Action: Foster eggs or chicks of woodpeckers with wild conspecifics
- Three studies from the USA found that red-cockaded woodpecker Picoides borealis chicks fostered to conspecifics had high fledging rates.
- One small study found that fostered chicks survived better than chicks translocated with their parents.
Natural variations in reproductive output can be detrimental when populations are very small, for example if pairs fail to produce fertile eggs or some pairs repeatedly fail to raise offspring successfully. One way to minimise this problem is to foster eggs and chicks between nests. Eggs and chicks from nests with more offspring than they are likely to be able to raise can be moved to those with infertile eggs. Alternatively, if a pair produces fertile eggs or healthy chicks but consistently fails to raise chicks then it may be possible to transfer offspring to a more successful pair.
In other circumstances it may be possible to foster chicks with other species (‘cross-fostering’). Studies describing this intervention are discussed in the following section ‘Foster eggs or chicks with wild non-conspecifics (cross-fostering).’
Supporting evidence from individual studies
A small study in loblolly Pinus taeda and longleaf P. palustris pine forests in South Carolina, USA (Franzred 1999), found that all three red-cockaded woodpecker Picoides borealis nestlings translocated with their parents died, whereas two nestlings fostered to wild pairs in the release site were successfully raised. One (a female) disappeared after months, the other (a male) successfully bred. This study is discussed in more detail in ‘Translocate individuals’.
A small study in a pine forest site in Mississippi, USA, in 1996 (Richardson et al. 1999), found that two orphaned red-cockaded woodpecker Picoides borealis nestlings introduced into two foster nests fledged successfully (along with the non-fostered nestlings) and that at least one survived to the following breeding season (when it remained at its foster cluster as a helper). The chicks were both male and fostered when approximately 11 days old into broods containing a single nestling. One was added to the nest with the nestling still present, the other was added whilst the nestling was temporarily removed, to ensure the parents fed the foster chick. Between removal from their nest holes and fostering (later the same day), the chicks were supplied with mealworms and crickets.
A replicated, paired site study from April-July in 1997-1998 in 20 experimental and 18 control (containing 22 nestlings) red-cockaded woodpecker Picoides borealis nests in 5 forest sites in Louisiana, USA (Wallace & Buchholz 2001), found that fostered nestlings exhibited similar fledging rates to native nestlings in the same nests (85% of 20 fostered and 86% of 22 native nestlings fledged) and nestlings in control nests (68% of 22 control nestlings fledging). On average, fostered nests produced more fledglings than control nests (1.8 compared to 1.3 fledglings / nest). Feeding rates for fostered and native nestlings were similar. Cross-fostered nestlings were matched by age. Native and control nestlings were handled and returned to their native nests.
- Franzreb K.E. (1999) Factors that influence translocation success in the red-cockaded woodpecker. Wilson Bulletin, 111, 38-45
- Richardson D.M., Copeland M. & Bradford J.W. (1999) Translocation of orphaned red-cockaded woodpecker nestlings. Journal of Field Ornithology, 70, 400-403
- Wallace M.T. & Buchholz R. (2001) Translocation of red-cockaded woodpeckers by reciprocal fostering of nestlings. The Journal of Wildlife Management, 65, 327-333