| 1. |
- Dessborn, Lisa, 1976-, et al.
(författare)
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Innate responses of mallard ducklings towards aerial, aquatic and terrestrial predators
- 2012
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Ingår i: Behaviour. - Leiden, Netherlands : Brill Academic Publishers. - 0005-7959 .- 1568-539X. ; 149:13-14, s. 1299-1317
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Tidskriftsartikel (refereegranskat)abstract
- Reproductive success in ducks is strongly influenced by predation on the breeding grounds. Ducklings are targeted by a range of terrestrial, aerial and aquatic predators, giving a strong selective advantage to individuals and broods that have effective ways to avoid predation. In experiments on naive mallard (Anas platyrhynchos) ducklings without an accompanying adult female we investigated the innate ability to identify and avoid threats at varying intensity from aerial, aquatic and terrestrial predators. Ducklings displayed increased vigilance in response to pre-recorded calls of predatory birds, representing a low level of threat. They did not react to visual and olfactory stimuli generated by motionless northern pike (Esox lucius). Neither did they show a strong response to caged American mink (Neovison vison) (visual and olfactory stimuli), although they avoided the area with the mink, indicating a certain level of recognition. High intensity threats were simulated by staging attacks from aerial (goshawk, Accipiter gentilis) and aquatic predators (northern pike). The aerial attack made ducklings dive and scatter under water, whereas the response to attack by pike was to run on the water and scatter in different directions. The lack of response to a ‘passive’ pike and the rather weak avoidance of mink indicate that olfactory cues are not as important in identifying a potential predatory threat by ducklings as are auditory cues. Visual cues appear to be of little importance unless they are combined with movement, and a clear response is only triggered when the intensity of predator threat is high. Mallard ducklings, thus, show an innate capacity to adjust anti-predator behaviour to different predator types and to threat intensity. Our study highlights the general trade-off between foraging needs and predator avoidance, but also second-order trade-offs in which innate avoidance behaviour towards one type of predator may increase predation risk from another.
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| 2. |
- Arzel, Céline, et al.
(författare)
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Are ducks able to adapt their migratory habits to environmental change?
- 2010
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Ingår i: The abstract book. ; , s. 25-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In order to predict waterfowl population changes due to variation in climate conditions, and habitat availability it is necessary to precisely understand the mechanisms driving their annual cycle. This is particularly challenging in migratory birds as they encounter a huge variety of habitats along their migratory routes, and different factors might affect their demographic parameters at different stages of their life-cycle. In this perspective spring migration stands out as a crucial period. During spring migration birds need both to complete their migration and to prepare for subsequent reproduction. An understanding of long-term factors influencing the timing of breeding in migratory birds is particularly important in order to predict how they might respond to future environmental changes. Anatidae are particularly interesting to study as they offer a wide variety of migratory strategies. We discuss some of the factors that are likely to affect individual choices and thus play a role in the evolution of migration. Based on long-term data sets, collected over 30 years, in the Archipelago Sea, SW Finland, we also offer a first insight into the changes in their spring arrival and breeding success of ducks in relation to environmental conditions.
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| 3. |
- Arzel, Céline, et al.
(författare)
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Average mass of seeds encountered by foraging dabbling ducks in western Europe
- 2007
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Ingår i: Wildlife Biology. - 0909-6396 .- 1903-220X. - 0909-6396 ; 13:3, s. 328-336
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Tidskriftsartikel (refereegranskat)abstract
- Many dabbling ducks Anas spp. are largely granivorous, consuming a variety of seeds chiefly from aquatic plants. To assess the relative value and carrying capacity of wetlands for dabbling ducks, species-specific information about seed mass is needed, but it is still largely missing or scattered in the literature. By combining weights of seeds collected in the field with a literature review, we provide a reference table for seed mass of 200 western European plant taxa frequently encountered by foraging dabbling ducks. Seeds collected in the field were sampled in microhabitats and at depths at which ducks were observed to forage, and study sites represent wintering, staging as well as breeding areas within a flyway in western Europe. When combined with calorimetric data, the present reference table will aid managers and scientists in assessing the importance of seed food resources at different sites and during different parts of the annual cycle.
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| 4. |
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| 5. |
- Arzel, Céline, et al.
(författare)
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Does changing spring phenology affect short and long distance migratory waterfowl similarly?
