Statistical analyses

Body weight measurements between sexes of the same species were compared by Students T test, to determine if there was sexual dimorphism.

4.5 Results

4.5.1 Species trapped

Over 5040 trap-nights 177 rodents were trapped and processed. Seven species and species from one genus of rodent were identified by NGS, either from tissue samples or faecal samples. These were Spermophilus erythrogenys- red cheeked ground squirrel, Allactaga sibirica –Siberian jerboa, Meriones meridianus- midday gerbil,

Cricetulus longicaudatus- long-tailed dwarf hamster, Cricetulus migratorius- grey

dwarf hamster, Cricetulus kamensis – Kam dwarf hamster, Ochotona pallasi -pika and Alticola spp. – Voles could not be identified further than genus. Three specimens

could not be identified, as they did not match any known descriptions either morphologically or by DNA. (See Plate 4.3)

Plate 4.3 Unidentifed rodent species.

The rodent species pictured in plate 4.3 was captured three times and remains unidentified – it did not match any description in the guidebook or DNA identification. It was significantly bigger than the other hamster/vole species, furrier and had a reddish/tan tinge to the fur tip.

4.5.2 Habitat

The red-cheeked ground squirrels were captured in the open steppe areas with little rock cover and also on the low hillsides with their burrows dug on an angle into the ground. There was generally a pile of dirt around the entrance to the burrow from the excavating. The jerboas were captured in the open flat steppe areas but in areas with harder, rockier soil and occasional small bushes. The jerboas’ burrows appeared to

unaffected. We reset traps once the water had subsided and animals were caught the next day,

Gerbils were captured along small sandy gullies, with their burrows dug in the root system of Amygdalus pedunculata. There were often caches of nuts from the bushes around the entrance to the burrows (Plate 4.6). The pikas were captured in rocky outcrops/boulder piles with a network burrow system with numerous entrances and exits. The entrances to the burrows were often marked by piles of faecal stacks and stores of nesting material (Plate 4.7). An exception was a solitary pika trapped in 2015, with a burrow under a red bush, distant from any colony. Hamsters and voles were trapped in the steep rocky gullies and recaptures were common (Plate 4.9). Most species appeared to be nocturnal or crepuscular, no traps were set off during the day although young ground squirrels were observed playing during the day.

Plate 4.5 Jerboa habitat.

Plate 4.9 Hamster and vole habitat.

4.5.3 Physical assessment

Many of the females of all species were pregnant or lactating (26%) at the time of capture. Approximately equal numbers of both sexes for each species were trapped, except for the ground squirrels where no adult males were trapped. Only one juvenile male ground squirrel was caught late in the season. In 2015 we trapped earlier

(March to April) to determine if males came out early for mating but no ground squirrels were seen of either sex.

Sexual dimorphism was observed between the male and female long- tailed dwarf hamsters when their body weights were compared by students T-Test (P=0.05, t= 3.9). There was no statistically significant sexual dimorphism between the remaining rodent species when weights were compared. Jerboas P= 0.05, t=0.21, gerbils P=0.05, t= 1.97. With the remaining species-: red–cheeked ground squirrels, grey hamsters, Kam dwarf hamsters, pikas and the voles, the numbers were too small to get significant results with the T-test.

Plate 4.10 Variation in tail tip colouration in gerbils.

Table 4.1 Mean +/- Standard Deviation and range of physical measurements of rodents captured in the Tost Mountains of Mongolia between 2012 and 2015.

Species Weight

g mm HL mm HW CR m mm TL mm FL mm LL mm EL| Ground Squirrel Spermophilus

erythrogenys N=19 27029 230-330 48.93.7 44-58.5 29.53.3 22-33 16615 135-188 535.3 44-60 36 34-39 43 36-48 Jerboa Allactaga sibirica N=16 926.8 85-100 382.4 34-42 232.9 20-29 1168.6 105-130 18114 145-200 642.7 58-68 585 42-62 325 25-35 Gerbil Meriones meridianus

N=23 588. 50-70 382.7 34-41 202.1 17-21 70-116 9911.4 9914 70-116 292.1 26-31 352.9 33-40 1222 9-16 Long-tailed Dwarf Hamster

Cricetulus longicaudatus N=67 22.65 15-30 27.32.9 23-31 13.81.9 12-15 76.813.6 55-110 305 21-39 161.5 11-18 23.73.6 16-30 131.7 11-16 Vole Alticola sp. N=5 445.5 40-50 32.83.6 25-33 16.81.8 15-19 92-107 98.85.7 22.42.1 20-25 17.22.2 15-20 29.45.8 24-39 12.61.7 11-15 Kam Hamster Cricetulus kamensis N=5 284 20-30 274 20-30 152 12-18 718.4 58-81 22.63.7 19-27 152 12-17 222.6 19-26 12.40.8 11-13 N=number of animals sampled, HL-head length, HW- head width, CR-crown rump, TL-tail length, FL-Foot length, LL-leg length, EL- ear length.

4.6 Discussion

We trapped at least eight of the 24 species of rodents described for the Tost region (Batsaikhan 2010). Morphological characteristics that we observed in each rodent species differed from those characteristics reported by Batsaikhan (2010), Moreover, we found that pelage colour, tail tassels and presence of hair on hind feet pads we unreliable descriptors for identification as they varied between individuals within species. The only reliable source of species identification was by genetic analyses which illustrates the benefit of genetic approaches when studying rare and elusive species (Esson et al. 2017). Trapping, handling and sample collection appeared to have little impact on pregnant females as juveniles, especially ground squirrels, were observed in burrows where females had been trapped and handled.

