Fluctuating populations of house wrens and Bewick's wrens in foothills of the Western Sierra Nevada of California

Article Abstract:

The numbers of Bewick's Wrens have been declining throughout the eastern and midwestern US, possibly due to the expanding populations of House Wrens. However no direct cause and effect relation has been established. The null hypothesis that annual changes in numbers of Bewick's Wrens are unrelated to annual changes in numbers of House Wrens, has been tested using five years of spot-mapping data. The results provide no evidence of interspecific competition between House and Bewick's Wrens, and analysis of locations of song posts supports the null hypothesis of no difference between expected and observed counts of song posts. Food supply may explain a strong link between House Wren abundance and low temperatures in the winter.

Bird populations

Effect of egg covering and habitat on nest destruction by house wrens

Article Abstract:

House wrens are known to attack the nests and eggs of other cavity-nesting species but little research has been undertaken into the behaviors of target species that may allow them to escape or limit such attacks. A new study examines the effect of different egg concealment behaviors and nest habitat choice on the risk of nest destruction. The findings suggest that birds which cover their eggs prior to incubation may be less prone to egg destruction by house wrens. It is also shown that nest destruction by wrens is motivated by gaining nesting cavities.

Observations, Bird eggs, Bird nests, Nest building

Seasonal migration and genetic population structure in House Wrens

Article Abstract:

Research is presented concerning the lack of gene flow in isolated breeding pockets of sedentary birds such as the House Wrens. A comparison of the population structure of sedentary and migratory House Wrens is discussed.

Genetic aspects, Bird migration, Population genetics, Demographic surveys