| 1. |
- Hjernquist, Marten B., et al.
(author)
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Sex allocation in response to local resource competition over breeding territories
- 2009
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In: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 20:2, s. 335-339
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Journal article (peer-reviewed)abstract
- Sex allocation according to local resource competition suggests that investment and offspring sex ratio should be biased toward the dispersing sex to limit the competition among the natal philopatric sex. Conversely, when competition over resources is low, parents should allocate more resources toward the philopatric sex. In this study, this reciprocal scenario of sex allocation is tested. More specifically, the effect of breeding territory availability on primary sex ratio is studied in the collared flycatcher, a migratory passerine bird, where males are the natal philopatric sex. As predicted, primary sex ratios were biased toward males in areas where available territories were abundant (estimated from population growth). No relationship between sex ratio adjustment and adult phenotypes as well as date of first egg was found. We discuss potential explanation for the male-biased broods in areas with many vacant territories and low levels of competition. We suggest that sex ratio adjustment in relation to breeding territory quality and availability could be relatively common in birds.
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| 2. |
- Forsman, Jukka T., et al.
(author)
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Competitor density cues for habitat quality facilitating habitat selection and investment decisions
- 2008
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In: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 19:3, s. 539-545
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Journal article (peer-reviewed)abstract
- The theory of species coexistence predicts avoidance between species that compete for similar resources. Recent studies, however, have suggested that facilitation is also possible if competitor density provides information about resources. Optimal solution to trade-off between competition and facilitation is predicted to occur at intermediate competitor densities. We tested this hypothesis by experimentally creating a density range of resident tit species (Parus spp.), and measured the response of a competitively subordinate migratory bird, the collared flycatcher (Ficedula albicollis) in terms of habitat preference (settlement order and density), offspring investment (clutch size and primary sex ratio of offspring), and reproductive success (number and condition of nestlings). We show that most habitat choice and investment decisions of flycatchers were unimodally related to tit density, whereas reproductive success decreased linearly with increasing density. Flycatchers thus made mismatched investment decisions at the artificial tit densities because manipulation disassociated the natural correlation between habitat quality and population density. Apparently low and high tit densities were perceived as indication of poor quality habitat in terms of low amount or quality of resources/high mortality risk and high costs of competition, respectively. This demonstrates that competitor density can be used in assessing overall habitat quality in habitat selection and offspring investment decisions, integrating information on resources and competition.
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| 3. |
- Hjernquist, Marten B., et al.
(author)
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High individual repeatability and population differentiation in stable isotope ratios in winter-grown collared flycatcher Ficedula albicollis feathers
- 2009
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In: Journal of Avian Biology. - 0908-8857 .- 1600-048X. ; 40:2, s. 102-107
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Journal article (peer-reviewed)abstract
- For migrants, we often lack complete information of their spatial distribution year round. Here, we used stable carbon, nitrogen and hydrogen isotope ratios extracted from feathers grown at the wintering sites of the long-distance migratory collared flycatcher Ficedula albicollis, to study how individuals from different breeding populations are distributed at the wintering sites. A sub-sample of birds was also sampled in two consecutive years to test for the repeatability of isotope ratios. Birds from the same breeding populations had more similar isotope ratios compared to birds from other nearby populations (10-100 km apart). Furthermore, isotope repeatability within individuals was high, implying that the observed pattern of isotope variation is consistent between years. We put forward two hypotheses for these patterns; 1) strong wintering site philopatry and migratory connectivity, suggesting that migratory connectivity may potentially be found on a much smaller spatial scale than previously considered, and 2) consistent interpopulation differentiation of feeding ecology at their wintering site.
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| 4. |
- Veen, Thor, et al.
(author)
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Identifying the African Wintering Grounds of Hybrid Flycatchers Using a Multi-Isotope (delta H-2, delta C-13, delta N-15) Assignment Approach
- 2014
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:5, s. e98075-
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Journal article (peer-reviewed)abstract
- Migratory routes and wintering grounds can have important fitness consequences, which can lead to divergent selection on populations or taxa differing in their migratory itinerary. Collared (Ficedula albicollis) and pied (F. hypoleuca) flycatchers breeding in Europe and wintering in different sub-Saharan regions have distinct migratory routes on the eastern and western sides of the Sahara desert, respectively. In an earlier paper, we showed that hybrids of the two species did not incur reduced winter survival, which would be expected if their migration strategy had been a mix of the parent species' strategies potentially resulting in an intermediate route crossing the Sahara desert to different wintering grounds. Previously, we compared isotope ratios and found no significant difference in stable-nitrogen isotope ratios (delta N-15) in wintergrown feathers between the parental species and hybrids, but stable-carbon isotope ratios (delta C-13) in hybrids significantly clustered only with those of pied flycatchers. We followed up on these findings and additionally analyzed the same feathers for stable-hydrogen isotope ratios (delta H-2) and conducted spatially explicit multi-isotope assignment analyses. The assignment results overlapped with presumed wintering ranges of the two species, highlighting the efficacy of the method. In contrast to earlier findings, hybrids clustered with both parental species, though most strongly with pied flycatcher.
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