Multidimensional Foraging Niche Organization of Foliage-Gleaning Birds in Northern Finland

Publication Type:Journal Article
Year of Publication:1982
Authors:Alatalo, RV
Journal:Ornis Scandinavica
Date Published:1982
ISBN Number:00305693
Keywords:Certhia, Certhia familiaris, Certhiidae, Finland, Fringilla, Fringilla coelebs, Fringillidae, Montifringilla, Paridae, Parus, Parus montanus, Phylloscopidae, Phylloscopus, Phylloscopus trochilus, Poecile, Poecile montanus, Regulidae, Regulus, Regulus regulus, Trochilus
Abstract:Six foraging niche dimensions (habitat, tree species, tree size, height in tree, tree part, feeding posture) were studied and multidimensional niche overlaps and breadths, which take into account the most important dependencies between niche axes, were calculated. The species studied were: Parus montanus, P. cristatus, P. major, P. ater, Phylloscopus trochilus, Fringilla coelebs, F. montifringilla, Regulus regulus and Certhia familiaris. The six-dimensional niche overlaps between common foliage-gleaning birds were 0.35-0.62, indicating relatively regular spacing of species in the multidimensional space, where all species overlap with one another in roughly the same proportions. Tree part was the most important axis for niche separation, perhaps owing to its close association with body size. The two most important axes, tree species and tree part, explained 77% of six-dimensional foraging niche differences in summer and up to 87% in winter. Foraging niche overlap was lower in winter than in summer, perhaps to avoid interspecific competition for limited food resources in winter. Resident foliage-gleaners were small and able to use versatile postures and to exploit needled twigs. Summer visitors, at least partly, used resources rejected by residents (deciduous trees, low trees). Niche width with respect to foraging site decreased in winter, but posture versatility increased. Fewer foraging sites are profitable for birds in winter, but since food is scarce birds cannot be very selective within each foraging site; hence broad niche for microaxes, such as foraging posture. True multidimensional niche overlaps or breadths could not be estimated adequately by one-dimensional projections (summation or production).
Short Title:Ornis Scandinavica
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith