| inadvertent social information in breeding site selection of natal dispersing birds. | several species use the number of young produced as public information (pi) to assess breeding site quality. pi is inaccessible for synchronously breeding birds because nests are empty by the time the young can collect this information. we investigate if location cues are the next best source of inadvertent social information (isi) used by young prospectors during breeding site choice. we experimentally deployed isi as decoys and song playbacks of breeding males in suitable and sub-optimal habit ... | 2006 | 16543178 |
| mercury in breeding and wintering nelson's sparrows (ammodramus nelsoni). | the objective of this study was to increase our understanding of hg exposure in birds with obligate ties to coastal salt marsh and inland wetland systems. many species filling such niches are of conservation concern because of reduced size and quality of vital habitats. we used nelson's sparrow (ammodramus nelsoni) as an indicator of regional mercury (hg) availability in its breeding and wintering salt marsh and wetland habitats. blood, breast feathers and the first primary feather were sampled ... | 2011 | 21082242 |
| mercury in nelson's sparrow subspecies at breeding sites. | mercury is a persistent, biomagnifying contaminant that can cause negative effects on ecosystems. marshes are often areas of relatively high mercury methylation and bioaccumulation. nelson's sparrows (ammodramus nelsoni) use marsh habitats year-round and have been documented to exhibit tissue mercury concentrations that exceed negative effects thresholds. we sought to further characterize the potential risk of nelson's sparrows to mercury exposure by sampling individuals from sites within the ra ... | 2012 | 22384194 |
| relationship between blood mercury levels and components of male song in nelson's sparrows (ammodramus nelsoni). | mercury (hg) adversely affects the health and behavior of exposed wildlife; however, behavioral effects remain largely unknown. changes in avian singing behavior may affect a male's fitness because song reveals male quality and thus influences female mate choice and male territory-holding ability. nelson's sparrows (ammodramus nelsoni) live exclusively on salt marshes and risk high levels of hg exposure and bioaccumulation. we recorded songs of male nelson's sparrows at two locations with differ ... | 2012 | 22945769 |
| characterization of mercury and its risk in nelson's, saltmarsh, and seaside sparrows. | nelson's, saltmarsh, and seaside sparrows (ammodramus nelsoni, a. caudacutus, and a. maritimus, respectively) depend on marsh and wetland habitats--ecosystems in which mercury (hg) bioavailability is notoriously high. the purpose of the present study was to address the potential impact of hg on these species using first primary and breast feathers as non-destructive biomonitoring tools. | 2012 | 22962614 |
| genotype-environment associations support a mosaic hybrid zone between two tidal marsh birds. | local environmental features can shape hybrid zone dynamics when hybrids are bounded by ecotones or when patchily distributed habitat types lead to a corresponding mosaic of genotypes. we investigated the role of marsh-level characteristics in shaping a hybrid zone between two recently diverged avian taxa - saltmarsh (ammodramus caudacutus) and nelson's (a. nelsoni) sparrows. these species occupy different niches where allopatric, with caudacutus restricted to coastal marshes and nelsoni found i ... | 2016 | 26811792 |
| differential introgression and the maintenance of species boundaries in an advanced generation avian hybrid zone. | evolutionary processes, including selection and differential fitness, shape the introgression of genetic material across a hybrid zone, resulting in the exchange of some genes but not others. differential introgression of molecular or phenotypic markers can thus provide insight into factors contributing to reproductive isolation. we characterized patterns of genetic variation across a hybrid zone between two tidal marsh birds, saltmarsh (ammodramus caudacutus) and nelson's (a. nelsoni) sparrows ... | 2016 | 27000833 |
| subspecies delineation amid phenotypic, geographic and genetic discordance in a songbird. | understanding the processes that drive divergence within and among species is a long-standing goal in evolutionary biology. traditional approaches to assessing differentiation rely on phenotypes to identify intra- and interspecific variation, but many species express subtle morphological gradients in which boundaries among forms are unclear. this intraspecific variation may be driven by differential adaptation to local conditions and may thereby reflect the evolutionary potential within a specie ... | 2017 | 28100017 |
| mercury levels of nelson's and saltmarsh sparrows at wintering grounds in virginia, usa. | nelson's and saltmarsh sparrows (ammodramus nelsoni and a. caudacutus) have recently been recognized as separate species, and because of their limited distributions and the susceptibility of their wetland habitats to climate change, these two new species are of conservation concern. both species are known to bioaccumulate mercury at breeding sites in new england, usa where their ranges overlap, with the saltmarsh sparrow reported to have twice the concentration of blood total mercury. in this st ... | 2011 | 21698442 |
| mercury in non-breeding sparrows of north carolina salt marshes. | we captured nelson's, saltmarsh and seaside sparrows (ammodramus nelsoni, a. caudacutus and a. maritimus) at three salt marsh sites near wrightsville beach, north carolina during five non-breeding seasons (september through april, 2006-2011). we analyzed breast feather samples from all of these seasons and blood and first primary feather (p1) samples from three seasons (2008-2011) for mercury (hg). generalized linear models were used to test for the impact of species, season, site and month on b ... | 2012 | 21947667 |