Sharp-tailed Sparrow Research Articles

Estimating detection for salt-marsh songbirds during winter using the double-pass rope-drag technique.

Bird species that are restricted to tidal marshes during one or all of their life stages are under increasing pressure from sea-level rise. To date, most of the research focused on this group has been conducted during the breeding season despite the fact that more than half of the annual cycle is spent on wintering grounds and the high likelihood that the winter period is the most critical time for adult survival. We used a double-pass rope-drag technique to estimate the winter abundance of sharp-tailed sparrows (Ammospiza nelson and A. caudacutus collectively), seaside sparrows (A. maritimus) and marsh wrens (Cistothorus palustris) within tidal marshes of Virginia along 102 60X250 m transects between January and March, 2014. We used the first pass to remove birds from the transect and the second pass was used to estimate detection probabilities. The technique was highly effective producing detection rates of 98% for sharp-tailed sparrows, 95% for seaside sparrows, and 91% for marsh wrens. We conducted three rounds of surveys and found that species-specific detection rates were comparable when we restricted our analyses to two survey rounds. Availability and abundance estimates deviated to a greater degree than detection rates when restricting data to that collected during only two rounds but confidence intervals overlapped for all three taxa, regardless of which two survey periods were used for the comparison. However, results were less precise when we restricted our analyses to two of three rounds with confidence intervals averaging 13%, 45%, and 14% larger for detection, availability, and abundance respectively. The double-pass rope-drag technique provides an effective, unbiased sampling technique to estimate winter songbird abundance in saltmarsh habitat provided that at least two rounds are used and increasing the number of survey rounds will result in more precise estimates.

Winter composition of Nelson’s Sparrow (Ammodramus nelsoni) and Saltmarsh Sparrow (Ammodramus caudacutus) mixed flocks in coastal Virginia

ABSTRACT We captured 1,055 Nelson’s (Ammodramus nelsoni) and Saltmarsh (Ammodramus caudacutus) sparrows during the winter season (2006–2014) within the outer Coastal Plain of Virginia to determine the composition of subspecies. Birds were captured using mist nets in 24 tidal salt marshes and identified to subspecies using a plumage-based, syntopic key. Contrary to previous assessments, both species of sharp-tailed sparrows were common. All five subspecies were present and appeared to form mixed flocks within patches. The north-Atlantic Saltmarsh Sparrow (A. c. caudacutus) was the most common form, accounting for 45% of all birds identified to subspecies. The three Nelson’s Sparrow forms including the “Acadian” Nelson’s Sparrow (A. n. subvirgatus), “James Bay” Nelson’s Sparrow (A. n. alter) and the “Nelson’s” Sparrow (A. n. nelsoni) were equally common and collectively accounted for 47% of the subspecies identified. The highly restricted, mid-Atlantic Saltmarsh Sparrow (A. c. diversus) was the least common...

Population abundance and trends of Saltmarsh (Ammodramus caudacutus) and Nelson’s (A. nelsoni) Sparrows: influence of sea levels and precipitation

Evidence of biological responses to climate change continues to grow. Long-term monitoring programs are critical in documenting these changes as well as identifying the primary stressors that may influence a species’ ability to adapt to changing climate. Eastern North American salt marshes support the greatest number of endemic salt marsh vertebrates globally, two of which are sympatric from southern Maine to northern Massachusetts, USA. Saltmarsh Sparrows (Ammodramus caudacutus), listed ‘vulnerable’ by the International Union for Conservation of Nature (IUCN), have a restricted global breeding range that occurs in salt marshes from Maine to Virginia, USA. Nelson’s Sparrows (Ammodramus nelsoni) breed in salt marshes from Massachusetts north to the Canadian Maritime Provinces and west to the prairie pothole regions of central Canada. These taxa hybridize in sympatry which may affect how these taxa respond to changing habitat quality and availability caused by climate change. We present the first estimates of the effects of sea level rise, breeding season precipitation, and salt marsh patch size on the abundance and population trends for three groups: (1) Saltmarsh Sparrows, (2) Nelson’s Sparrows, and (3) all Sharp-tailed Sparrows [the combined population of both species including hybrids]. We used 14 years of population monitoring data (2000–2013) from nine saltmarshes within the Rachel Carson National Wildlife Refuge, Maine, USA. We detected a declining trend for Saltmarsh Sparrow (i.e., significant decline, but not significantly more than 5 % per year), stable trends for Nelson’s Sparrows and for all Sharp-tailed Sparrows (i.e., no significant increase or decrease over the time period). Abundances for the three sparrow groups varied among years and marsh units. Drier years with relatively low mean sea levels had the greatest abundances. Breeding season precipitation negatively influenced population trends for Saltmarsh and Nelson’s Sparrows and mean sea level had a negative effect on Saltmarsh Sparrow population trends. Our results indicate that Saltmarsh Sparrow, the species most specialized to salt marshes, has declined which may be indicative of broader, regional patterns. The negative relationships of mean sea level and precipitation with Saltmarsh Sparrow population trends suggest that the negative effects of increasing nest flooding may be having demographic-level effects on this local population. Analyses of other salt marsh bird long-term monitoring programs are warranted to determine if this pattern is consistent in other portions of the Saltmarsh Sparrow range.

