An Estimate of Avian Mortality at Communication Towers in the United States and Canada

Avian mortality at communication towers in the continental United States and Canada is an issue of pressing conservation concern. Previous estimates of this mortality have been based on limited data and have not included Canada. We compiled a database of communication towers in the continental United States and Canada and estimated avian mortality by tower with a regression relating avian mortality to tower height. This equation was derived from 38 tower studies for which mortality data were available and corrected for sampling effort, search efficiency, and scavenging where appropriate. Although most studies document mortality at guyed towers with steady-burning lights, we accounted for lower mortality at towers without guy wires or steady-burning lights by adjusting estimates based on published studies. The resulting estimate of mortality at towers is 6.8 million birds per year in the United States and Canada. Bootstrapped subsampling indicated that the regression was robust to the choice of studies included and a comparison of multiple regression models showed that incorporating sampling, scavenging, and search efficiency adjustments improved model fit. Estimating total avian mortality is only a first step in developing an assessment of the biological significance of mortality at communication towers for individual species or groups of species. Nevertheless, our estimate can be used to evaluate this source of mortality, develop subsequent per-species mortality estimates, and motivate policy action

Lymphotoxin detected in the blister fluid of bullous pemphigoid patients

The role of lymphocytes in the pathogenesis of bullous pemphigoid was examined by assaying the blister fluid obtained from bullous pemphigoid patients for the presence of the lymphokine, lymphotoxin. Blister fluids from six bullous pemphigoid were assayed on L-929 target cells for the presence of cytolytic molecules in the standard lymphotoxin assay. Three of six blister fluids obtained from bullous pemphigoid patients and one linear IgA bullous dermatosis patient contained significant levels of cytolytic activity. Control blister fluids from suction blisters, herpes, pemphigus, and toxic epidermal necrolysis patients did not contain cytolytic activity. Serum from five bullous pemphigoid patients also had no cytolytic activity. Neutralization studies using rabbit anti-alpha-lymphotoxin demonstrated that 54 to 88% of the cytolytic activity found in bullous pemphigoid blister fluid was due to alpha-lymphotoxin. These results indicate that lymphotoxin is locally released in the skin of bullous pemphigoid lesions and is detectable in blister fluids