Range mass

  228 to 370 g

  8.04 to 13.04 oz

• Range length

  195 to 240 mm

  7.68 to 9.45 in

Reproduction

There is no information regarding Hyosciurus heinrichi mating systems. Instead, information can be extrapolated from a similar species. Callosciurus erythraeus are promiscuous. They exhibit a female defense mating system. Males compete for mates, then guard them for a short time. During this time, a male competitor can challenge, reproducing with the female if successful. (Hayssen, 2008; Musser, et al., 2010; Thorington, et al., 2012)

• Mating System
• polygynandrous (promiscuous)

Hyosciurus heinrichi may have up to one litter per year, and their litter size is 1-2 young per litter. There is no more data regarding H. heinrichi reproductive behavior. However, tropical ground squirrels such as H. heinrichi are generally sexually active year-round, with a period of highest sexual activity. For a comparable species Spermophilus citellus, this breeding period is in the spring. Their gestation lasts for about 1 month. Then, they give birth to altricial young that are kept protected in burrows and fed via lactation for 6 weeks. This is typical of ground squirrels. Juveniles reach maturity by the next breeding season, when they are slightly less than 1 year old. (Britannica, 2016; "European Ground Squirrel", 2023; Hayssen, 2008; Musser, et al., 2010; Thorington, et al., 2012)

• Key Reproductive Features
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual

• Breeding interval

  Long-nosed montane ground squirrels breed once yearly

• Breeding season

  Unknown

• Range number of offspring

  1 to 2

• Average gestation period

  4 weeks

• Average weaning age

  6 weeks

• Average time to independence

  1 years

• Average age at sexual or reproductive maturity (female)

  1 years

• Average age at sexual or reproductive maturity (male)

  1 years

Hyosciurus heinrichi are known to burrow, though burrow size is not established. Hyosciurus heinrichi mothers leave their young either underground or in nests made in logs. There is no more specific, relevant data to make any more claims about H. heinrichi parental care. However, ground squirrels do not need to spend as much effort attending to altricial young as arboreal squirrels do. Information about Urocitellus parryii will now be extrapolated to H. heinrichi: Adult males defend territory, acting as lookouts – and making calls – especially while females are lactating. (Hayssen, 2008; McLean, 1983; Musser, et al., 2010)

• Parental Investment
• altricial
• female parental care
• pre-weaning/fledging
  • protecting
    • male

Lifespan/Longevity

There is no published data regarding Hyosciurus heinrichi lifespan. However, another ground squirrel of similar size, the Spermophilus citellus, lives 6 to 7 years on average in captivity (up to 10 years maximum) but only 2 to 3 years in the wild, on average. Odds of predation, disease, accident, etc. accumulate over the years. So, animals in the wild do not live to the ages seen in captivity. (Weigl, 2005)

• Average lifespan
  Status: captivity

  10 years

• Typical lifespan
  Status: wild

  2 to 3 years

• Typical lifespan
  Status: captivity

  6 to 7 years

Behavior

Hyosciurus heinrichi are rarely observed due to extensive understory ground cover making it nearly impossible to sight them. Hyosciurus heinrichi are semi-fossorial and terrestrial and they are diurnal. They have been observed foraging through low moss on tree trunks, too. They usually root through the forest floor for food and communicate with others of their species. Hyosciurus heinrichi may dig burrows underneath or make nests inside of downed logs. There is no evidence of H. heinrichi hibernation nor is there any information on H. heinrichi group size. They are observed as solitary. (Musser, et al., 2010)

Hyosciurus heinrichi silently sit back on their haunches, occasionally twitching their tail, to observe their surroundings. When comfortable, they groom, scratch, and bite at parasitic infestations, and chirp or sniff around. When H. heinrichi call, they stretch their tail out behind their body; otherwise, H. heinrichi keep their short tails pressed to their backs when they are not moving. (Musser, et al., 2010)

• Key Behaviors
• fossorial
• diurnal
• motile

Communication and Perception

Hyosciurus heinrichi have a specialized sense of smell. They also have sight and hearing to perceive. To communicate, H. heinrichi emit series of single chirps. They chirp more rapidly when they are distressed. When agitated, they chatter like most other squirrels do. Most of the time, though, their calls are almost undistinguishable from bird calls, likely an adaptation to avoid being noticed or singled out by nearby predators. All H. heinrichi calls are light in timbre. (Musser, et al., 2010)

• Communication Channels
• acoustic

• Other Communication Modes
• mimicry

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Hyosciurus heinrichi are insectivorous and frugivorous. Alongside fruit, they eat beetles, pomarine and formicine ants, dipteran and beetle larvae, centipedes, and cockroaches foraged from leaf litter using their elongated muzzle and long claws. They poke through litter and moss to find prey, then dig and pounce on unsuspecting invertebrates. Hyosciurus heinrichi likely utilize a highly developed olfactory acuity to locate and identify their prey. When they are not hunting for arthropods, H. heinrichi are seen using their sturdy incisors and strong jaws to muscle open and mash acorns into a digestible paste. (Musser, et al., 2010)

