Vermivora Chrysoptera Research Articles

Reciprocal Introgression Between Golden-Winged Warblers (Vermivora Chrysoptera) and Blue-Winged Warblers (V. Pinus) in Eastern North America

Abstract Golden-winged Warblers (Vermivora chrysoptera) and Blue-winged Warblers (V. pinus) are small, brightly colored Neotropical migrant birds that breed in eastern North America. Wherever the two species occur together, they hybridize to a limited degree, producing distinctive hybrid phenotypes. In recent decades, chrysoptera has experienced dramatic population declines across much of its range. Those declines have often been correlated with establishment and increase of pinus in the same areas, but it remains uncertain what, if any, role pinus has played in driving the decline of chrysoptera. In a first attempt at molecular genetic analysis of chrysoptera-pinus population dynamics, Gill (1997) reported cryptic, completely asymmetric, and possibly very rapid introgression of pinus mitochondrial DNA (mtDNA) into chrysoptera, causing what he termed “local cytonuclear extinction” of chrysoptera. As Gill (1997) noted, however, those results were based on relatively small samples from a single area in Pennsylvania. To begin to investigate the generality of Gill’s findings and to establish a baseline for long-term genetic and ecological studies, we intensively sampled one new study area (in southern West Virginia) and also sampled more broadly across two other areas (in Michigan and Ohio) that have experienced pinus invasions and chrysoptera declines. In southern West Virginia, introgression of mtDNA appeared to be roughly symmetrical: 15% (11 of 72) of pinus phenotypes possessed chrysoptera mtDNA, and 12% (17 of 137) of chrysoptera phenotypes possessed pinus mtDNA. Results from much smaller samples from Michigan and Ohio also failed to show any evidence of asymmetric mitochondrial introgression. The results we report here, based on mtDNA and plumage phenotype information for 337 birds representing much of the range of the two species, indicate that previous genetic results and inferences from Pennsylvania may not be broadly applicable to the many areas of contact between chrysoptera and pinus in eastern North America.

Reciprocal Introgression between Golden-Winged Warblers (Vermivora chrysoptera) and Blue-Winged Warblers (V. pinus) in Eastern North America

Reciprocal Introgression between Golden-Winged Warblers (Vermivora chrysoptera) and Blue-Winged Warblers (V. pinus) in Eastern North America

Isolation and characterization of 12 microsatellite loci from Golden‐winged Warblers (Vermivora chrysoptera) with broad cross‐taxon utility in emberizine songbirds

AbstractWe describe 12 microsatellite loci from the Golden‐winged Warbler (Vermivora chrysoptera), a bird species of conservation concern owing to competition and hybridization with the Blue‐winged Warbler (V. pinus). Directional mitochondral DNA introgression from V. pinus into V. chrysoptera has been reported within the hybrid zone. Frequent hybrid phenotypes suggest that nuclear introgression is also prevalent, although this has not been demonstrated conclusively with molecular markers. These microsatellites will foster explorations of the genetic interactions between these avian congeners, and amplification tests suggest that they have high cross‐species utility for closely allied bird genera and families.

Relationship Between Territorial Male Golden-Winged Warblers in Managed Aspen Stands in Northern Wisconsin, USA

Abstract We compared territorial male Golden-winged Warbler (Vermivora chrysoptera) (GWWA) density and territory placement across four size classes [(1) seedling (<2.5 cm mean diameter at breast height (dbh)), (2) small sapling (3.0–6.0 cm dbh), (3) large sapling (7.0–11.5 cm dbh), (4) pole (12.5–17.0 cm dbh)] of aspen forests (Populus spp.) in northern Wisconsin. We surveyed four stands in each size class in May-June 2000 and observed the highest male density (0.55 males/ha) in the seedling size class. Male density for size classes 2–4 combined was 0.04 males/ha. Aspen sucker density was a good predictor of male density across size classes and thus may be a good indicator of habitat quality in aspen communities. Mean GWWA territory area was 0.82 ha (n = 12) in Size Class 1, 0.54 ha (n = 6) in Size Class 4, and 0.18 ha (n = 6) for Size Classes 2 and 3 combined. We found no relationship between male density and the amount of stand edge (km/ha), and territories did not consistently include the stand edge. Because GWWA are strongly associated with aspen seedling stem densities and this aspen stand size class is suitable to GWWAs for a relatively short period of time, we believe conservation will require managing aspen forests to ensure that habitat is always available. Clearcutting aspen forest is a practical strategy to create GWWA breeding cover in the Upper Great Lakes Region. FOR. SCI. 50(2):153–161.

RECIPROCAL INTROGRESSION BETWEEN GOLDEN-WINGED WARBLERS (VERMIVORA CHRYSOPTERA) AND BLUE-WINGED WARBLERS (V. PINUS) IN EASTERN NORTH AMERICA

Abstract Golden-winged Warblers (Vermivora chrysoptera) and Blue-winged Warblers (V. pinus) are small, brightly colored Neotropical migrant birds that breed in eastern North America. Wherever the two species occur together, they hybridize to a limited degree, producing distinctive hybrid phenotypes. In recent decades, chrysoptera has experienced dramatic population declines across much of its range. Those declines have often been correlated with establishment and increase of pinus in the same areas, but it remains uncertain what, if any, role pinus has played in driving the decline of chrysoptera. In a first attempt at molecular genetic analysis of chrysoptera-pinus population dynamics, Gill (1997) reported cryptic, completely asymmetric, and possibly very rapid introgression of pinus mitochondrial DNA (mtDNA) into chrysoptera, causing what he termed “local cytonuclear extinction” of chrysoptera. As Gill (1997) noted, however, those results were based on relatively small samples from a single area in Penn...

Effects of Vegetation, Interspecific Competition, and Brood Parasitism on Golden-Winged Warbler (Vermivora Chrysoptera) Nesting Success

Abstract The recent decline of Golden-winged Warblers (Vermivora chrysoptera) correlates with the loss of suitable nesting habitat, range expansion by Blue-winged Warblers (V. pinus), and eastward expansion of Brown-headed Cowbirds (Molothrus ater). Multivariate statistics were used to examine effects of those factors on Golden-winged Warbler reproduction in north central New York. Herb and shrub cover were positively correlated with clutch size. Blue-winged Warbler proximity was negatively correlated with Golden-winged Warbler clutch size. Tree cover and perhaps herb cover, after adjusting for brood size, correlated with a reduced number of Golden-winged Warbler fledglings. Herbaceous cover correlated with a greater number of cowbird eggs in Golden-winged Warbler nests. Cowbird parasitism correlated with a reduction in the number of Golden-winged Warbler eggs incubated and proportion of incubated eggs that hatched. However, cowbird parasitism, after adjusting for brood size, did not significantly affect nestling success rate. Cowbirds parasitized 30% of Golden-winged Warbler nests, which reduced the number of Golden-winged Warblers fledged by ∼17%. Average herb and tree cover values were 69 and 22 in Golden-winged Warbler territories and 60 and 23 in Blue-winged Warbler territories, respectively, with herb cover significantly greater for Golden-winged Warblers. Territories in the earliest stages of succession used by Golden-winged Warblers supported larger clutches and a reduction in the strong, negative effect of Blue-winged Warbler proximity and an increase in the negative effect correlated with cowbirds, if cowbirds were locally abundant.

EFFECTS OF VEGETATION, INTERSPECIFIC COMPETITION, AND BROOD PARASITISM ON GOLDEN-WINGED WARBLER (VERMIVORA CHRYSOPTERA) NESTING SUCCESS

Abstract The recent decline of Golden-winged Warblers (Vermivora chrysoptera) correlates with the loss of suitable nesting habitat, range expansion by Blue-winged Warblers (V. pinus), and eastward expansion of Brown-headed Cowbirds (Molothrus ater). Multivariate statistics were used to examine effects of those factors on Golden-winged Warbler reproduction in north central New York. Herb and shrub cover were positively correlated with clutch size. Blue-winged Warbler proximity was negatively correlated with Golden-winged Warbler clutch size. Tree cover and perhaps herb cover, after adjusting for brood size, correlated with a reduced number of Golden-winged Warbler fledglings. Herbaceous cover correlated with a greater number of cowbird eggs in Golden-winged Warbler nests. Cowbird parasitism correlated with a reduction in the number of Golden-winged Warbler eggs incubated and proportion of incubated eggs that hatched. However, cowbird parasitism, after adjusting for brood size, did not significantly affect ...

