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Providing evidence to improve practice

Individual study: Nest boxes enhance yellow-shouldered blackbird Agelaius xanthomus fledging success at Boquerón Forest, Puerto Rico

Published source details

Wiley J.W., Post W. & Cruz A. (1991) Conservation of the yellow-shouldered blackbird Agelaius xanthomus, an endangered West Indian species. Biological Conservation, 55, 119-138

This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Alter artificial nest sites to discourage brood parasitism Bird Conservation

A replicated trial in 1980 in Puerto Rico (Wiley et al. 1991) found that, shiny cowbirds Molothrus bonariensis parasitised yellow-shouldered blackbird Agelaius xanthomus nests in all 16 nest box types tested with 96% of 103 nests parasitised. The effect of cowbird control is discussed in ‘Threat: Invasive and other problematic species - Remove/control brood parasites’.


Remove/control adult brood parasites Bird Conservation

A replicated trial in 1980 in Puerto Rico (Wiley et al. 1991) as part of the same study as in (López-Ortiz et al. 2002 and López-Ortiz et al. 2006) found that parasitism of yellow-shouldered blackbird Agelaius xanthomus nests was significantly lower in two mangrove forest sites where shiny cowbirds Molothrus bonariensis were removed, compared to sites where cowbirds were not removed (45% of 11 nests parasitized where all cowbirds were removed vs. 30% of ten where female cowbirds were removed; 67% of nine where males were removed and 92%  of 12 in control sites). This study also investigated the impact of different nest boxes on parasitism, discussed in ‘General responses to small/declining populations - Provide artificial nesting sites’.