• Primary Diet
• carnivore
  • insectivore
• herbivore
  • frugivore

• Animal Foods
• insects

• Plant Foods
• fruit

Predation

Hyosciurus heinrichi vocalizations mimic bird calls, likely to avoid predation. Also, they are dark, likely to avoid detection by overhead arboreal and avian predators. The following predators’ geographic ranges overlap with that of H. heinrichi and likely will prey on long-nosed montane ground squirrels: the endemic 'Sulawesi palm civets Macrogalidia musschenbroekii'; the introduced 'common palm civets Paradoxurus hermaphroditus' and 'Malaysian civets Viverra tangalunga'; 'peregrine falcons Falco peregrinus', 'Indian black eagles Ictinaetus malaiensis', 'Sulawesi hawk-eagles Nisaetus lanceolatus'; various of the 52 identified Sulawesi snake species. Also, though unsubstantiated, it is thought that feral dogs and cats might also prey on H. heinrichi. Finally, the people of Sulawesi have an active bush meat trade. Though the species have not been identified, Sulawesi bush meat piles have squirrels, so it is possible that humans eat H. heinrichi, too. (Bailey, et al., 2022; Hunowu and Patandung, 2019; Musser, et al., 2010; Thiollay and Rahman, 2002; Vogel and Lang, 2006)

• Anti-predator Adaptations
• mimic

Ecosystem Roles

Hyosciurus heinrichi disperse oak seeds by casting away half eaten husks. They also act as ecosystem engineers, making burrows and/or nests for even smaller biota to potentially inhabit. Hyosciurus heinrichi place evolutionary pressure on invertebrates. Hyosciurus heinrichi act as hosts for the uniquely parasitizing sucking louse, Hoplopleura heinrichi. Hyosciurus heinrichi also act as hosts for ectoparasitic hard tick larvae and for nematodes. Lastly, H. heinrichi act as prey for nearby predators and as material for decomposers. (Musser, et al., 2010)

• Ecosystem Impact
• disperses seeds
• creates habitat

Economic Importance for Humans: Positive

Hyosciurus heinrichi eat many acorns when they are available. In doing so, they assist oak seed dispersal. Acorn-eating squirrels sometimes abandon half-eaten acorns, spreading viable oak seeds further than gravity or wind alone could carry them. They then positively economically important for the timber industry that relies on natural seed dispersal for forest regeneration. Hyosciurus heinrichi also likely play a positive economic role as bush meat: Humans make money by selling H. heinrichi as food. (Bailey, et al., 2022; Musser, et al., 2010)

• Positive Impacts
• food

Economic Importance for Humans: Negative

There are no known adverse effects of Hyosciurus heinrichi on humans.

Conservation Status

Hyosciurus heinrichi is an IUCN least concern species. Key Sulawesi montane ecoregion biodiversity hotspots have been identified for conservation. Still, H. heinrichi habitat is lost and degraded due to logging and agricultural expansion. There is no information on H. heinrichi population trends or changes in their distribution, but Sulawesi conservation is achieved such that H. heinrichi are not suspected to be facing population decline. (Olson, 2023)

• IUCN Red List

  Least Concern

Contributors

Brian Oler (author), University of Washington, Laura Prugh (editor), University of Washington, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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Bailey, C., H. Hilser, Y. Siwia, J. Waterman, T. Loffeld, H. Sampson, J. Tasirin, V. Melfi, A. Bowkett. 2022. Trends in the bushmeat market trade in North Sulawesi and conservation implications. Animal Conservation, 25/1: 4-14. Accessed June 06, 2023 at https://pure.hartpury.ac.uk/ws/portalfiles/portal/34057069/Trends_in_the_bushmeat_market_trade_in_North_Sulawesi_and_conservation_implications.pdf.

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Hunowu, I., A. Patandung. 2019. "

Sulawesi’s mysterious apex predator

McLean, I. 1983. Paternal behaviour and killing of young in Arctic ground squirrels. Animal Behavior, 31/1: 32-44. Accessed June 06, 2023 at https://www.sciencedirect.com/science/article/pii/S0003347283801717.

Musser, G., L. Durden, M. Holden, J. Light. 2010. 11 June 2010 Systematic Review of Endemic Sulawesi Squirrels (Rodentia, Sciuridae), with Descriptions of New Species of Associated Sucking Lice (Insecta, Anoplura), and Phylogenetic and Zoogeographic Assessments of Sciurid Lice. Bulletin of the American Museum of Natural History, 339: 1-260. Accessed June 06, 2023 at https://bioone.org/journals/bulletin-of-the-american-museum-of-natural-history/volume-2010/issue-339/695.1/Systematic-Review-of-Endemic-Sulawesi-Squirrels-Rodentia-Sciuridae-with-Descriptions/10.1206/695.1.full.

Olson, D. 2023. "Sulawesi Montane Rainforests" (On-line). One Earth. Accessed June 06, 2023 at https://www.oneearth.org/ecoregions/sulawesi-montane-rainforests/.

Thiollay, J., Z. Rahman. 2002. The raptor community of Central Sulawesi: habitat selection and conservation status. Biological Conservation, 107/1: 111-122. Accessed June 06, 2023 at https://www.sciencedirect.com/science/article/pii/S0006320702000514?casa_token=_onx6nqa3d8AAAAA:gwyItWnbEOFrf_3P3g0emlsHwEcYXRlKb_95nF-I5ioaGOzE4mNLHxdPKtAzOlX4t_OYdQBB-Wo.

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Vogel, G., R. Lang. 2006. The Snakes of Sulawesi. Herpetologia Bonnensis, II: 35-38. Accessed June 06, 2023 at https://www.yumpu.com/en/document/read/6805571/the-snakes-of-sulawesi-seh.

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