Plumage Variation, Plasma Steroids and Social Dominance in Male House Finches

In male House Finches (Carpodacusm exicanus), the extent and color of plumage varies depending on access to carotenoid pigments. Colorful males exhibit extensive red pigmentation, while less colorful (i.e., drab ) males exhibit carotenoid pigmentation over a smaller percentage of their plumage, pigmentation of a color besides red (e.g., yellow, gold, orange, or pink), or both. One explanation for maintenance of plumage variation is that it reliably reflects social status, allowing males to correctly assess their status in relation to others and avoid or minimize costly fights. Social relationships may also be related to endogenous factors, such as circulating levels of the hormones testosterone and corticosterone. High levels of testosterone may promote or facilitate increased aggression, and stress associated with receiving aggression from individuals of higher status may increase adrenal activity and secretion of corticosterone. We examined the relationship between plumage variability, steroid hormones, and social status in captive male House Finches during the non-breeding period in: (1) groups of males in which individuals varied by age, size, and plumage, and (2) pairs (dyads) of males matched for several measurable parameters except plumage. Testosterone and social status were not related in males competing in either groups or dyads, and levels of testosterone were routinely low. Corticosterone and status were not related in groups but, in dyads where subordinate individuals had little chance of escaping aggression from more dominant birds, subordinates exhibited significantly greater levels of corticosterone. Although drab males tended to achieve higher status than colorful males in both experiments, which is consistent with previous studies on free-living individuals, we could not reject the null hypothesis that plumage and status were unrelated. We conclude that dominance relationships among male House Finches during the non-breeding season may not be related to testosterone, but they are reflected by levels of corticosterone in some circumstances. Additionally, colorful plumage appears to be a poor predictor of high social status among male House Finches during the non-breeding season

Affordable, Real-Time, 3-D Avian Radar Networks For Centralized North American Bird Advisory Systems

Affordable avian radar systems are being developed for Natural Resource Management (NRM) and bird aircraft strike hazard (BASH) applications. Recently [I], the authors have reported on mobile avian radar system requirements and on a system design that is state-of-the-art. In the present paper, the system design of a single avian radar is expanded in scope to address 3-D avian radar networks. These are essential to fully realize an affordable yet high-performance North American bird advisory system. The proposed avian radar network design includes antenna, transceiver and signal processor designs for the avian radar sensor, network design, sensor integration, and system operation and control from an operations center

Wildlife in Airport Environments: Chapter 13 Radar Technology to Monitor Hazardous Birds at Airports

Bird strikes are the most common wildlife hazard to aviation safety (Dolbeer et ale 2000). Advances in habitat management at airports through the elimination and reduction of attractants, in combination with hazing and lethal control, have reduced avian hazards \u3c 152 m (500 feet) above ground level. Bird strikes above this altitude, however, are beyond the limits of traditional wildlife control techniques (Dolbeer 2011). Traditional avian survey methods used to monitor birds at airports (Cleary and Dolbeer 2005; Chapter 14) often fail to provide essential information on local bird activity and migration at higher altitudes, hazardous bird use of attractants near airports, and bird activity at night-information that could be provided by the strategic use of radar technology at and near airports (Dolbeer 2006)

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

Avian mortality at communication towers in the United States and Canada: which species, how many, and where?

Birds migrating to and from breeding grounds in the United States and Canada are killed by the millions in collisions with lighted towers and their guy wires. Avian mortality at towers is highly variable across species, and the importance to each population depends on its size and trajectory. Building on our previous estimate of avian mortality at communication towers, we calculated mortality by species and by regions. To do this, we constructed a database of mortality by species at towers from available records and calculated the mean proportion of each species killed at towers within aggregated Bird Conservation Regions. These proportions were combined with mortality estimates that we previously calculated for those regions. We then compared our estimated bird mortality rates to the estimated populations of these species in the United States and Canada. Neotropical migrants suffer the greatest mortality; 97.4% of birds killed are passerines, mostly warblers (Parulidae, 58.4%), vireos (Vireonidae, 13.4%), thrushes (Turdidae, 7.7%), and sparrows (Emberizidae, 5.8%). Thirteen birds of conservation concern in the United States or Canada suffer annual mortality of 1–9% of their estimated total population. Of these, estimated annual mortality is \u3e2% for Yellow Rail (Coturnicops noveboracensis), Swainson’s Warbler (Limnothlypis swainsonii), Pied-billed Grebe (Podilymbus podiceps), Bay-breasted Warbler (Setophaga castanea), Golden-winged Warbler (Vermivora chrysoptera), Worm-eating Warbler (Helmitheros vermivorum), Prairie Warbler (Setophaga discolor), and Ovenbird (Seiurus aurocapilla). Avian mortality from anthropogenic sources is almost always reported in the aggregate (‘‘number of birds killed’’), which cannot detect the species-level effects necessary to make conservation assessments. Our approach to per species estimates could be undertaken for other sources of chronic anthropogenic mortality

Wildlife in Airport Environments: Appendix, Index and Back Cover

In 1990, the 190 member nations of the International Civil Aviation Organization (ICAO) adopted, in Annex 14 to the Convention on Civil International Aviation, three recommended management practices regarding bird hazards to aviation. The recommended practices required that aviation authorities within each nation (1) assess the extent of the hazard posed by birds at and in the vicinity of airports certificated for passenger traffic, (2) take necessary action to decrease the number of birds, and (3) eliminate or prevent the establishment of any site in the vicinity of the airport that could attract birds and thereby present a danger to aviation. Because of the increasing threat posed by birds to aviation worldwide, member states voted to make these recommendations mandatory ICAO standards, effective November 2003. In 2009, ICAO expanded these standards to include terrestrial wildlife such as large mammals and reptiles that pose a risk at airports (ICAO 2009)

Map of communication towers in the United States and Canada by height class.

<p>Data acquired from Federal Communications Commission, Towermaps.com, and NAV CANADA.</p

Average search and scavenging rates taken from pesticide impact studies [42].

<p>Search and detection rates are based on daily averages weighted by the number of study plots. Search rates represent the proportion of carcasses found over the total number still present at the time of search. Scavenging rates represent daily measurements averaged over all plots without regard for the number of placed carcasses. Search rates are undoubtedly at the high end of that which is possible because the search procedures were optimized, always including trained lines of searchers spaced optimally for the habitat as well as the use of search dogs in some studies.</p

Distribution of residuals of tower height–mortality regression for 38 towers in the United States as adjusted for sampling effort, search efficiency, and scavenging.

<p>Contour lines indicate regions above and below the regression line. Although exhibiting a geographically variable pattern, the residuals are not significantly spatially autocorrelated.</p

Estimated annual avian mortality from communication towers by Bird Conservation Region.

<p>High mortality estimates in Peninsular Florida and Southeastern Coastal Plain reflect the more numerous and taller communication towers in these regions.</p