- 2010
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Ingår i: The abstract book. ; , s. 43-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Among waterfowl, most ducks may be considered income breeders due to their small body size and their limited capacity to store energy. Therefore limited access to resources on their breeding grounds is likely to affect their breeding schedule and potentially output. At northern latitudes, ice break up dictates the access to the breeding lakes. An early ice break up allows for early access to the breeding site and its feeding resources, and potentially leading to higher breeding output than after a late ice break up. Short distance migrants are thus more likely to adapt to ice break up conditions than long distance migrants which have to cope with weather conditions en route and local resource accessibility along the migratory path. Using 20 years of data on breeding phenology and success of 3 species of ducks differing in their migratory strategy - Teal Anas crecca, Mallard Anas platyrhynchos and Common Goldeneye Bucephala clangula - in a watershed in Finland, we test the idea that variation in spring phenology affects the reproductive performance of duck species differently depending on their migration pattern.
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| 6. |
- Arzel, Céline, et al.
(författare)
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Ecology of spring-migrating Anatidae : a review
- 2006
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Ingår i: Journal of Ornithology = Journal fur Ornithologie. - 0021-8375 .- 1439-0361. - 0021-8375 ; 147:2, s. 167-184
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Forskningsöversikt (refereegranskat)abstract
- Spring migration is generally considered as a crucial period of the year for many birds, not the least due to its supposed importance for subsequent breeding success. By reviewing the existing literature for Anatidae (ducks, geese, and swans), we show that little is known about their ecology in spring, although some goose species are exceptions. Another general pattern is that the ecology of Anatidae at staging sites is particularly neglected. Existing studies tend to focus on questions dealing with acquisition of nutrient reserves, whereas almost nothing has been published about stopover habitats, time use, microhabitat use, foraging behaviour, food availability, food limitation, diet selection, and interspecific relationships. Besides summarising present knowledge, we identify taxonomic groups and topics for which gaps of knowledge appear the most evident, thereby also highlighting research needs for the future.
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| 7. |
- Arzel, Celiné, et al.
(författare)
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Experimental functional response and inter-individual variation in foraging rate of teal (Anas crecca)
- 2007
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Ingår i: Behavioural Processes. - 0376-6357 .- 1872-8308. - 0376-6357 ; 75:1, s. 66-71
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Tidskriftsartikel (refereegranskat)abstract
- The functional response, i.e. the change in per capita food intake rate per time unit with changed food availability, is a widely used too] for understanding the ecology and behaviour of animals. However, waterfowl remain poorly explored in this context. In an aviary experiment we derived a functional response curve for teal (Anas crecca) foraging on rice (Oryza sativa) seeds. We found a linear relationship between intake rate and seed density, as expected for a filter-feeder. At high seed densities we found a threshold, above which intake rate still increased linearly but with a lower slope, possibly reflecting a switch from filter-feeding to a scooping foraging mode. The present study shows that food intake rate in teal is linearly related to food availability within the range of naturally occurring seed densities, a finding with major implications for management and conservation of wetland habitats.
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| 8. |
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| 9. |
- Arzel, Céline, et al.
(författare)
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Time use, foraging behavior and microhabitat use in a temporary guild of spring-staging dabbling ducks (Anas spp.)
- 2004
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Ingår i: Ornis Fennica. - 0030-5685. - 0030-5685 ; 81:4, s. 157-168
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Tidskriftsartikel (refereegranskat)abstract
- Dabbling ducks were studied on a eutrophic mid-flyway staging site in spring. Six species made up a temporary guild, in order of decreasing abundance they were: Teal (Anas crecca), Shoveler (A. clypeata), Mallard (A. platyrhynchos), Wigeon (A. penelope), Pintail (A. acuta), and Garganey (A. querquedula). Species richness and total abundance peaked around 20 April, whereas guild evenness was highest after the staging peak. Time use during the staging peak differed between the sexes in Mallard, but not in the other species. Mallard spent the least time foraging, whereas Shoveler and Teal foraged the most. Foraging behavior differed among species; i.e. Wigeon was mainly on land, Shoveler mainly fed from the water surface, whilst Mallard and Teal were more generalist. For the guild as a whole, shallow inshore areas were overused compared to offshore habitats. Microhabitat use of foraging birds differed among species; Pintail and Shoveler mainly fed in the offshore end of the habitat gradient, whereas Teal, Garganey, female Mallard, and especially Wigeon used shallow microhabitats. Teal and female Mallard had the highest overlap in microhabitat use, Shoveler and Wigeon had the least. Abundance of invertebrate prey was low during the staging peak, but increased sharply thereafter. This study indicates that eutrophic mid-flyway sites may offer less food to staging birds than do breeding lakes to which many of them are headed.
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| 10. |
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