Geography of Spring Landbird Migration Through Riparian Habitats in Southwestern North America

Migration stopover resources, particularly riparian habitats, are critically important to landbirds migrating across the arid southwestern region of North America. To explore the effects of species biogeography and habitat affinity on spring migration patterns, we synthesized existing bird abundance and capture data collected in riparian habitats of the borderlands region of the U.S. and Mexico. We determined the importance of geographic factors (longitude and latitude) in explaining variation in abundances and capture rates of 32 long-distance and three short-distance migrant species. Abundances and capture rates of 13 and 11 species, respectively, increased with increasing longitude, and four species\u27 abundance and capture rates decreased with increasing longitude. Riparian associates, but not nonriparian species, were more abundant in western sites. Their abundance patterns were only weakly influenced by species biogeography. In contrast, biogeography did influence abundance patterns of nonriparian birds, suggesting that they choose the shortest, most direct route between wintering and breeding areas. We hypothesize that riparian obligate birds may, to some degree, adjust their migration routes to maximize time spent in high-quality riparian zones, but they are able to find suitable habitat opportunistically when crossing more hostile landscapes. In contrast, nonriparian birds adhere more closely to a hierarchical model in which the migratory route is determined by biogeographic constraints. Conservation of riparian habitats is necessary to meet future habitat stopover requirements of many western Neotropical migrant birds. We advocate a coordinated research effort to further elucidate patterns of distribution and habitat use so that conservation activities can be focused effectively

Expression of NF-κB p50 in Tumor Stroma Limits the Control of Tumors by Radiation Therapy

Radiation therapy aims to kill cancer cells with a minimum of normal tissue toxicity. Dying cancer cells have been proposed to be a source of tumor antigens and may release endogenous immune adjuvants into the tumor environment. For these reasons, radiation therapy may be an effective modality to initiate new anti-tumor adaptive immune responses that can target residual disease and distant metastases. However, tumors engender an environment dominated by M2 differentiated tumor macrophages that support tumor invasion, metastases and escape from immune control. In this study, we demonstrate that following radiation therapy of tumors in mice, there is an influx of tumor macrophages that ultimately polarize towards immune suppression. We demonstrate using in vitro models that this polarization is mediated by transcriptional regulation by NFκB p50, and that in mice lacking NFκB p50, radiation therapy is more effective. We propose that despite the opportunity for increased antigen-specific adaptive immune responses, the intrinsic processes of repair following radiation therapy may limit the ability to control residual disease

Avian Conservation in the Prairie Pothole Region, Northern Great Plains: Understanding the Links between Climate, Ecosystem Processes, Wetland Management, and Bird Communities

Historically, the Prairie Pothole Region (PPR) of North America was characterized by myriad semi-permanent, seasonal, and temporary wetlands interspersed among rivers in a context of prairie uplands. These wetlands have supported millions of en route and breeding wetland-dependent birds. Today, expanses of the PPR landscape are dominated by intensive agriculture, and many of the remaining habitats have been impacted by altered water regimes, increasing sedimentation, and changes in plant communities. Climate change is likely to cause further alterations by shifting the seasonal availability and distribution of water and vegetation communities. Climate change will also affect the phenology (annual recurrence of phenomena) of vegetation green-up, seed production, and insect emergence. In concert, these changes could alter the capacity of PPR habitats to support waterbirds. Consequently, natural-resource managers and conservation planners in the PPR have an immediate need for effective tools that can evaluate the effects these changes would have on wetland-dependent bird communities. To that end, a team of U.S. Geological Survey (USGS) scientists and cooperators with expertise in the sciences of climate, hydrology, and ecology has convened to address the potential impacts of climate change on wetland-dependent bird species in the PPR. This team is developing a set of products, including: (1) a synthesis of current knowledge on the interrelationships of climate, wetlands condition, and bird communities; and (2) data on historical and future projections of climate (these projections will be formatted for use in standard mapping software). We will develop models to: (1) forecast effects and biological outcomes of climate change on water quality and quantity in wetlands and riverine ecosystems of the PPR; (2) elucidate relationships between climate, streamflow, water management, and wetland plants; and (3) understand and forecast bird responses to changing habitat conditions and to the timing of resource availability. The outcomes of this research will inform and assist managers and conservation professionals tasked with conserving populations of wetland-dependent birds

Geography of spring landbird migration through riparian habitats in southwestern North America. Condor

Abstract. Migration stopover resources, particularly riparian habitats, are critically important to landbirds migrating across the arid southwestern region of North America. To explore the effects of species biogeography and habitat affinity on spring migration patterns, we synthesized existing bird abundance and capture data collected in riparian habitats of the borderlands region of the U.S. and Mexico. We determined the importance of geographic factors (longitude and latitude) in explaining variation in abundances and capture rates of 32 longdistance and three short-distance migrant species. Abundances and capture rates of 13 and 11 species, respectively, increased with increasing longitude, and four species' abundance and capture rates decreased with increasing longitude. Riparian associates, but not nonriparian species, were more abundant in western sites. Their abundance patterns were only weakly influenced by species biogeography. In contrast, biogeography did influence abundance patterns of nonriparian birds, suggesting that they choose the shortest, most direct route between wintering and breeding areas. We hypothesize that riparian obligate birds may, to some degree, adjust their migration routes to maximize time spent in high-quality riparian zones, but they are able to find suitable habitat opportunistically when crossing more hostile landscapes. In contrast, nonriparian birds adhere more closely to a hierarchical model in which the migratory route is determined by biogeographic constraints. Conservation of riparian habitats is necessary to meet future habitat stopover requirements of many western Neotropical migrant birds. We advocate a coordinated research effort to further elucidate patterns of distribution and habitat use so that conservation activities can be focused effectively