Incorporating Social Information to Improve the Precision of Models of Avian Habitat Use

Abstract. Correlations between habitat measures and animal distributions are not always applicable outside the study area that generated them. In such cases, the particularities of these correlations likely arise because only use of the local habitat has been quantified, rather than actual habitat selection, as the distribution models do not account for the behavior of animals in choice. The addition of covariates accounting for selection strategies could improve the precision and accuracy of correlative models of habitat use, but this conjecture has received little empirical attention. To evaluate this possibility, we re-assess previously developed habitat-use models for abundance of males of three grassland birds by explicitly including two measures of selection behavior: the “propensity to aggregate” and “propensity to use social information.” Habitat-use models for Nelson's Sharp-tailed Sparrow (Ammodramus nelsoni) were not improved by either behavioral variable. However, models for two other species,...

EGG AND CHICK FATES DURING TIDAL FLOODING OF SALTMARSH SHARP-TAILED SPARROW NESTS

Abstract We determined nest attendance patterns of Saltmarsh Sharp-tailed Sparrows (Ammodramus caudacutus) in Connecticut using temperature data-loggers. In this species, only females incubate and feed the young. Females maintained a stable thermal environment in their nests during incubation by modifying their attendance behavior in relation to ambient temperature; during cooler conditions, females made shorter, but more frequent, trips away from their nests to feed. Once eggs hatched, average nest temperature increased significantly. The data-loggers also recorded information on rare and unpredictable events, such as nest flooding, depredation, and fledging. Eggs and nestlings apparently tolerated nest inundation for periods averaging more than 90 min. Nestlings fledged from their nests soon after sunset on the flooding tide. Detailed insight into nest attendance behavior and the circumstances surrounding rare events such as flooding are especially important for this species of high conservation concern...

HOW WELL CAN WE MODEL NUMBERS AND PRODUCTIVITY OF SALTMARSH SHARP-TAILED SPARROWS (AMMODRAMUS CAUDACUTUS) USING HABITAT FEATURES?

Abstract Habitat models are often used to describe species distributions, but they need to be tested to evaluate their predictive performance. We investigated the importance of model evaluation in a study of habitat selection by Saltmarsh Sharp-tailed Sparrows (Ammodramus caudacutus), a species of conservation concern in eastern North America. We estimated the number of birds, nests, and fledglings produced in thirty 1-ha study plots spread across multiple marshes and used an information-theoretic approach to select among explanatory habitat models. Model performance was evaluated using both the original data set and data from another 30 plots from the same set of marshes. Our models indicate that both female and male Saltmarsh Sharp-tailed Sparrows increase in abundance as one moves away from the marsh's upland edge and in areas where there is deep thatch and uniform vegetation height. In contrast to the results for adult birds, number of nests and production of fledglings were positively associated with...

Novel microsatellite markers for the saltmarsh sharp‐tailed sparrow, Ammodramus caudacutus (Aves: Passeriformes)

We have developed eight high-quality microsatellite DNA loci for the saltmarsh sharp-tailed sparrow and one additional locus with evidence of null alleles. In a sample of 250-350 individuals, the average number of alleles per locus was 14.7 and average observed heterozygosity was 0.80. These loci were tested in three additional species of emberizid sparrows, indicating that more than half of the loci could be useful in other sparrows.

