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| 2. |
- Härdling, Roger, et al.
(författare)
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Memory for hoarded food : An aviary study of the european nuthatch
- 1997
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Ingår i: The Condor: ornithological applications. - : Oxford University Press (OUP). - 0010-5422. ; 99:2, s. 526-529
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Tidskriftsartikel (refereegranskat)abstract
- In an aviary study, each of six male European Nuthatches Sitta europaea was allowed to hoard 30 sunflower seeds in natural hoarding substrates. After eight days, each bird was allowed to search for its cached seeds and its performance compared with that of a bird without previous experience of the specific aviary. In all but one case, the hoarder found significantly more seeds than did the naive bird and the hoarder also found the first seed significantly sooner. Furthermore, hoarders found a fixed number of seeds more quickly than did naive birds. These results suggest memory of cache sites.
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| 3. |
- Merilä, Juha, et al.
(författare)
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Interspecific Competition for Nest Holes Causes Adult Mortality in the Collared Flycatcher
- 1995
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Ingår i: The Condor. - : Oxford University Press (OUP). - 0010-5422 .- 1938-5129. ; 97:2, s. 445-450
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Tidskriftsartikel (refereegranskat)abstract
- Interspecific competition for nest sites between tits (Parus spp.) and Collared Flycatchers (Ficedula albicollis) was responsible for the death of 23 flycatchers during one breeding season. Eighteen (78%) of the killed flycatchers were males, and nineteen (83%) of the kills took place in nest boxes occupied by Great Tits (Parus major), and two (9%) in boxes occupied by Blue Tits (P. caeruleus). The number of casualties in different plots increased with increasing proportion of nest boxes occupied by tits (r = 0.76), and decreased with increasing density of nest boxes (r = -0.43). The number of casualties equalled up to 17% of all flycatcher individuals breeding in a given plot, indicating that interspecific competition for nest sites may constitute a significant source of adult mortality in the Collared Flycatcher population studied.
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| 4. |
- Olsson, O, et al.
(författare)
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Changes in King Penguin breeding cycle in response to food availability
- 1997
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Ingår i: CONDOR. - : COOPER ORNITHOLOGICAL SOC. - 0010-5422. ; 99:4, s. 994-997
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- From 1991 to 1996 we investigated how the breeding cycle of King Penguins Aptenodytes patagonicus, in a small colony at South Georgia, was affected by variation in food availability between years. During the first (1992) and third (1996) of the three succ
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| 5. |
- Svensson, E, et al.
(författare)
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Molt and migratory condition in Blue Tits: A serological study
- 1996
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Ingår i: CONDOR. - : COOPER ORNITHOLOGICAL SOC. - 0010-5422. ; 98:4, s. 825-831
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Migration and molt are both energy demanding activities and can be expected to conflict with each other in migratory birds. We studied autumn migrating juvenile Blue Tits (Parus caeruleus) and investigated whether molting birds showed signs of diseases or
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