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

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.