Corrigendum

Molecular Ecology ResourcesVolume 8, Issue 1 p. 233-233 Free Access Corrigendum This article corrects the following: Novel microsatellite markers for the saltmarsh sharp-tailed sparrow, Ammodramus caudacutus (Aves: Passeriformes) CHRISTOPHER E. HILL, SCOTT TOMKO, CRIS HAGEN, NANCY A. SCHABLE, TRAVIS C. GLENN, Volume 8Issue 1Molecular Ecology Resources pages: 113-115 First Published online: June 28, 2008 First published: 28 June 2008 https://doi.org/10.1111/j.1471-8286.2007.02018.xAboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat The authors (Hill et al.) of the study ‘Novel microsatellite markers for the saltmarsh sharp-tailed sparrow, Ammodramus caudacutus (Aves: Passeriformes)’ have alerted us to an error in Table 1 of their work. Table 1. Characteristics of nine new microsatellite loci from the saltmarsh sparrow, Ammodramus caucadutus. Size ranges, number of alleles (NA), observed (HO) and expected (HE) heterozygosity from 250–350 individuals from Connecticut. Clone column lists size (in bp) of PCR product in each clone Locus GenBank Accession no. Primer sequences (5′–3′) 5′ fluorescent tag as indicated Repeat motif Clone (bp) Range (bp) N A H O H E Amplification conditions ([MgCl2], AT, no. of cycles) Aca01EF447093 6FAM-AGCCCACTAATGGGTTTTCCTGAGTGTTCAAAGTTGCCAGA (TCTA)14(TCA)2-TCTATCA(TCTA)13 229 165–229 15 0.867 0.877 2.5 mm, 56C, 32 Aca04†EF447094 6FAM-CAATGGTGACTGCAATCCTGCCTCAGCCATTTCTGTTGTCT (TCTA)11(TC)3TATCC-(TCTA)13 211 157–291 32 0.858 0.902 2.5 mm, 56C, 32 Aca05EF447095 HEX-CCTGCTAGGCTGCATCTTCTGAGTGTCATCACATTTGTACTTTGG (TGTC)2(TATG)7(TATC)14 203 193–239 12 0.823 0.860 2.5 mm, 56C, 32 Aca08EF447096 6FAM-TAGCCACAAGCAAGACCTGACTGTGACAGGAAGGGCAGTT (AC)18 175 165–185 10 0.767 0.790 3.0 mm, 56C, 32 Aca10EF447097 NED-GACCGGGATTTCCATTCATATGCTATTAGGTCTTTTCATTGTCC (TATC)(TGTC)(TATC)11 190 158–194 10 0.795 0.775 2.5 mm, 56C, 32 Aca11EF447098 NED-AGCTTCCCATACCTGAATGCGAAAGGCATGAGTTTACAGTGG (AGAT)12 142 130–166 14 0.789 0.832* 2.5 mm, 56C, 32 Aca12‡ EF447099 HEX-GCTTGTTTCCTGTTCCCAAAAATCGGATCCATAGACTTCAAA (GATA)9G(GATA)5(GACA)2- (GACG)(GATA)2GATG 243 213–257 20 0.785 0.902 2.5 mm, 56C, 32 Aca17EF447100 NED-GGAGCATGTGACAATGGAGTTCTGTGCTGTTCCAAGCAGA (TCTA)13(TC)9 242 234–258 8 0.752 0.771 2.5 mm, 50C, 40 Aca21§EF447101 NED-CCCTCTCCCTGGCTACTCTTCTGGTGCTTCTGGCTCAGT (ATCT)14(TC)8 247 223–259 11 0.595 0.773* 2.5 mm, 50C, 40 * Significant departure from HWE. † Although a tetranucleotide repeat with typical 4 bp stutter, Aca04 has alleles spaced every 2 bp for much of its range. ‡ Although a tetranucleotide repeat, Aca12 has two series of alleles differing by a single bp, so that spacing between allelic sizes in bp goes 3, 1, 3, 1 etc. § Aca21 has known, fairly common null alleles, with frequency estimated at 0.125. The corrected table is as follows: Reference Hill CE, Tomko S, Hagen C, Schable NA, Glenn TC (2007) Novel microsatellite markers for the saltmarsh sharp-tailed sparrow, Ammodramus Caudacutus (Aves: Passeriformes). Molecular Ecology Notes, doi: 10.1111/j.1471-8286.2007.01885.x Volume8, Issue1January 2008Pages 233-233 ReferencesRelatedInformation

