1 1 Ground Squirrels Marie Kubiak 1.1 ­Introduction are inquisitive and highly active so enclosures should be secure – such as large aviaries with narrow spaced mesh. Nest Ground squirrels make up the subfamily of Xerinae, within boxes should be provided (at least one per animal) with hay the Sciuridae (squirrel) family and include a variety of substrate and branches, tunnels, hides and wheels ­provided well-known species such as the groundhog and marmot. for enrichment and to encourage activity. Chipmunks will The species within this subfamily that are more commonly chew plastics, wood, wires and other ­materials and this should kept as pets, and are covered in this chapter, are prairie be taken into account when planning enclosure construction, dogs, Richardson’s ground squirrels and Siberian chip- and when toys or décor are added. They are omnivores and munks. Biological parameters for these species are included can be fed a rodent pellet diet but this should be supplemented in Table 1.1. with seeds, vegetables, insects, and hay. Food may be stored in substrate or nest boxes so it is important to check and clean enclosures thoroughly on at least a weekly basis to prevent 1.2 ­Husbandry spoilage. Fresh water should always be available and water bottles are generally accepted well. Free range access within a 1.2.1 Siberian Chipmunks house is not advisable due to potential for escape, injury, or damage inflicted to household possessions. In winter wild Siberian chipmunks (Tamias sibiricus) are squirrel-like chipmunks do not exhibit true hibernation but have fluctuat- rodents originating primarily from Northern Asia. Although ing torpor, with several days of dormancy followed by a period common in the pet trade in Europe in the late twentieth and of normothermia, activity, and feeding. In torpor their body early twenty-first century, in 2015 this species was added to temperature drops to around 5 °C and heart rate slows to EU Invasive Alien Species (IAS) Regulation (1143/2014), 4 beats/min. In captivity there is no drive for torpor as tem- resulting in a ban within the European Union on importation, peratures tend to remain stable through seasons and food is keeping, breeding, transport, trade, and accidental or inten- abundant. There is no evidence that absence of torpor has any tional release of this species, though an exemption is made for negative impact. animals to be transported for veterinary care. As such this ­species can only be kept by existingCOPYRIGHTED owners for their natural MATERIAL 1.2.2 Prairie Dogs lifespan, or under licence for medical, research, or­conservation purposes. At present these restrictions remain in place for the Prairie dogs (Cynomys spp.) are large, North American United Kingdom. Pet Siberian chipmunk numbers are declin- members of the squirrel family and have five recognised ing as animals reach the end of their life and no new animals species. Of these only the black-tailed prairie dog (Cynomys are able to be acquired or bred. Other species of chipmunks ludovicianus) is encountered with any frequency as a pet in may be legally kept but are extremely rare as pets. The Pallas the UK. Well-socialised individuals can make good pets but squirrel (Callosciurus erythraeus) and Fox squirrel (Sciurus even the tamest prairie dog can become aggressive during niger), both rarely kept as pets, have also been listed as­invasive their breeding season. species and are subject to the same restrictions. Captive animals require deep substrate to form their Chipmunks are terrestrial though have good climbing ­burrows as well as a large overground area for activity, ­capabilities and will use the full height of enclosures. They ­sufficient to enable a group of animals to be kept together. Handbook of Exotic Pet Medicine, First Edition. Edited by Marie Kubiak. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/kubiak/exotic_pet_medicine 0004775566.INDD 1 8/6/2020 3:27:02 PM 2 1 Ground Squirrels Table 1.1 Biological parameters (for animals not undergoing torpor). Body Respiratory rate Heart rate Sexual Body weight Lifespan temperature (°C) (/min) (/min) maturity Gestation Siberian Chipmunk 50–150 g 5–10 years 37–38 70–80 250–350 8–14 months 30–31 days (Tamias sibiricus) Black tailed-prairie dog 0.7–2 kg 7–10 years 35.3–39 40–60 200–318 2 yrs 30–35 days (Cynomys ludovicianus) Richardson’s Ground 0.4–0.6 kg 4 years 37.5–39.5 40–100 245–275 11 months 23 days Squirrel (Urocitellus richardsonii) Enclosure size requirements have been detailed as increase body condition but can lead to obesity or disruption 2 × 2 × 2.5 ft (L × W × H) per animal (Pilny and Hess 2004) to normal intestinal function if fed in excess. but this should be regarded as an absolute minimum and 4 × 4× 2.5 ft would be considered more suitable