During autumn, many migratory passerines that fly from their breeding grounds in Europe and Asia to wintering grounds in Africa stop over in Israel. Their ability to replenish energy sources during stopover has an important effect on their survival. Therefore, high abundance of migrants is expected to occur in rich-food stopover sites. During autumn 1998, I studied the distribution of migratory passerines in two Atlantic pistachio groves in the southernmost margins of the Lahav Wood in the northern Negev. The size of each grove was 3 ha, and the distance between them was 1 km. One grove had an abundance of fruit, whereas the other had not. Two groups of migrating passerines that feed on pistachio fruits were studied: warblers (genus Sylvia) and small thrushes (family Turdidae). Warblers fed mostly on fruits while thrushes fed mostly on arthropods. More fruits were eaten in the shaded north-facing side of the trees than in the south-facing side. In the fruit-rich grove, I found a higher density of both fruits and total birds (warblers and thrushes) throughout the research season. In the fruit-rich grove, trees showed a negative correlation between fruit and foliage densities. Warblers spent most of their time in richly foliated and poor-fruit trees rather than in rich-fruit and poorly foliated trees. The results suggest that while selecting microhabitat, birds react more intensively to predation risk than to fruit abundance. It is possible that a migratory passerine that stops over in a fruit-rich grove may reach its optimum energetic gain in a very short period of feeding time and will choose to spend most of the time sheltered from predation.
|Number of pages||2|
|Journal||Israel Journal of Zoology|
|State||Published - 2000|
ASJC Scopus subject areas
- Animal Science and Zoology