Effects of Vegetation, Interspecific Competition, and Brood Parasitism on Golden-Winged Warbler (Vermivora chrysoptera) Nesting Success

Effects of Vegetation, Interspecific Competition, and Brood Parasitism on Golden-Winged Warbler (Vermivora chrysoptera) Nesting Success

GOLDEN-WINGED WARBLER BREEDING HABITAT CHARACTERISTICS AND NEST SUCCESS IN CLEARCUTS IN THE SOUTHERN APPALACHIAN MOUNTAINS

Abstract Despite widespread population declines, few studies have sought to quantify nesting habitat and reproductive characteristics of Golden-winged Warblers (Vermivora chrysoptera). We characterized territory and nesting habitat and measured productivity in forest regeneration areas in the Nantahala National Forest, North Carolina, and Cherokee National Forest, Tennessee, during 1997–1998. We located 82 territories and monitored 23 nests. Golden-winged Warblers occupied young stands with low basal area and annually mowed daylit roads (roads mowed wider than the track to facilitate drying), and nested in sites with high herbaceous density compared to unoccupied regeneration areas. Nest sites had fewer saplings and less canopy cover than the surrounding territory. Overall nest success was 72.5% and nests fledged an average of 3.65 young. Recently harvested forest stands (age ;le13 yr) with herbaceous cover on logging roads and log landings provided habitat capable of supporting Golden-winged Warbler repr...

Song Perch Characteristics of Golden-winged Warblers in a Mountain Wetland

Abstract I investigated the perch characteristics for “type I” singing (the song type used for mate attraction) by ten territorial male Golden-winged Warblers (Vermivora chrysoptera) in a mountain wetland in North Carolina. Males selected >75% of perches in the upper quarter of canopy trees. Song perches were located in trees larger and closer to forested edges and water than expected by chance. However, not all birds displayed an affinity for water, likely reflecting the uneven distribution of water across the study site. This study suggests that Golden-winged Warblers choose perches that enhance their ability to display vocally and visually to attract a mate. It also indicates that in this mountain wetland, water is an important attribute of Golden-winged Warbler territories.

A Reassessment of the Status of Golden-winged and Blue-winged Warblers in the Hudson Highlands of Southern New York

Populations of Golden-winged Warblers (Vermivora chrysoptera) and Blue-winged Warblers (V. pinus) have coexisted in the Hudson Highlands for a century. Previous researchers in our study area suggested this unusual coexistence might be due to a low frequency of hybrids. However, during the 1998–1999 breeding season we found that 10% of the males were hybrids, a value similar to many studies elsewhere. We observed that hybrid males ceased singing and other conspicuous behaviors early in the breeding season. Pair formation and nesting by hybrids appeared to be rare, perhaps because of the reduced vigor of their displays. Most of the fieldwork by previous researchers in this area was conducted after the date when hybrids cease singing, which may account for prior reports of the absence of hybrids.

Response of breeding birds to shearing and burning in wetland brush ecosystems

In the absence of wildfire, emergent wetlands in the American Midwest often succeed to a shrub/scrub wetland type. Management activities, including shearing and burning are typically used to remove shrub, resulting in a more open emergent wetland condition. We surveyed breeding birds in managed and unmanaged shrub/scrub wetlands in northeast Minnesota, USA, in 1996 and 1997 to examine breeding bird response to management type (burning and shearing) and time elapsed since management. In a comparison of 58 managed sites and 58 unmanaged sites in 1996, unmanaged sites had more (P<0.05) species and individuals than managed sites. In addition, 12 of 20, individual species tested differed significantly (P<0.05) in abundance between the groups. Species associated with emergent wetland type, like the Sedge Wren (Cistothorus platensis) and LeConte’s Sparrow (Ammodramus leconteii) were more, abundant (P<0.05) in managed sites, and species that require shrubs, such as the Alder Flycatcher (Empidonax alnorum) and Golden-winged Warbler (Vermivora chrysoptera) were more abundant (P<0.05) in unmanaged sites. Examination of the effects of management type on breeding birds by either burning, shearing, or, both treatments on sites surveyed in 1997 revealed results similar to comparisons of managed and unmanaged sites completed in 1996. In addition, breeding bird composition, was not different on sites that varied in time elapsed since management. In these latter comparisons, breeding bird species and community composition were similar among all managed sites but differed from the unmanaged sites.

