When a nest containing eggs or young was located,
we used song playbacks to lure adults into mist nets
placed near the nest. Blood samples from adults and
nestlings were taken from the brachial artery (Wingfield
and Famer 1976) and a volume of lysis buffer
(TE-SDS) approximately equal to the volume of whole
blood was added. Predation was very high and all eggs
left in the nest initially in our 1993 season disappeared
within 2-3 days. This forced us to remove eggs from
nests (after catching and bleeding parents) and to incubate
them long enough so that sufficient DNA could
be obtained from the embryos. DMSO lysis buffer
(Seutin et al. 1991) was used to store these tissue samples.
Samples were transported on ice and stored at
-20°C.
Whole genomic DNA was isolated as in Fleischer
et al. (1994) and subjected to multilocus DNA fingerprinting
using the Jeffreys 33.15 and 33.6 probes (Jeffreys
et al. 1985) and standard methods (see Loew and
Fleischer 1996 for specific protocols).
Following the approach of Westneat (1990) the two
adults defending a nest were excluded from co-parentage
if an offspring’s profile contained three or more
fragments that could not be assigned to either putative
parent (non-attributable bands). Band sharing coefficients
(S of Lynch 1990) were calculated from a presence/
absence matrix of same-sized fragments for putative
related and unrelated individuals. To assess the
possibility that our data could not reveal EPFs, we substituted
the nearest putative unrelated adult for one parent
(the sham) and then counted the number of nonattributable
fragments and calculated S (Fleischer et al.
1994).