The traits that predict the magnitude and spatial scale of forest bird responses to urbanization intensity

As humans continue moving to urban areas, there is a growing need to understand the effects of urban intensification on native wildlife populations. Forest species in remnant habitat are particularly vulnerable to urban intensification, but the mechanisms behind these effects are poorly understood. An understanding of how species traits, as proxies for mechanisms, mediate the effects of urban intensification on forest species can help fill this knowledge gap. Using a large point count dataset from the Second Pennsylvania Breeding Bird Atlas, we tested for the effects of species traits on the magnitude and spatial scale of the responses of 58 forest bird species to urbanization intensity in landscapes surrounding count locations. Average urbanization intensity effect size across species was -0.36 ± 0.49 (SE) and average scale of effect of urbanization intensity was 4.87 ± 5.95 km. Resident forest bird species that are granivorous or frugivorous, cavity-nesting, and have larger clutch sizes and more fledglings per clutch had more positive associations with increasing urbanization intensity in landscapes. In addition, the effect of urbanization intensity on forest birds manifested most strongly at larger spatial scales for granivorous, frugivorous, or omnivorous species that are cavity-nesting, have larger clutch sizes and longer wingspans, and flock in larger numbers. To our knowledge, the present study represents the first direct tests of the effects of species traits on both the magnitude and spatial scale of the effect of urbanization on forest birds, as well as the first evidence that migratory status, clutch size, wingspan, and fledglings per clutch are important determinants of the responses of forest birds to urbanization. We discuss the possible mechanisms underlying our results and their implications for forest bird conservation in urbanizing landscapes.

Fertility of turkey hens correlated with depth of insemination

In a two year comparison of shallow insemination (two cm.) and deep insemination (seven cm.) involving both Large White and Bronze hens shallow insemination was superior to deep insemination for Large White hens. Shallow insemination of Large White hens resulted in a longer duration-of-fertility and a higher total fertility (P less than 0.01) than deep insemination. The mean fertiltity in a 51 day duration-of-fertility trial during early production was 56.1% following shallow insemination and 43.1% following deep insemination. Late in the breeding season the mean fertility was 39.7% and 27.4% for shallow and deep insemination, respectively. The mean duration-of-fetility was 40.4 days after shallow insemination and 31.2 days after deep insemination. Shallow insemination was superior to deep insemination whether hens were inseminated at 14 days or 28 day intervals. Fertility following shallow insemination of Bronze hens was not different from fertility following deep insemination. In a duration-of-fertility trial of Bronze hens, the mean fertility was 37.3% for shallow insemination and 39.8% for deep insemination. The mean duration-of-fertility were 51.2 days after shallow insemination and 47.0 days after deep insemination.