Breeding Productivity, Post-Fledging Movements, and Description of the Immature Stage of House Wrens (Troglodytes Aedon)

Prior to the 2000 and 2001 breeding seasons, 150 nest boxes were erected throughout riparian habitat in Ellis County, Kansas, to study breeding productivity and the post-fledging stage of the House Wren (Troglodytes aedon). During that interval I documented 222 individual breeding attempts, 113 (51%) of which were successful. A total of 96 (43%) breeding attempts failed because of predation, which occurred more frequently during the second year, while 13 (6%) failed because of other reasons such as egg-pecking and exposure. Calculations using the Mayfield estimation indicated the probability an egg present at the start of incubation produced a fledgling was 75% in 2000 and 36% in 2001. I color-banded 786 individuals (94 females, 62 males, and 630 nestlings) to allow for identification at nests and to facilitate observations away from nests. A total of 17 individuals from the 2000 breeding season exhibited site fidelity in /2001, consisting of ten adult breeders (2 females and 8 males) and seven first-year breeders (3 females and 4 males). First-year breeders traveled greater distances from their natal nest (1291 ± 26.3m) than adult birds did between each year's breeding attempt (131 ± 1.4m). Radio transmitters were used to monitor movements of fledglings and allowed for behavioral observations during the immature stage. Observations of feeding by either parent were limited to the first four days post-fledge, and suggested that fledglings began to forage on their own four to five days post-fledge. Fledglings remained within 100m of their natal nest during the first 20 days after leaving the nest, whereas from 21-32 days post-fledge, the distances traveled ranged from 80-710 meters. Aggregations of immature individuals, which consisted of color-banded fledglings from several different broods, as well as many unbanded fledglings, also were observed during this interval. Fledgling age and distance moved from natal nests varied among individuals in the aggregations. Parents were observed to feed only fledglings from their brood, indicating parent-young recognition. Immature aggregations exhibit characteristics resembling a type of creche.