The role of reed management and habitat quality on brood parasitism and chick survival of the brood parasitic Common Cuckoo

Abstract

Despite efforts on ecosystem restoration and management, biodiversity loss remains one of the major environmental concerns of our time. Beyond the focus on threatened species, animals that indicate regional biodiversity hotspots and population trends, such as brood parasites, should also be targeted by conservation actions. We studied how reed habitat quality and management influence brood parasitism rate and offspring survival in Common Cuckoos Cuculus canorus parasitizing nests of Great Reed Warblers Acrocephalus arundinaceus in six reed habitats in an intensive agricultural landscape. Data collected from 45 sites over 13 years showed that the brood parasitism rate was highest on large canals and was positively influenced by the availability of potential perches (Cuckoo vantage points) and the height where host nests were built. Cuckoo chick survival decreased with water depth and was not affected by other factors. Our results suggest that the habitat‐dependent detectability of host nests was central in brood parasitism rate and that water level was central in Cuckoo chick survival. Our study shows that a maintenance of intermediate water levels is the most optimal for maintaining Cuckoo populations in intensive agricultural landscapes. Because brood parasites are excellent bioindicators as their presence predicts regional hotspots of taxonomic and functional diversity as well as population trends in bird communities, knowledge on their habitat requirements is relevant in management targeting diverse bird communities.

Reuse of nests in the Great Reed Warbler Acrocephalus arundinaceus: A behavior to save time and energy and to deter nest parasites?

“…The reuse of the nest and the laying of new eggs among the old eggs may be similarly explained as in the case of MP, i.e., to save time and energy. In addition, we believe that in this case the high pressure of brood parasitism by Cuckoos in the VBC (parasitism rate c. 40%, Mérő et al, in revision), also played a role. In highly parasitized populations, Great Reed Warblers tend to develop strategies such as egg recognition and ejection to defend against brood parasitism (Moskát et al, 2008).…”