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- Champagnon, Jocelyn, et al.
(författare)
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Changes in Mallard Anas platyrhynchos bill morphology after 30 years of supplemental stocking
- 2010
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Ingår i: Bird Study. - 0006-3657 .- 1944-6705. ; 57:3, s. 344-351
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Massive releases of captive-reared Mallard for hunting purposes have been practiced for 30 years. During this period the number of lamellae per centimetre of bill length in wild Mallard populations has decreased. Aims Every year since the 1970s, several million captive Mallard have been released in Europe. This may lead to a spread of unnatural phenotypes into the wild. Nevertheless, the consequences of such introductions have not been examined. Methods Two widespread and common migratory ducks were studied: Mallard Anas platyrhynchos and Teal A. crecca. Mallard is the only duck species for which stocking programmes occur, and Teal served as a control. In a 'before-after' design, we compared duck bill lamellar density over the last 30 years. Results Lamellar density in Mallard, but not Teal, decreased. The observed 10% decrease occurred in the first (proximate) centimetre of the bill, the most crucial in terms of food filtration. Conclusions We hypothesize that the change in bill morphology was because of the propagation of captive Mallard into the wild: captive Mallard eat mainly large items, relaxing the natural selection pressure maintaining high lamellar density for sieving small prey in wild ducks.
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| 2. |
- Champagnon, Jocelyn, et al.
(författare)
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Consequences of massive bird releases for hunting purposes : mallard Anas platyrhynchos in the Camargue, Southern France
- 2009
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Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special issue 2, s. 184-191
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Tidskriftsartikel (refereegranskat)abstract
- The release of captive-reared fish and game animals into the wild is a common management practice in Europe and North America. In Europe, millions of reared birds are released each year yet the consequences of these release programmes have received little attention. This paper describes the massive introduction of Mallard Anas platyrhynchos, a native migrant species released into the wild to increase the size of hunted populations. It provides the rationale for current and forthcoming experiments aimed at determining the effects of the augmentation of Mallard stocks on wild population genotype and survival rates.
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| 3. |
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| 4. |
- Guillemain, Matthieu, et al.
(författare)
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Wintering French mallard and teal are heavier and in better body condition than 30 years ago : effects of a changing environment?
- 2010
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Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 39:2, s. 170-180
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Tidskriftsartikel (refereegranskat)abstract
- Animal populations are exposed to large-scale anthropogenic impact from e.g. climate change, habitat alteration and supplemental stocking. All of these may affect body condition in wintering dabbling ducks, which in turn may affect an individual's survival and reproductive success. The aim of this study was to assess whether there have been morphometric changes in Mallard (Anas platyrhynchos) and Teal (Anas crecca) over the last 30 years at a major wintering site. Body mass and condition increased from the 1950s-1960s to the 2000s in both species. The increase in body mass amounted to as much as 11.7%, with no corresponding change in body size. Improved body condition was maintained from early to mid-winter, but then converged with historical values for late winter. Our interpretation is that increasingly benign ambient winter conditions permit ducks to maintain better energetic "safety margins" throughout winter, and that converging spring departure values may be related to evolutionary flight energetic optima. The observed changes are consistent with large-scale climate amelioration and local/regional habitat improvement (both anthropogenic).
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