Seasonal variations in locomotor activity rhythm and diurnal activity in the dromedary camel (Camelus dromedarius) under mesic semi-natural conditions

Abstract

The dromedary camel (Camelus dromedarius) is a large ungulate that copes well with the xeric environment of the desert. Its peculiar adaptation to heat and dehydration is well-known. However, its behavior and general activity is far from being completely understood. The present study was carried out to investigate the ecological effect of the various seasons on the locomotor activity (LA) rhythm and diurnal activity of this species. Six adult female camels were maintained under mesic seminatural conditions of the environment during four periods of 10 days in each season: autumn, winter, spring and summer. In addition, three female camels were used to test the effect of rain on the LA rhythm during a period of 18 days during the winter. The animal's LA was recorded using the locomotion scoring method. Camels displayed a clear 24.0h LA rhythm throughout the four seasons. Activity was intense during Day-time (6-22 fold higher in comparison to night) and dropped or completely disappeared during nighttime. Mean daytime total activity was significantly higher in the summer as compared to winter. Regardless of the season, the active phase in camels coincided with the time of the photophase and thermophase. Furthermore, the daily duration of the time spent active was directly correlated to the seasonal changes of photoperiod. The diurnal activity remained unchanged over the four seasons. For each season, the start and the end of the active phase were synchronized with the onset of sunrise and sunset. At these time periods, temperature remained incredibly stable with a change ranging from 0.002 to 0.210°C; whereas, changes of light intensity were greater and faster with a change from 0.1 to 600 lux representing a variation of 3215-7192 fold in just 25-29 min. Rainfall affected the pattern of the LA rhythm with occurrence of abnormal nocturnal activity during nighttime disturbing nocturnal rest and sleep. Here we show that the dromedary camel exhibits significant seasonal changes of its activity within daylight hours. However, the diurnal pattern remains unchanged regardless of the season; whereas, abnormal nocturnal activity is observed during periods of rain. The activity onset and offset in this species seems to be primarily driven by the changes in light intensity at dusk and dawn.

Effect of age, season, and gender on bronchoalveolar lavage fluid cytology in camels

“…However, it may be difficult to evaluate and compare the effect of the annual season between camels and other animal species because of the way free camels are raised in the desert and their exposure to weather factors directly ( Abdelhadi et al ., 2012 ). It is known that camels live outdoors in a desert environment all year round and are exposed to sharp changes in weather between summer and winter, which may have a significant impact on the response of the respiratory system ( Ibrahim and Al-Kheraije, 2021 ; Farsi et al ., 2022 ). On the other hand, most animal species are arranged indoors during harsh seasons, which makes a comparison of the effect of weather on respiratory response and the percentage of cells in alveolar wash samples challenging to compare.…”

Temporal niche partitioning among sympatric wild and domestic ungulates between warm and cold seasons

“…Therefore, seasonal variation is a critical influence on daily activity patterns, especially apparent in wild mammals 23 , 24 . Moroccan dromedary camels ( Camelus dromedarius ) showed increased nocturnal activity during rainfall to take advantage of lower temperatures and better food resources 25 . In the Apennines of central Italy, European roe deer ( Capreolus capreolus ) increase nocturnal activity in summer to regulate body temperature and synchronize reproduction 17 .…”