GENETIC-EVIDENCE FOR MONOGAMY IN THE COOPERATIVELY BREEDING RED-COCKADED WOODPECKER

We examined the genetic relationship among putative parents, offspring , and helpers in 224 red-cockaded woodpeckers (Picoides borealis) from the Sandhills of North Carolina. Comparison of DNA similarity with a pedigree constructed from 3,823 individually-marked birds observed fro m 1979 to 1992 provided verification of observed relatedness in the sa mpled population (R2 = 0.87, df = 14, P < 0.001). In this population, breeding pairs may or may not have helpers, most of which are males th at remain on their natal territory. Our sample included helpers assist ing their parents, helpers assisting a related male and an unrelated f emale, and helpers assisting an unrelated pair. Band by band compariso n and examination of similarity among DNA profiles indicated that all offspring from non-helped nests were sired by their putative parents ( n = 28 families). Similarly, all but one offspring in helped nests wer e also sired by their putative parents (n = 16 families). In the excep tional case, the offspring evidently was sired by a male external to t he group. Analysis of similarity values supported the conclusion that matings by helpers or extra-group males are rare or non-existent. Our results indicate that in this species advantages gained by individuals remaining on their natal territories as helpers do not generally incl ude siring offspring.