WINTERING DISTRIBUTIONS AND MIGRATION OF SALTMARSH AND NELSON'S SHARP-TAILED SPARROWS

We delineate the winter distributions of the five subspecies of Saltmarsh Sharp-tailed (Ammodramus caudacutus) and Nelson's Sharp-tailed (A. nelsoni) sparrows, and comment on patterns of migration. The two subspecies of A. caudacutus (A. c. caudacutus, A. c. diversus) have similar core winter ranges that extend along the Atlantic coast from North Carolina to northeastern Florida. They also occupy two isolated areas within peninsular Florida in Everglades National Park and on the northwest Gulf coast. Migration in A. caudacutus is mainly confined to the coast. The subspecies of A. nelsoni (A. n. nelsoni, A. n. alterus, A. n. subvirgatus) occupy different but overlapping winter ranges. A. n. nelsoni is the most widespread, occurring from North Carolina to Texas. Some birds migrate along the Atlantic coast southwards in fall, and others follow interior routes through the Mississippi River watershed in both fall and spring. We suggest A. n. nelsoni wintering along the Atlantic coast in spring fly directly inland towards their northern breeding areas. Some birds in fall also approach the southeastern coastline directly across the Appalachian Mountains. A. n. alterus mainly winters along the southeastern Atlantic coast to Florida, and in fewer numbers along the Gulf coast at least to Louisiana. Some A. n. alterus may migrate to the Gulf coast directly via inland routes west of the Appalachian Mountains. A. n. subvirgatus has the most limited wintering distribution, from South Carolina to northeast Florida, and is strictly a coastal migrant south of New England. Limited wintering ranges and narrow winter habitat requirements place continental populations of sharp-tailed sparrows at risk.

Interspecific Interactions between Marsh-dwelling Ammodramus Sparrows at a Migration Stopover

Abstract The social behaviors of Le Conte's (Ammodramus leconteii) and Nelson's Sharp-tailed (A. nelsoni) sparrows are poorly documented, as are their interactions with one another, even in the prairie marshes they share during the breeding season. We report the regular coincident presence and similar habitat associations of these species at a fall migration stopover, the Baker University Wetlands, near Lawrence, Kansas, over an 11-year period, and describe social behaviors (several previously unrecorded) at the site, including an aggressive interspecific encounter.

Testing the function of the domed nests of Saltmarsh Sharp-tailed Sparrows

Saltmarsh Sharp-tailed Sparrows (Ammodramus caudacutus) build ground nests, often with a closely-woven dome, in marshes that frequently flood during high tides. To test the hypothesis that domed nests help reduce the loss of eggs and chicks due to flooding or predation, we examined the characteristics and fate of 102 nests at sites along the coast of Connecticut. To test whether nest structure was tailored to suit microhabitat conditions, we also measured vegetation characteristics around nests. Finally, we conducted artificial nest-flooding experiments to determine whether removal of domes reduced egg retention during flooding. We found no significant effects of nest structure on breeding success or failure, and few significant correlations between nest structure and microhabitat. The height of nests above the ground, however, increased with vegetation height, supporting the hypothesis that nest construction is influenced by flooding, but not supporting the hypothesis that predation risk is important. Dome removal experiments showed that domes have a highly significant effect on the retention of eggs during flooding, suggesting that domes help eggs survive the regular tidal flooding of marshes. SINOPSIS. Poniendo a pruebas la funci´ on del domo de los nidos de Ammodramus caudac-

