| 1. |
- Guillemain, Guillemain, et al.
(författare)
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Multiple tests of the effect of nasal saddles on dabbling ducks : combining field and aviary approaches
- 2007
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Ingår i: Bird Study. - : Taylor and Francis Ltd.. - 0006-3657 .- 1944-6705. ; 54:1, s. 35-45
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Nasal saddles have no negative consequences apart from, under some circumstances, a potential bias in social relationships. Aims To test the effect of nasal saddles on Teal Anas crecca, Wigeon A. penelope, Mallard A. platyrhynchos and Pintail A. acuta. Methods The following features were compared between saddled and unsaddled individuals: body mass change of wild Teal between ringing and first live recovery, pairing probability of wild Teal through the winter, wild Teal and Wigeon time-budgets, captive Mallard and Pintail body mass fluctuations, testosterone levels and dominance in the aviary. Results We generally found no significant difference between values for birds with nasal saddles and control birds. Exceptions were for pairing probability, which was lower for marked Teal during one of the winters, and the proportion of aggressive interactions won by Pintail, which decreased after they were fitted with saddles, while this did not happen in Mallard. Conclusions Nasal saddles are an appropriate general method for marking dabbling ducks. However, saddles may not be appropriate for the study of social relationships in some conditions.
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| 2. |
- Guillemain, Matthieu, et al.
(författare)
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Predation risk constrains the plasticity of foraging behaviour in teals, Anas crecca : a flyway-level circumannual approach
- 2007
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Ingår i: Animal Behaviour. - : Academic Press Inc.. - 0003-3472 .- 1095-8282. ; 73:5, s. 845-854
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Tidskriftsartikel (refereegranskat)abstract
- The trade-off foragers make between predation risk and feeding efficiency is readily studied in dabbling ducks, which have stereotyped feeding methods, some of which prevent predator detection while others do not. Teals forage mostly with only the bill submerged (eyes above the water surface) in winter, but use a broader foraging repertoire in summer. Given the different environments used by teals over the year, it is likely that such a shift is due to changes in diet, but it may also be caused by differences in predation risk between habitats. However, neither predation risk nor teal behaviour has been studied with consistent methods around the year or throughout any of its flyways. Covering wintering, spring-staging, breeding and moulting sites, we combined focal observations of teals and predator flyover data from seven regions ranging from southern France to northern Sweden. Although not apparent at the scale of days within sites, teals indeed relied more on shallow foraging where predation risk was higher, i.e. at wintering sites. Average foraging depth increased gradually from September to August, i.e. from wintering to breeding sites. Foraging bout length of deeply foraging teals did not decrease over the year, suggesting that it is through selection of foraging technique, rather than by the balance between foraging and interruptions, that birds adjust to predation risk. This study highlights behavioural plasticity in response to contrasting selection regimes within a flyway, in dabbling ducks as well as long-distance migrants in general.
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| 3. |
- Guillemain, Matthieu, et al.
(författare)
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Risky foraging leads to cost-free mate guarding in male teal Anas crecca
- 2007
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Ingår i: Journal of Ornithology = Journal fur Ornithologie. - : Springer Science and Business Media LLC. - 0021-8375. ; 148:2, s. 251-254
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Tidskriftsartikel (refereegranskat)abstract
- Mate guarding by males is common in species with long-lasting pair bonds. We tested if the need to guard females affected foraging depth in male teal (Anas crecca), and if they were more vigilant than females when foraging with submerged eyes (preventing monitoring of competing males and predators). These predictions were not supported, suggesting that foraging depth selection is primarily driven by other factors, presumably food related. A likely reason why deeply foraging males did not increase vigilance is that 37.5% of the foraging time was already dedicated to it. The apparent lack of guarding costs in foraging male teal may explain why such small ducks can maintain pair bonds for up to 7 months.
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