10 research outputs found
Cliff Roosting by Migrant Semipalmated Sandpipers, Calidris pusilla, at Farrier's Cove, Shepody Bay, New Brunswick
An observation of Semipalmated Sandpipers roosting on a cliff face in Shepody Bay, New Brunswick, suggests changes from âtraditionalâ roosting sites. Sandpipers may be altering their roosting patterns due to pressures from avian predators such as the recent, and successful, re-introduction of the Peregrine Falcon
Long-Term Continental Changes in Wing Length, but Not Bill Length, of a Long-Distance Migratory Shorebird
We compiled a >50âyear record of morphometrics for semipalmated sandpipers (Calidris pusilla), a shorebird species with a Nearctic breeding distribution and intercontinental migration to South America. Our data included >57,000 individuals captured 1972â2015 at five breeding locations and three major stopover sites, plus 139 museum specimens collected in earlier decades. Wing length increased by ca. 1.5 mm (>1%) prior to 1980, followed by a decrease of 3.85 mm (nearly 4%) over the subsequent 35 years. This can account for previously reported changes in metrics at a migratory stopover site from 1985 to 2006. Wing length decreased at a rate of 1,098 darwins, or 0.176 haldanes, within the ranges of other field studies of phenotypic change. Bill length, in contrast, showed no consistent change over the full period of our study. Decreased body size as a universal response of animal populations to climate warming, and several other potential mechanisms, are unable to account for the increasing and decreasing wing length pattern observed. We propose that the postâWWII nearâextirpation of falcon populations and their postâ1973 recovery driven by the widespread use and subsequent limitation on DDT in North America selected initially for greater flight efficiency and latterly for greater agility. This predation danger hypothesis accounts for many features of the morphometric data and deserves further investigation in this and other species
The Migration of Shorebirds in the Bay of Fundy
Volume: 99Start Page: 540End Page: 57
Deletion of the hypoxia-response element in the vascular endothelial growth factor promoter causes motor neuron degeneration
Hypoxia stimulates angiogenesis through the binding of hypoxia-inducible factors to the hypoxia-response element in the vascular endothelial growth factor (Vegf) promotor. Here, we report that deletion of the hypoxia-response element in the Vegf promotor reduced hypoxic Vegf expression in the spinal cord and caused adult-onset progressive motor neuron degeneration, reminiscent of amyotrophic lateral sclerosis, The neurodegeneration seemed to be due to reduced neural vascular perfusion. In addition. Vegf(165) promoted survival of motor neurons during hypoxia through binding to Vegf receptor 2 and neuropilin 1. Acute ischemia is known to cause nonselective neuronal death. Our results indicate that chronic vascular insufficiency and, possibly, insufficient Vegf-dependent neuroprotection lead to the select degeneration of motor neurons