Influence of ambient temperature on diurnal activity of Arabian oryx: Implications for reintroduction site selection

Abstract

The distribution of the Arabian oryx Oryx leucoryx had declined markedly by the time European explorers documented distributions, and the species became extinct in the wild by the mid 1970s. Consequently, historical distribution records may be unreliable indicators of current habitat suitability for reintroductions. In this study diurnal behaviour of Arabian oryx was recorded within a central Saudi Arabian reintroduction site. Oryx were less active on warmer days due to an increase in shading (resting in shade) at the expense of feeding time; there was an inverse relationship between temperature and feeding. During hot conditions (maximum ambient temperature >40°C) some individuals spent <2 hours feeding during the day, compared with an average of 4.8 hours during cooler weather. This suggests the importance of shade trees to permit year-round occupancy in reintroduction sites. Selection of sites according to documented historical distribution may focus on tree-less areas, probably formerly part of the winter range. Absence of shade could result in migration out of the reserve, into areas where oryx risk being shot.

Arabian Oryx (Oryx leucoryx) Respond to Increased Ambient Temperatures with a Seasonal Shift in the Timing of Their Daily Inactivity Patterns

“…This suite of behavioural and morpho-physiological features undoubtedly assists the Arabian oryx to survive in the desert of the Arabian Peninsula, although these features appear to be common to all species of oryx living in arid environments and are not specific adaptations of the Arabian oryx (Taylor, 1966;1968, 1969, 1970aTaylor and Lynn, 1972;King et al, 1975;King, 1979;Stanley Price, 1985). Seddon and Ismail (2002) and Hetem et al (2012a) indicate the possibility of an altered daily activity pattern between the cooler (diurnal activity) and hotter (nocturnal activity) months in the Arabian oryx, although this was not explored in detail in either of these studies. Amongst many mammals, the dominant, or primary, zeitgeber for entraining circadian rhythms, including daily activity patterns, is ambient light (e.g.…”

“…Seddon and Ismail (2002) used focal 10 minute observations from 6 am to 6 pm, and Hetem et al (2012a) used a coarse grain method of actigraphy, in their studies, but were not able to clearly show this variation due to the observations either not including the full 24 hour period (Seddon and Ismail, 2002), or the recordings not being made throughout the entire year, with the cooler months of December to March not being recorded (Hetem et al, 2012a). While many studies report seasonal variations of the daily activity patterns, termed temporal niche switching (reviewed in Refinetti, 2008 andHut et al, 2012), from a range of mammalian species, only a few examples of this occurring under natural conditions have been reported.…”

“…In order to cope with this hot and dry environment the Arabian oryx employs a range of behavioural and morpho-physiological responses to high temperatures. During the summer, Arabian oryx have been observed to increase the time spent resting in the shade, where they appear to dig shallow depressions to rest in (Stanley Price, 1989;Seddon and Ismail, 2002), creating a cooler microclimate (Hetem et al, 2012a). In addition to these behavioural strategies, the Arabian oryx has morphophysiological capacities that assist its survival, such as reduced fasting metabolic rates, lower total evaporative water loss rates, lower water influx/turnover rates compared to other similar sized artiodactyls (Williams et al, 2001), adaptive heterothermy (Ostrowski et al, 2003;Hetem et al, 2010) and selective brain cooling (Hetem et al, 2012b).…”

“…Thus, the Arabian oryx may be able to alter its daily activity patterns depending on the season to mitigate the effect of temperature differentials, but it is unclear whether the timing of sleep changes in accordance with the potentially different seasonal daily activity patterns (Seddon and Ismail, 2002;Hetem et al, 2012a). In order to determine whether daily activity patterns and/or the timing of sleep change or remain the same seasonally in the Arabian oryx, we used actigraphy (Ancoli-Isreal et al, 2003) to explore the timing of daily activity patterns and potential sleep periods during both summer and winter months.…”

Effects of an exceptional drought on daily activity patterns, reproductive behaviour, and reproductive success of reintroduced Arabian oryx (Oryx leucoryx)

“…Contrary to our findings, Seddon and Ismail (2000) found an inverse relationship between ambient (air) temperature and feeding, while in our study soil temperature was negatively correlated with feeding. This apparent discrepancy, however, may easily be explained by the fact that soil temperature was not included in Seddon and Ismail's (2002) analysis.…”