Agricultural intensification has significantly impacted the habitat structure of agricultural landscapes and is one of the main drivers of biodiversity decline on farmlands. Farmland birds are strongly linked to other farmland biodiversity and are therefore considered good indicators of biodiversity in agricultural habitats, both in open farmland and edge areas. Thus, factors affecting the success of these birds may provide vital information on how to tackle the challenge of halting biodiversity loss on farmlands.
In this thesis, I studied common pheasant (Phasianus colchicus, hereafter pheasant) hens and broods as well as artificial pheasant nests during the breeding season to identify factors affecting the breeding success of pheasants in an agricultural environment in southern Finland.
I found that both bird quality, i.e. wild compared with hand-reared hens, and predator density affected pheasant survival. My results show that even hand-reared pheasants can breed successfully, especially if red fox (Vulpes vulpes) numbers are low, as they are the main predator of pheasant hens.
Following the broods by radio tracking revealed that field margins were an important and preferred habitat. Most observations were made in grain fields, but comparing habitat use to availability showed a significant preference for margins. Margins along grain fields offer an ideal habitat for pheasant broods, which require high-quality arthropod prey and shelter from predation.
A study setup with wildlife camera traps and artificial pheasant nests revealed that an invasive alien species, the raccoon dog (Nyctereutes procyonoides), may be a common predator of ground-nesting bird nests in agricultural landscapes in Finland. The raccoon dog was the most common primary predator at nests and the most frequent predator visiting the signposts that measured the predator density index in the study areas.
Information gained from my study is useful for planning introductions of hand-reared birds, irrespective of whether they are reintroductions of endangered species or introductions of birds for game management purposes. The results show that introductions using hand-reared birds can be successful as long as predation risk is low and other circumstances required for successful brood production are favorable.
Game managers and farmers are encouraged to put more effort into creating better brood-rearing environments for pheasants, which may then benefit other farmland wildlife. Margins along small grain fields may provide arthropod-rich habitats and controlling predators may enhance the nesting success and survival of ground-nesting farmland birds. My results support earlier findings that field margins should be appreciated as vital biodiversity-enhancing elements in the AES measures of the EU Common Agricultural Policy (CAP).
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