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<p>The population of Somali Ostrich (<i>Struthio molybdophanes</i>) is rapidly declining due to ongoing threats, such as hunting, egg collection, habitat loss, and degradation. Conservation efforts are hampered by inadequate information, partly because the Somali Ostrich was only recently recognised (in 2014) as a distinct species. This study investigated seasonal variation in foraging intensity of Somali Ostriches across different habitat zones in Lewa and Borana conservancies, Samburu County, Kenya. We considered two seasons (wet and dry) and three habitat zones (open grasslands, open woodlands, and riverine). First, we characterised the habitat zones in terms of herbaceous vegetation cover, grass height, and productivity (using normalised difference vegetation index, NDVI) during both seasons. Second, we examined seasonal differences in the foraging intensity of individual ostriches within each habitat zone. For behavioural observations, we used focal sampling, continuously observing individual birds for 5-min bouts and recording foraging behaviours. Foraging behaviours were defined as feeding (pecking, hereafter referred to as ‘bites’) and movement in search of food (‘steps’). We made a total of 42 focal samples in open grasslands, 35 in open woodlands, and 33 in the riverine habitat. Herbaceous vegetation cover and grass height were consistently higher in the wet season than in the dry season across all habitat zones. Step rate was significantly higher in open woodlands during the wet season, whilst bite rate was significantly higher in open grasslands during the dry season. No seasonal differences in foraging activity were observed in riverine habitats. Bite rate was negatively correlated with grass height, whilst herbaceous cover negatively influenced bites per step. These findings suggest that Somali Ostriches adjust their foraging behaviour both seasonally and according to habitat type. Although the mechanisms underlying this behavioural plasticity remain unclear, our results demonstrate that Somali Ostriches can persist in variable environments by altering the time allocated to searching for and handling food.</p>

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Seasonal variation in the foraging intensity of Somali Ostrich (Struthio molybdophanes) at different habitat zones in a semi-arid savanna, Kenya

  • 期刊论文

  • 发表日期：

    2025年12月19日

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  • Eunice W. Kamau,
  • Duncan M. Kimuyu,
  • George G. Ndiritu

摘要

The population of Somali Ostrich (Struthio molybdophanes) is rapidly declining due to ongoing threats, such as hunting, egg collection, habitat loss, and degradation. Conservation efforts are hampered by inadequate information, partly because the Somali Ostrich was only recently recognised (in 2014) as a distinct species. This study investigated seasonal variation in foraging intensity of Somali Ostriches across different habitat zones in Lewa and Borana conservancies, Samburu County, Kenya. We considered two seasons (wet and dry) and three habitat zones (open grasslands, open woodlands, and riverine). First, we characterised the habitat zones in terms of herbaceous vegetation cover, grass height, and productivity (using normalised difference vegetation index, NDVI) during both seasons. Second, we examined seasonal differences in the foraging intensity of individual ostriches within each habitat zone. For behavioural observations, we used focal sampling, continuously observing individual birds for 5-min bouts and recording foraging behaviours. Foraging behaviours were defined as feeding (pecking, hereafter referred to as ‘bites’) and movement in search of food (‘steps’). We made a total of 42 focal samples in open grasslands, 35 in open woodlands, and 33 in the riverine habitat. Herbaceous vegetation cover and grass height were consistently higher in the wet season than in the dry season across all habitat zones. Step rate was significantly higher in open woodlands during the wet season, whilst bite rate was significantly higher in open grasslands during the dry season. No seasonal differences in foraging activity were observed in riverine habitats. Bite rate was negatively correlated with grass height, whilst herbaceous cover negatively influenced bites per step. These findings suggest that Somali Ostriches adjust their foraging behaviour both seasonally and according to habitat type. Although the mechanisms underlying this behavioural plasticity remain unclear, our results demonstrate that Somali Ostriches can persist in variable environments by altering the time allocated to searching for and handling food.