Action: Reduce competition between species by providing nest boxes
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A replicated, controlled study from the USA found that providing extra nest boxes did not reduce the rate at which common starlings Sturnus vulgaris usurped northern flickers Colaptes auratus from nests.
If several species are competing for nest sites then it might be possible to reduce this competition by providing a surplus of nesting sites. The more general effects of nest box provision are discussed in ‘General responses to small/declining populations’.
Supporting evidence from individual studies
A replicated, controlled study from March-July in 1994-1996 in 40 experimental and 14 control sites of northern flicker Colaptes auratus nest cavity and nest box pairs in Ohio, USA (Ingold 1998) found that the provision of nest boxes do not deter common starlings Sturnus vulgaris from usurping flicker nest cavities. Overall, 68% of experimental flicker sites lost a total of 42 cavity-nests to starlings in spite of the presence of a nearby flicker nest box, and nine of these pairs lost two or more cavities to starlings. Flicker pairs with starlings fledged significantly less young than pairs without starlings (20% compared to 36% respectively). Flicker pairs without starlings produced significantly larger clutches than pairs with starlings (7.4 compared to 5.4 eggs / nest). Only one flicker pair nested in a nest box rather than a nest cavity. Nest boxes were installed within 0.5-2.0 m of all flicker cavities. Starlings were present in experimental but not control sites.