Abstract

GALLINA, Sonia  and  BELLO GUTIERREZ, Joaquin. Activity Patterns of White-tailed deer in Northeastern Mexico. Therya [online]. 2014, vol.5, n.2, pp.423-436. ISSN 2007-3364.  https://doi.org/10.12933/therya-14-200.

Introduction: Animals' requirements and their complex interactions with their environment result in different activity patterns that reflect adaptations to daily, seasonal and annual variations in their surroundings. These adaptations may differ among individuals as a function of age, sex, physiological state, time of day, season and weather. Behavior is important because deer tend to voluntarily avoid unpleasant environmental circumstances, such as extreme heat or cold, and wind. Most animals divide their time between two fundamentally different types of behavior: activity and rest. All deer species have a unique way of spending their time and energy to maximize their fitness. Studies of behavioral thermoregulation in ungulates report a reduction in activity and an increase in rest in ruminant species on days when the temperature is high. This suggests that deer are bedding during the day and foraging at night when the temperature is lower. In northeastern desert scrub in Mexico, the activities of white-tailed deer were documented over four years to establish whether activity and behavior patterns change with variations in the environment as a result of the quantity and distribution of annual precipitation. Methods: This research was carried out at Rancho San Francisco (27° 19' 36"- 27° 22' 24" N, 100° 36' 23"- 100° 39' 01" W: 1,000 ha) located in northeastern Mexico. Climate is semiarid with 400 mm average annual rainfall. From September 1994 to November 1997 a total of 14 females and 9 males were captured, and each was fitted with a radio collar with an activity sensor. Deer location was determined with TR-4 receivers, portable type H and fixed 4-element parallel Yagi, null peak type antennas. Animal location was determined simultaneously by two people every hour over 24 hour cycles, with 2-3 monthly cycles over four years. Each time a deer was located its main behavior pattern was noted based on the number of beeps emitted by the tracking equipment over 5 minutes (bedding, moving, feeding). Results: A total of 243 cycles for females and 170 cycles for males were obtained and analyzed. Deer generally spent more than 12 h bedding, and females were more active than males. There were significant differences in some behavior patterns of the deer for some years and between sexes, though a crepuscular pattern was found for allfour years. There was a significant difference in bedding for females between 1995 and 1997 (P = 0.013), and for males 1995 between and 1998 (P = 0.058). Between sexes, there were significant differences in activity cycles for 1995 (P = 0.012) and 1998 (P = 0.058), and significant differences between sexes in moving behavior during 1998 (P = 0.012). There was a strong correlation between annual precipitation and some variables by sex (Table 3): females and males responded differently. Females had high positive values for feeding (r = 0.97), but negative values for movement (r = -0.085), indicating that they spent more time feeding and less time moving in years with more rainfall and thus more food available. In contrast, males (r = -0.92) rest more in years with less precipitation, or more pronounced drought conditions. Discussion and Conclusions: We found females were more active than males though for both sexes the annual pattern was crepuscular. Females increased foraging time from 10 % (1995) to 20 % (1998) when the rains were delayed in 1998 and almost all their fawns died. Studies of behavior in ungulate browsers have shown that animals reduced their activity and increased bedding time during high daytime temperatures suggesting that deer rest during the hottest hours of the day, and forage at night when it is cooler. Some authors found a significant negative correlation between the periods the deer were active throughout the day and temperature. We conclude that white-tailed deer have a bimodal activity pattern and are most active at dawn and dusk, though this may change with environmental conditions. Some years there are significant differences in their 24 h activity cycle, indicating their adaptability to changing environmental factors in semiarid conditions, such as forage availability as determined by the quantity of rain.

Keywords : bedding; behavior patterns; desert scrub; feeding; moving; radiotelemetry.

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