A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Prey depletion by the foraging of the Eurasian treecreeper, Certhia familiaris, on tree-trunk arthropods
Tekijät: Jantti A, Aho T, Hakkarainen H, Kuitunen M, Suhonen J
Kustantaja: SPRINGER-VERLAG
Julkaisuvuosi: 2001
Lehti:: Oecologia
Tietokannassa oleva lehden nimi: OECOLOGIA
Lehden akronyymi: OECOLOGIA
Vuosikerta: 128
Numero: 4
Aloitussivu: 488
Lopetussivu: 491
Sivujen määrä: 4
ISSN: 0029-8549
DOI: https://doi.org/10.1007/s004420100677
Tiivistelmä
We examined to what extent breeding insectivorous treecreepers, Certh ia fain ilia ris, affect the abundance and the mean size of their prey population on the surface of tree trunks. In order to determine foraging pressure on tree trunks, we observed the parent birds' foraging behaviour in marked squares (25x25 m) at a short (10 m) and long distance (90 in) from the nest, when the nestlings were near fledging. Immediately after fledging, we measured the remaining food abundance on a sample of tree trunks near to and far from the nest. All arthropods longer than I mm were collected and identified to family level and their length was measured. Treecreepers foraged for significantly less time on trunks far from the nest than on trunks close to the nest (5 s vs 186 s). Consequently, treecreepers were found to deplete food abundance on trunks close to the nest. During the nesting period, parent birds removed almost twice as many spiders and other arthropods (excluding Formica ants) from the tree trunks close to the nest than from those further away. The size distribution of arthropods was the same between frequently and seldom-used tree trunks, suggesting that arthropod consumption by treecreepers was not size selective. Our direct measurements on the abundance of arthropods provide rare evidence for the ability of predators to deplete their food resources to a large extent.
We examined to what extent breeding insectivorous treecreepers, Certh ia fain ilia ris, affect the abundance and the mean size of their prey population on the surface of tree trunks. In order to determine foraging pressure on tree trunks, we observed the parent birds' foraging behaviour in marked squares (25x25 m) at a short (10 m) and long distance (90 in) from the nest, when the nestlings were near fledging. Immediately after fledging, we measured the remaining food abundance on a sample of tree trunks near to and far from the nest. All arthropods longer than I mm were collected and identified to family level and their length was measured. Treecreepers foraged for significantly less time on trunks far from the nest than on trunks close to the nest (5 s vs 186 s). Consequently, treecreepers were found to deplete food abundance on trunks close to the nest. During the nesting period, parent birds removed almost twice as many spiders and other arthropods (excluding Formica ants) from the tree trunks close to the nest than from those further away. The size distribution of arthropods was the same between frequently and seldom-used tree trunks, suggesting that arthropod consumption by treecreepers was not size selective. Our direct measurements on the abundance of arthropods provide rare evidence for the ability of predators to deplete their food resources to a large extent.
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