Flood Tides Affect Breeding Ecology of Two Sympatric Sharp-Tailed Sparrows

AbstractBreeding synchrony with the lunar cycle has been reported for many marine organisms but is essentially unknown for birds. Most organisms shown to breed synchronously with the lunar cycle provide no parental care to young, and such explosive breeding assemblages are usually promiscuous. Saltmarsh Sharp-tailed Sparrows (Ammodramus caudacutus caudacutus) nest exclusively on salt marshes and are subjected to predictable, catastrophic flooding caused during flood tides every 28 days. Here, we show that Saltmarsh Sharp-tailed Sparrow males were nonterritorial and promiscuous and provided no parental care to young. Breeding behaviors of both sexes were synchronized with the lunar cycle. By contrast, males of a sympatric sister species, Nelson's Sharp-tailed Sparrow (A. nelsoni subvirgatus), consistently mate-guarded females, and breeding was not synchronized with the lunar cycle, yielding 21% lower reproductive success compared with Saltmarsh Sharp-tailed Sparrows. Saltmarsh and Nelson's sharp-tailed sparrows renested 2.9 ± 0.6 (SE) days and 10.3 ± 1.7 days after nest flooding, respectively. Patterns of vicariance between Nelson's and Saltmarsh sharp-tailed sparrows may explain the differences in social behavior and nesting ecology. Ancestral sharp-tailed sparrows diverged from Seaside Sparrows (A. maritimus) in tidal wetlands, and Nelson's Sharp-tailed Sparrows then diverged from Saltmarsh Sharp-tailed Sparrows in nontidal freshwater wetlands of interior North America. Nelson's Sharp-tailed Sparrows' range recently expanded into coastal salt marshes, where Saltmarsh Sharp-tailed Sparrows are better adapted to tidally influenced inundations. Adaptation to tidal flooding partially explains the evolution of the unique Saltmarsh Sharp-tailed Sparrow mating system.Las Inundaciones Mareales Afectan la Ecología Reproductiva de Dos Especies Simpátricas de Ammodramus

Differential habitat use by Acadian Nelson's sharp-tailed sparrows: implications for regional conservation

ABSTRACT Nelson's Sharp-tailed Sparrows (Ammodramus nelsoni) that breed along the Atlantic coast of North America (Acadian subspecies subvirgatus) are considered saltmarsh specialists. However, these sparrows occasionally use upland habitats, such as hayfields. To evaluate the importance of hayfields as breeding habitat, we studied populations of A. n. subvirgatus in saltmarsh and hayfields in Nova Scotia, Canada, in 2004 and 2005. We monitored relative abundance and breeding phenology at 64 point-count stations (48 in hayfields and 16 in saltmarsh) and used an ordinal (0–5) observational index to quantify reproductive activity. A. n. subvirgatus showed more evidence of reproductive activity in saltmarsh (44% of point-count stations) than hayfields (28%; P= 0.07). However, there was no difference in either mean reproductive activity (saltmarsh = 0.83, hayfields = 0.53; P= 0.69) or mean relative abundance (saltmarsh = 0.27, hayfields = 0.26; P= 0.93). Although A. n. subvirgatus apparently breeds primarily in saltmarsh, hayfields appear to be an alternative breeding habitat. Use of hayfield habitat by A. n. subvirgtus, however, seems to vary between southern Maine and eastern Canada, suggesting that management plans will require approaches uniquely tailored to specific regions. La subespecie Acadian del Gorrión de Nelson (Ammodramus nelsoni subvirgatus), que se reproduce a lo largo de la costa del Atlántico en Norte América, es considerada un especialista de marjales. Sin embargo, estos gorriones han sido observados (ocasionalmente) usar habitats de tierras altas como sembrados de heno. Para evaluar la importancia de las siembras de heno como habitat reproductivo del ave, estudiamos poblaciones de la subespecie subvirgatus del Gorrion de Nelson que se reprodujeron en marjales y en campos de heno, en Nova Scotia, Canada durante el 2004 y el 2005. Monitoreamos la abundancia relativa y la fenología reproductiva en 64 estaciones de punto (48 en campos de heno y 16 en marjales) y utilizamos un índice de observación (0-5) para cuantificar la actividad reproductiva. Se encontró evidencia de mayor actividad reproductiva en los marjales (44% de las estaciones) que en los campos de heno (28%; P= 0.07). Sin embargo, no se encontró diferencia en la actividad promedio reproductiva (marjales = 0.83, campos de heno = 0.53; P= 0.93). Aunque el ave anida principalmente en marjales, los campos de heno parecen ser un buen habitat alterno para la reproducción. El uso de campos de heno, parece variar entre localidades como el sur de Maine y el este de Canada, lo que sugiere que los planes de manejo tienen que amoldarse con especificidad a cada región.

