Tibetan antelope rests like a Puppet

Rest contributes to a large part of animals’ daily life, and animals usually rest in two ways, standing or in recumbence. For small or medium sized ungulates, they bed to rest in most cases, and standing rest is very rare and hardly seen. Here we described a standing rest behaviour of medium sized Tibetan antelopes (Pantholops hodgsonii) living on the roof of the world, Tibet Plateau, which has not been reported before. We named the standing rest behaviour here as Puppet behaviour, since the antelope can stand still for a certain time just like a Puppet. Of the total 304 focal individuals, 48.3% (98/203) of adult and sub-adult males expressed the Puppet behaviour, whereas only 6.3% (6/96) of females did, indicating an obvious sexual difference. Puppet behaviour occurred more frequently at noon and in the afternoon on sunny and cloudy days, meaning that day time and weather were both influential factors. Puppet behaviour was usually accompanied with rumination and sometimes ended with leg-shaking. Our results suggest that Puppet behaviour is probably an adaptive form of rest, which serves a thermoregulatory and anti-predation function, and is much simpler and safer than recumbent rest.

medium sized ungulates including Tibetan gazelle (P. picticaudata) [11], Asiatic 48 ibex (Capra sibirica) [12,13], and goitred gazelle [14]. However, standing rest 49 seems common in large body-sized ungulates, just like Asiatic wild ass (Equus 50 hemionus), they spend nearly one third to rest [14]. Similarly, elephants have an 51 average daily total sleep (standing or in recumbence) time of 2 h due to the large 52 body size, and only exhibit recumbent sleep every third or fourth day [15][16][17]. 53 We started our field behavioural study on medium sized Tibetan antelopes in 54 2016, and found that Tibetan antelopes especially males sometimes kept standing for 55 several min (see supplemental video 1 and Fig 1). During this time, they didn't feed, 56 didn't move, and just kept their body motionless, like a puppet. In small or medium 57 sized ungulates, standing usually severs as anti-predation vigilance [11,18], but this 58 standing-still behaviour or called Puppet behaviour seemed very different from 59 vigilance, since their head also kept motionless and was usually under shoulder, and 60 thus probably cannot detect a whole of their surroundings. 61 To our knowledge, there is not any report on this kind of standing behaviour in 62 Tibetan antelopes, or other median or small sized ungulates. We considered that the 63 Puppet behaviour serves a primary function of rest, thus we can predict that this 64 behaviour would occur less frequently in early morning, since they need more time to 65 feed after a whole night rest. Puppet behaviour might also serve a thermoregulatory 66 function, because when they stand still, they have a much larger body surface contact 67 with the air, and therefore we predict that the Puppet behaviour would occur more 68 frequently on sunny or cloudy days than on rainy or overcast days. Puppet behaviour 69 means motionless, and can be considered as a vulnerable time for the antelopes but a 70 great time for predators. As a sexually segregated species, males of Tibetan antelope 71 are much larger and stronger, and thus more tolerant than females when confronting 72 with predators. From a view of anti-predation, we can predict that Puppet behaviour 73 would occur more frequently in males than in females. Here we collected two years 74 data to explore if the occurrence of Puppet behaviour is related to the day time, 75 weather and sex-age.    Observations were carried out from the roadside using binoculars (8X42) or a 111 telescope (20~60X63). We walked or drove regular routes to find targets for video 112 recording.

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For most groups, we focal sampled one or two individuals. We may collect a few 114 more samples for some large female groups (usually more than a few hundred 115 individuals), but we will collect from different part of the group to avoid resampling.

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It was not practically feasible to mark individuals or to recognize individuals through 117 particular features, and thus there was a possibility that a focal individual was 118 recorded more than once. However, since the population was more than 10 000 and 119 extremely large, the possibility of resampling in a same day was rather small.

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At the beginning of each focal observation, we recorded the date, time of day, 121 location, weather, group type, and group size. Since the antelopes are sexually 122 segregated, only three group types (single-male groups, single-female groups and 123 mother-lamb groups) could be found during summer. Focal individuals were 124 classified into four categories: adult male, sub-adult male, female and lamb. It was not 125 practically feasible to distinguish adult females from sub-adult females, and thus the 126 two age classes were therefore collapsed.

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The Puppet behaviour was expressed 344 times in 104 of the total 304 samples.

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Hereafter we described the behaviour with respect to each environmental and social 148 factor.

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Puppet behaviour was defined as standing still, without any acts of their whole 150 body for a certain time (ranged from 2 to 842 s, with a median of 57 s). We measured 151 the angle between their neck and foreleg, and found that the angle was usually 152 between 40° and 100° (Fig 1 & 2). Comparably, when the antelopes were feeding, the 153 angle was usually less than 40°; and when they were in vigilance, the angle was  With the help of the logistic model, we found that the occurrence of Puppet 159 behaviour was affected by day time (Wald=8.114, df=2, P=0.017, fig 3), weather 160 (Wald=22.121, df=2, P<0.001, fig 4)    Both day time and weather can influence Puppet behaviour, but they were not the 228 determinants since the behaviour also occurred in the early morning and on rainy or 229 overcast days. It is easy to understand that the antelopes expressed a lower Puppet 230 behaviour in the early morning since they have spent a whole night sleep and need 231 more time to feed. The rest starts after they fulfill their stomachs at noon and occurs 232 frequently in the afternoon. The Puppet behaviour occurs more frequently when the 233 weather is sunny or cloudy, and probably it serves a function of thermoregulation.

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The elevation in this area is very high and the average temperature is relative low 235 compared with other areas [25]. However, the sun radiation is rather strong and the