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Factor determining prochard nest predation along a wetland gradient

Journal of Wildlife Management

By:
, , , , , and
DOI: 10.2193/0022-541X(2006)70[784:FDPNPA]2.0.CO;2

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Abstract

Waterfowl management on breeding grounds focuses on improving nest success, but few studies have compared waterfowl nest success and factors affecting nest survival along a wetland gradient and simultaneously identified nest predators. We monitored nests (n = 195) of common pochards (Aythya ferina) in Trebon Basin Biosphere Reserve, Czech Republic, during 1999-2002. Daily nest survival rates (DSRs, logistic-exposure) declined from island (0.985, 95% confidence interval, 0.978-0.991) to overwater (0.962, 0.950-0.971) and terrestrial (0.844, 0.759-0.904) nests. The most parsimonious model for DSRs included habitat class (DSRs: island > overwater > terrestrial) and nest visibility. Nest survival was improved by reduced nest visibility, increased water depth, and increased distance from the nest to habitat edge in littoral habitats. On islands, nest success increased with advancing date and increased distance to open water. A model of constant nest survival best explained the data for terrestrial nests. There were no observer effects on DSRs in any habitat. In 2003, artificial nests (n = 180; 120 contained a wax-filled egg) were deployed on study plots. The model that best explained variation in DSRs for artificial nests included only 1 variable: habitat class (DSRs: island ??? overwater > terrestrial). Mammalian predation of artificial nests (by foxes [Vulpes vulpes] and martens [Martes spp.]) was more likely in terrestrial habitats than in littoral habitats or on islands. By contrast, corvids and marsh harriers (Circus aeruginosus) prevailed among predators of overwater and island nests. Our data indicate that artificial islands and wide strips of littoral vegetation may represent secure breeding habitats for waterfowl because those habitats allow nests to be placed in areas that are not accessible to, or that are avoided by, mammalian predators. Management actions should be aimed at preserving these habitats. This, along with creation of new artificial islands, could help to enhance breeding productivity of pochards and possibly other waterfowl species inhabiting man-made ponds.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Factor determining prochard nest predation along a wetland gradient
Series title:
Journal of Wildlife Management
DOI:
10.2193/0022-541X(2006)70[784:FDPNPA]2.0.CO;2
Volume
70
Issue:
3
Year Published:
2006
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Wildlife Management
First page:
784
Last page:
791