FLOOD TIDES AFFECT BREEDING ECOLOGY OF TWO SYMPATRIC SHARP-TAILED SPARROWS

Breeding synchrony with the lunar cycle has been reported for many marine organisms but is essentially unknown for birds. Most organisms shown to breed synchronously with the lunar cycle provide no parental care to young, and such explosive breeding assemblages are usually promiscuous. Saltmarsh Sharp-tailed Sparrows (Ammodramus caudacutus caudacutus) nest exclusively on salt marshes and are subjected to predictable, catastrophic flooding caused during flood tides every 28 days. Here, we show that Saltmarsh Sharp-tailed Sparrow males were nonterritorial and promiscuous and provided no parental care to young. Breeding behaviors of both sexes were synchronized with the lunar cycle. By contrast, males of a sympatric sister species, Nelson's Sharp-tailed Sparrow (A. nelsoni subvirgatus), consistently mate-guarded females, and breeding was not synchronized with the lunar cycle, yielding 21% lower reproductive success compared with Saltmarsh Sharp-tailed Sparrows. Saltmarsh and Nelson's sharp-tailed sparrows renested 2.9 ± 0.6 (SE) days and 10.3 ± 1.7 days after nest flooding, respectively. Patterns of vicariance between Nelson's and Saltmarsh sharp-tailed sparrows may explain the differences in social behavior and nesting ecology. Ancestral sharp-tailed sparrows diverged from Seaside Sparrows (A. maritimus) in tidal wetlands, and Nelson's Sharp-tailed Sparrows then diverged from Saltmarsh Sharp-tailed Sparrows in nontidal freshwater wetlands of interior North America. Nelson's Sharp-tailed Sparrows' range recently expanded into coastal salt marshes, where Saltmarsh Sharp-tailed Sparrows are better adapted to tidally influenced inundations. Adaptation to tidal flooding partially explains the evolution of the unique Saltmarsh Sharp-tailed Sparrow mating system. Las Inundaciones Mareales Afectan la Ecología Reproductiva de Dos Especies Simpátricas de Ammodramus

Nestling diets of coexisting salt marsh sparrows: Opportunism in a food-rich environment

The saltmarsh sharp-tailed sparrow (Ammodramus caudacutus) and the morphologically similar seaside sparrow (Ammodramus maritimus) occur together in Atlantic coast salt marshes. Over 2 yr we examined food exploitation patterns to gain an understanding of how these species coexist and to characterize the trophic conditions that allow the maintenance of different mating systems within the same habitat. In the promiscuous saltmarsh sharp-tailed sparrow, only females feed the young, while the young of the socially monogramous seaside sparrow are fed by both parents. To determine dietary patterns, we used a nonlethal method (throat constriction) to obtain food samples from nestlings. Resource states were determined by sweep-netting the vegetation and by taking cores from the marsh surface. Based on volume, the same 4 prey groups (flies, amphipods, grasshoppers, moths) composed > 80% of each species diet. The main food of both sparrows was adult and juvenile (larval and pupal) soldier flies (Stratiomyidae:Odontomyia microstomata). Measures of dietary overlap, based on resource states, indicated that nestling diets did not differ between species on a seasonal basis or over 2-wk intervals. As the season progressed, each species tracked in parallel changes in resource abundance. Diets did not diverge from what was expected if food was exploited randomly; diets frequently overlapped significantly more than expected. Interspecific resource-use patterns were congruent over 2 yr. Based on the results of this study, and on an evaluation of hypotheses based on life history information from previously published work, we conclude that food usually is not limiting for these sparrows and that resource abundance has fostered behavioral and dietary opportunism.

Mercury in Sharp-Tailed Sparrows Breeding in Coastal Wetlands

Current levels of anthropogenic mercury (Hg) in the environment can cause harm to humans and wildlife. Well-documented negative effects on birds are described, but there is presently limited information for passerine exposure to mercury. Some investigations have used insect-eating birds as potential bioindicators of mercury exposure. However, our understanding of methlymercury (MeHg) availability to birds in coastal wetlands, tidal systems that may be especially conducive to Hg methylation, remains poor. Two species of sharp-tailed sparrow breed in coastal wetlands in eastern North America and are suitable candidate indicators for contaminants in these habitats. We measured blood Hg from breeding Saltmarsh (Ammodramus caudacutus) and Nelson’s (Ammodramus nelsoni) sharp-tailed sparrows in five Maine salt marshes to determine if these species could be used to assess the extent of MeHg availability in salt marshes. Blood Hg for both species differed among the five marshes with concordance between species and...