as a mini- 1.2.3 Ground Squirrels mum to allow animals to display normal behaviour. An area of deep substrate should be provided to allow creation Ground squirrel species are uncommon as companion ani- of burrows and can be hay, shredded paper, or soil. Artificial mals though Richardson’s Ground squirrels (Urocitellus rich- burrows and shelters such as drain pipes or wooden boxes ardsonii) (RGS) are occasionally kept. This species is native can be provided for hide and sleeping areas. Cage bars to the grasslands of the Northern United States of America should be no further than 1 inch apart to prevent escape. and Southern Canada and do cross over territory with prairie An elevated observation shelf should be provided as prairie dogs. In the wild, female familial groups exist with solitary dogs are inquisitive and will often climb to investigate males only being tolerated during breeding. In captivity they activity in the surrounding area (Pilny and Hess 2004). can be maintained in social single-sex colonies or mixed sex Plastic should be avoided as it is likely to be chewed. colonies with males being neutered. Though destructive and Chosen toilet areas will be well defined allowing easy daily with a tendency to bite defensively, RGS tend to make good cleaning of urine and faeces and a litter tray can be placed companion animals with regular handling and interaction. in the chosen site. A warm room or supplemental heating Captive animals have similar requirements to prairie is necessary to provide temperatures of 20–22 °C as prairie dogs, though as a smaller species enclosures can be less dogs may enter torpor at cooler temperatures (Johnson- extensive, with 3 × 2 × 1.5 ft advised per animal. Cage bars Delaney 2006). Torpor is not obligatory in prairie dogs but should be no more than 0.75 inch apart. The observation is a facultative response to temperature drop and lack of shelf should not be placed more than 18 inches above the available food and water. Although body temperatures ground as RGS are not good climbers. Ambient tempera- reduce, they remain significantly higher than ambient tures of 18–25 °C are advisable but they are adapted to cooler environmental temperature at approximately 19 °C even in temperatures and will not enter torpor unless temperatures deep torpor bouts. These deep torpor bouts are interspersed drop to below 7 °C (Michener 1983). In the wild RGS are with periods of activity and normothermia when environ- obligate hibernators and will spend up to nine months of mental conditions improve (Lehmer et al. 2001). As torpor the year in true torpor, with body temperature dropping to is facultative there is no need to replicate the conditions in close to environmental temperature as heart and respiratory captivity and to date no adverse effects have been reported rates slow dramatically (Michener and Koeppl 1985). Brief with absence of torpor in prairie dogs. periods of around 12 hours of warming to normal body tem- Prairie dogs are hindgut fermenters and require a high perature occur during this torpor (Michener and Koeppl fibre intake to maintain intestinal health. Where a normal 1985). In captivity temperatures are stable and food is read- appetite is present, provision of a variety of grasses, hay, flow- ily available and torpor rarely occurs. These less harsh con- ers, herbs, fresh vegetables and leaves and occasional inverte- ditions aid overall longevity but the lack of torpor and high brates is appropriate (Orcutt 2005). Pelleted diets designed for metabolic rate all year round may be associated with higher rabbits or rodents can be convenient food source for owners rates of neoplasia seen in RGS in captivity. but should make up no more than 10% of the diet, with high RGS are omnivorous with their dietary requirements fibre material making up the majority of food provided. Seeds intermediate between prairie dogs and chipmunks. Seeds and grains can be offered in small quantities as treats or to should be limited to occasional treats to avoid obesity. 0004775566.INDD 2 8/6/2020 3:27:02 PM 1.3 ­Clinica Evaluatio 3 1.3 ­Clinical Evaluation 1.3.1 History-Taking A full review of husbandry is essential as inappropriate conditions are common causes of health concerns. Contact with other animals, diet, previous medical history, enclo- sure size and set-up, and reproductive status are all key information. It is prudent to ascertain familiarity of indi- vidual animals with handling before attempting restraint. For individual health complaints, the duration of symp- toms, number of animals affected, and any changes made to environment in the period preceding clinical disease should be ascertained. 1.3.2 Handling Chipmunks are fast moving, adept at climbing and jump- ing, and rarely habituated to handling.