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 following.

Action Category

Alter artificial nest sites to discourage brood parasitism

Action Link
Bird Conservation

Remove/control adult brood parasites

Action Link
Bird Conservation
  1. Alter artificial nest sites to discourage brood parasitism

    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’.


  2. Remove/control adult brood parasites

    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’.


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