Nelson's Sharp-tailed Sparrow Nest Parasitized by Brown-headed Cowbird

On 22 July 2004, we found a Nelson's Sharp-tailed Sparrow (Ammodramus nelsoni) nest in Sheridan County, Montana, containing a single Brown-headed Cowbird (Molothrus ater) nestling that was about to fledge. A punctured sharp-tailed sparrow egg was found below the nest. This is the second definitive report of cowbird brood parasitism of a Nelson's Sharp-tailed Sparrow nest and the first indicating successful rearing of a cowbird by this host species. The impact of cowbird parasitism on nesting success of Nelson's Sharp-tailed Sparrow has not been studied, but our record indicates that nest failure (i.e., producing no host young) may be an outcome for some nests of this species.

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 habitats during pre- and post-breeding periods, and monitored territory establishment during the subsequent breeding season for a social, bobolink (Dolichonyx oryzivorus), and a more solitary species, Nelson's sharp-tailed sparrow (Ammodramus nelsoni). The sparrows did not respond to treatments, but bobolinks responded strongly to post-breeding location cues, irrespective of habitat quality. The following year, 17/20 sub-optimal plots to which bobolink males were recruited were defended for at least two weeks, indicating that song heard the previous year could exert a "carry-over attraction" effect on conspecifics the following year. Sixteen recruited males were natal dispersers, as expected when animals have little opportunity to directly sample their natal habitat quality. We suggest that differences in breeding synchronicity may induce an equivalent clinal distribution of ISI use.

Nest Site Selection and Nesting Success in Saltmarsh Breeding Sparrows: The Importance of Nest Habitat, Timing, and Study Site Differences

Abstract We examined nest-site selection and nesting success in Saltmarsh Sharp-tailed (Ammodramus caudacutus) and Seaside Sparrows (A. maritimus), at seven sites in Connecticut. We found 160 Saltmarsh Sharp-tailed Sparrow nests and 23 Seaside Sparrow nests, and compared characteristics of their locations to each other and to random locations. We tracked success of all nests, quantified nest productivity and causes of nest losses, and tested for habitat differences between successful and unsuccessful nests. Saltmarsh Sharp-tailed Sparrows nested in higher than average locations, where the vegetation was taller and more dense than at random locations, where there was a deep layer of thatch, and where saltmeadow cordgrass (Spartina patens) dominated the vegetation. There was little evidence that habitat characteristics influenced the success of nesting birds, but the timing of nest initiation relative to spring tides was important. Seaside Sparrow nests occurred in even taller vegetation, that was more sparse than average and dominated by the tall form of smooth cordgrass (S. alterniflora). Habitat influenced the success of Seaside Sparrow nests, but timing did not; on average, successful nests occurred in taller vegetation. Model comparisons suggest that vegetation structure influences site selection more than species composition or inherent differences among marshes. Overall, our results indicate that nest flooding is a major threat to successful reproduction in both species, but they have different strategies to avoid flooding. Saltmarsh Sharp-tailed Sparrows time their reproduction to avoid especially high tides, while Seaside Sparrows avoid flooding spatially by nesting in tall vegetation.

Concordance Between Morphological and Molecular Markers in Assessing Hybridization Between Sharp-Tailed Sparrows in New England

AbstractHybridization is pivotal in framing ideas about species concepts and has the potential to produce novel genotypes that may serve as starting points for new evolutionary trajectories. Presently, Nelson’s Sharp-tailed Sparrows (Ammodramus nelsoni subvirgatus) and Saltmarsh Sharp-tailed Sparrows (A. caudacutus caudacutus) are in contact in salt marshes of Maine, New Hampshire, and northern Massachusetts. These two species hybridize, but the extent and direction of introgression has not been determined. We assessed morphological and genetic variation of 123 sharp-tailed sparrows from 5 salt marshes in New England. We used six morphological variables, including a plumage-scoring index, and five mic-rosatellite primers to assess the extent of introgression and to determine whether there was concordance between phenotypic and genotypic variation. We identified apparent hybrids and each of the two sharp-tailed sparrow species using a plumagescoring index. In general, we found that hybrids were more similar morphologically and genetically to Saltmarsh Sharp-tailed Sparrows. The alleles of hybrids were 62% Saltmarsh and 38% Nelson’s Sharp-tailed Sparrows, supporting the asymmetrical hybridization hypothesis.Concordancia entre Marcadores Morfológicos y Moleculares al Evaluar la Hibridación entre Ammodramus nelsoni subvirgatus y A. caudacutus caudacutus en Nueva Inglaterra