Long‐term changes in agricultural practices and wildfowling in an internationally important wetland, and their effects on the guild of wintering ducks

Duncan, Patrick; Hewison, A. J. M.; Houte, Sylvie; Rosoux, René; Tournebize, T.; Dubs, Florence; Burel, Françoise; Bretagnolle, Vincent

doi:10.1046/j.1365-2664.1999.00363.x

Cited by 83 publications

(65 citation statements)

References 18 publications

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“…It was about 120,000 birds in 1963-1983(Hollis et al 1986), 90,000 birds in 1984-1992 (Dehorter 1997), 121,000 birds in 1993-1994 (Tamisier et al 1995), and 60,000 in the present assessment. In theory, regional factors can influence the annual abundance fluctuation of waterbird community whose population abundances depend on reproduction in different geographical areas situated very far apart (Kushlan 1986;Duncan et al 1999). The common species considered in this study, appear not very threatened in their breeding areas (AEWA 1999), and the fluctuation of their abundance in Ichkeul National Park is not related to reproduction.…”

Section: Discussionmentioning

confidence: 87%

Variation of the waterbird community relying to the Ichkeul National Park, Tunisia

2008

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For the period of 2001-2004, the detailed reaction of a waterbird community to dam building has been assessed in the Ichkeul National Park. Results showed that 71 species belonging to 8 orders were detected. Three herbivorous species were largely dominant: common coot (Fulica atra), common pochard (Aythya ferina), and Eurasian wigeon (Anas penelope). The three community parameters used in the analysis were: species richness, species abundance, and species diversity; which were significantly different between seasons. The wintering season was a key phase when the maximum values of these parameters were reached. This seasonal concentration of activity may be explained by migration. The upstream freshwater diversion was followed by a decrease in the annual abundance of the waterbird community due to the increasing salinity and the severe depletion of the swamp grass, Potamogeton (Potamogeton pectinatus). The total number of species was independent of the local conditions, and the annual variation was related to the number of uncommon species seen in each year.

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Section: Discussionmentioning

confidence: 87%

Variation of the waterbird community relying to the Ichkeul National Park, Tunisia

2008

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“…Such long-term habitat modifications can significantly influence habitat utilization, species diversity and population sizes as already shown for various bird species (Duncan et al 1999;Chamberlain et al 2000;Atkinson et al 2002). For gulls, the most crucial changes are in the overall and continuous decline of the total area of pastures for the benefit of tillage as well as the intensification of grassland management, i.e.…”

Section: Discussionmentioning

confidence: 95%

Area utilization of gulls in a coastal farmland landscape: habitat mosaic supports niche segregation of opportunistic species

Schwemmer¹,

Garthe²,

Mundry

2008

Landscape Ecol

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The intensively farmed coastal lowland landscape of Germany, adjacent to the North Sea, provides important foraging opportunities for Blackheaded, Common, Herring and Lesser Black-backed gull (Larus ridibundus, L. canus, L. argentatus and L. fuscus). We expected that spatial and temporal utilization of the landscape mosaic as well as behavioural traits and utilization of food resources would differ between these closely related species, facilitating niche segregation. We recorded habitat types and their utilization by the four species over a whole year. Furthermore, we related species abundance to several abiotic parameters. Black-headed and Common gulls were the most numerous species in the study area throughout the year. In general, the former species preferred bare fields with recently prepared soils and was often associated with tractors in the fields, whereas the latter species was most often found on pastures. Black-headed gulls seem to have a higher ability to exploit ephemeral, food sources associated with human activities whereas common gulls prefer habitats with low human activity and with naturally distributed prey. The most prominent abiotic parameter influencing gull abundance was presence of tractors. Black-headed gulls have most likely benefited from recent changes in agricultural practice, particularly the increase in cropped land, while Common gulls may have suffered from a decline in pastures. At present, utilization of the farmland habitat mosaic leads to niche segregation and supports coexistence, as two of the four gull species mainly forage in the marine environment, while there is significant habitat partitioning between the other two temporally, spatially and behaviourally.

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“…Julliard et al 2003; for ducks see e.g. Bethke & Nudds 1995, Duncan et al 1999. However, in the last two decades, the potential consequences of global climate change for animal populations have emerged as ranking amongst the greatest perceived threats to biodiversity (e.g.…”

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confidence: 99%

Spring migration dates of teal Anas crecca ringed in the Camargue, southern France

et al. 2006

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The policy of the European Commission prohibits hunting of migratory birds while they travel to their breeding grounds. To date, spring migration dates of ducks have mainly been determined using bird counts, but the validity of this sometimes disputed method has never been tested. We used ring-recovery data from close to 9,000 teal Anas crecca ringed in the Camargue, southern France, to determine the onset of spring migration. This method makes it possible to avoid potential biases linked to duck counts, and was used to test the validity of spring migration dates inferred from such counts. Depending on the type of analysis (intra-or inter-annual recoveries), teal appeared to start migrating from the Camargue during the first or second 10-day period of January, with no significant differences between years, and no effect of the bird's age or sex. However, when taking potential winter dispersion into account, we suggest that a conservative estimate for the onset of spring migration is the first 10-day period of February. Migration dates inferred from ring-recovery analyses were consistent with earlier results from duck counts, and provide a firm basis for policy making related to hunting. Though ringing data should be preferred when available, our study suggests that determining migration dates from bird counts may be a reliable method for teal, and potentially for other dabbling and diving ducks as well.

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Long‐term changes in agricultural practices and wildfowling in an internationally important wetland, and their effects on the guild of wintering ducks

Cited by 83 publications

References 18 publications

Variation of the waterbird community relying to the Ichkeul National Park, Tunisia

Variation of the waterbird community relying to the Ichkeul National Park, Tunisia

Area utilization of gulls in a coastal farmland landscape: habitat mosaic supports niche segregation of opportunistic species

Spring migration dates of teal Anas crecca ringed in the Camargue, southern France

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