Establishing information on the assembly of rodent species in mountain deserts is important, as rodents are significant prey species and carriers of disease (Singleton et al. 2003, Achazi et al. 2011). For example, Esson et al. (unpublished data, Chapter 3) identified rodents in this regions had been exposed to serious zoonotic pathogens such as Toxoplasma gondii (16.3%), Coxiella burnetii (16%), Puumala hantavirus (6%) and Leptospira interrogans (34%) serovars Australis and Icterohaemorrhagiae . These zoonoses pose a threat to sympatric wildlife, the local people and their

livestock. The fact that all species except for the ground squirrels and pikas were trapped inside gers means a potential health risk for the local people.

4.6.1 Species identification 4.6.1.1 Ground Squirrels

DNA analyses identified the ground squirrels we trapped as red-cheeked ground squirrels however their body measurements were consistent with descriptions of the Alashan ground squirrel- Spermophilus alashanicus, by Batsaikhan (2010). The red- cheeked ground squirrels in my study had body weights ranging from 230-330 g

in colouration than reported for the red-cheeked ground squirrel in (Batsaikhan 2010). Batsaikhan did not provide information on sex and age, sample sizes and capture location, all of which may have influenced differences in results between studies.

Unexpectedly, we did not trap any mature male ground squirrels. Female ground squirrels from other regions in Mongolia are reported to live with their young until the young disperse, while juveniles and males are solitary (Nyamsuren et al. 2014). Male arctic ground squirrels may disperse straight after mating in the burrows or disperse as soon as they emerge from hibernation (Karels and Boonstra 2000, Gillis 2002). The literature did not suggest male ground squirrels exhibit semelparity as some male dasyurids do (Boonstra, 2005), but they do undergo stress responses due to mating that may cause them to die post-mating (Boonstra 2001, Gillis 2002). It is possible the male ground squirrels in Mongolia die underground after mating or disperse. However, further work on their life history is needed. Juveniles were seen to emerge in late June.

4.6.1.2 Jerboas

The Siberian jerboa is one of 10 species of jerboa that are reported to occur in the Gobi Desert (Nyamsuren et al. 2014). Our measurements differed to Batsaikhan (2010), particularly in body length (105-125mm, vs 125 -180) weight (85-100g vs 85- 170g) and ear length (23-35mm vs 36-55mm). These small discrepancies could be due to variation between individuals within species, geographic variation, or different reference points for taking measurements. As sample sizes, sex and age were not given in (Batsaikhan 2010), the significance of the differences could not be

determined.

4.6.1.3 Gerbils

Gerbils were identified genetically as midday gerbils Meriones meridianus but

phenotypically had characteristics of both the midday gerbil and the Mongolian gerbil, which is also reported in the area (Batsaikhan 2010). Midday gerbils are not

described as having black hairs to the tail tips or a tassle, (Batsaikhan 2010),

hairy foot-pads. Our body measurements were similar to those previously described (Batsaikhan 2010).

4.6.1.4 Hamsters

Long-tailed dwarf hamsters, grey dwarf hamsters and the voles were all difficult to distinguish based on physical characteristics, although the voles on average were larger. There were large variations in coat colour, tail length and hair cover and presence of hair on foot-pads of the hamsters and voles. It is possible that there are hybrids among these species and further genetic sequencing could be used to determine relatedness. However, characteristic traits for the species were apparent with the long-tailed dwarf hamsters (nick-named “lion mice”) being very vocal and aggressive while being handled. Voles had very loose skin and could easily rotate while being held but were not as aggressive as the hamsters. In 2015 we trapped in a different area and found many of the long-tailed dwarf hamsters had definite bends or “kinks” in the distal third of their tails. It is possible that there are hybrids among those species – and similarly to above more work is needed on genetic sequencing to examine this possibility further.

The grey hamster is listed as data deficient and near threatened in the IUCN

Mongolian Red list of animals (Clark 2006); therefore, the information gained in this study will contribute t the knowledge of the biology of the grey hamster. We also trapped hamsters that looked like the desert hamster Phogopus roborovskii, but their DNA matched either the grey dwarf hamster or the long-tailed dwarf hamster.

Surprisingly we did not trap any Mus musculus (House mouse), which are reportedly ubiquitous over the whole of Mongolia (Nyamsuren et al. 2014).

Plate 4.12 Dwarf grey hamster.

Plate 4.13 Desert hamster.

A dwarf grey hamster that we trapped (Plate 4.12) compared with a photo of a desert hamster (Plate 4.13) from the guidebook (Nyamsuren et al. 2014). They have a similar appearance, but the grey dwarf hamster has furrier ears.

4.6.1.5 Cricetulus kamensis

Also known as the Kam hamster, Cricetulus kamensis has not been recorded in this area before, with the nearest report in China approximately 500kms away (Kang et al. 2016, Esson et al. 2017).

4.6.1.6 Pikas

We trapped one of two species of pikas listed for the region, Ochotona pallasi (Mongolian pika) by (Batsaikhan 2010). All pikas observed (except one), lived in family groups in boulder fields with numerous entrances and exits to their burrow system. We caught only four individual pikas, which differed greatly in physical

measurements to each other, likely due to differences in age of the animals captured. The pikas had four toes on the hind feet, which were covered in tan coloured fur, whereas Batsaikhan (2010) describes them with five toes and pads that are covered in grey hair.

4.6.2 Habitat

The habitats used by the different species were similar to habitats described for these species where they occurred in other regions (Gillis 2002, Liu et al. 2007, Nyamsuren et al. 2014). However, where we captured jerboas and gerbils, their burrows appeared to be in areas with less grass cover than previously described.