Numts: A Challenge for Avian Systematics and Population Biology

CONFER, J. L. AND K. KNAPP. 1981. Golden-winged Warblers and Blue-winged Warblers: The relative success of a habitat specialist and a generalist. Auk 98:108-114. FICKEN, M. S., AND R. W. FICKEN. 1968. Territorial relationships of Blue-winged Warblers, Goldenwinged Warblers, and their hybrids. Wilson Bulletin 80:161-172. GILL, F. B. 1980. Historical aspects of hybridization between Blue-winged and Golden-winged warblers. Auk 97:1-18. GILL, F. B. 1997. Local cytonuclear extinction of the Golden-winged Warbler. Evolution 51:519-525. GILL, F. B., AND W. E. LANYON. 1964. Experiments on species discrimination in Blue-winged Warblers. Auk 81:53-64. GILL, F. B., AND B. G. MURRAY, JR. 1972. Discrimination behavior and hybridization of the Bluewinged and Golden-winged warblers. Evolution 26:282-293. HANDS, H. M., R. D. DROBNEY, AND M. R. RYAN. 1989. Status of the Golden-winged Warbler in the northcentral United States. United States Fish and Wildlife Service, Twin Cities, Minnesota. HILL, N. P., AND J. M. HAGAN III. 1991. Population trends of some northeastern North American landbirds: A half-century of data. Wilson Bulletin 103:165-182. HOLMES, R. T., T. W. SHERRY, AND F. W. STURGES. 1986. Bird community dynamics in a temperate deciduous forest: Long-term trends at Hubbard Brook. Ecological Monographs 50:201-220. LITVAITIS, J. A. 1993. Response of early successional vertebrates to historic changes in land use. Conservation Biology 7:866-873. MURRAY, B. G., JR., AND F. B. GILL. 1976. Behavioral interactions of Blue-winged and Golden-winged warblers. Wilson Bulletin 88:231-254. RAPPOLE, J. H., AND M. V. McDoNALD. 1994. Cause and effect in population declines of migratory birds. Auk 111:652-660. SAUER, J. R., J. E. HINES, G. GOUGH, I. THOMAS, AND B. G. PETERJOHN. 1997. The North American Breeding Bird Survey home page, version 96.3. Patuxent Wildlife Research Center, Laurel, Maryland. SCHEIDER, F. 1959. Warblers in southern New York. Kingbird 9:13-19. SMITH, C. R., D. M. PENCE, AND R. J. O'CONNOR. 1993. Status of Neotropical migratory birds in the northeast: A preliminary assessment. Pages 172-188 in Status and management of Neotropical migratory birds (D. M. Finch and P. W. Stangel, Eds.). United States Forest Service General Technical Report RM-229, Newton Corner, Massachusetts. WILL, T. C. 1986. The behavioral ecology of species replacement: Blue-winged and Golden-winged warblers in Michigan. Ph.D. dissertation, University of Michigan, Ann Arbor. WITHAM, J. W, AND M. L. HUNTER, JR. 1992. Population trends of Neotropical migrant landbirds in northern coastal New England. Pages 85-95 in Ecology and conservation of Neotropical migrant landbirds (J. M. Hagan III and D. W Johnston, Eds.). Smithsonian Institution Press, Washington, D.C.

Behavioral Interactions between Golden-Winged and Blue-Winged Warblers

The breeding range of the Golden-winged Warbler (Vermivora chrysoptera) has expanded in some regions and contracted in others for more than a century (Gill 1980). The decline of the Golden-winged Warbler often is attributed to loss of breeding habitat and/or interactions with the Blue-winged Warbler (V pinus; Confer and Knapp 1977, 1981; Will 1986; Hands at al. 1989; Confer 1992a,b). Golden-winged Warblers nest in early successional habitat. Abandoned farmland is the precursor of most its nesting habitat, although fires, lumbering, and powerline maintenance also create habitat (Hands et al. 1989). The decline of the Goldenwinged Warbler is part of a widespread reduction in early successional species (Sauer et al. 1997) that is correlated with habitat loss. For example, abandonment of farmland in New Hampshire peaked about a century ago, and early successional habitat was most abundant from 1900 to 1955 (Litvaitis 1993). Since 1955, early successional habitat has decreased to nearly zero. Similar loss of habitat has occurred throughout the reforested northeastern United States, and the abundance of Golden-winged Warblers and other early successional birds has declined (Hill and Hagan 1991, Witham and Hunter 1992, Smith et al. 1993). At the other extreme, the rate of farmland abandonment has increased in Pennsylvania, Minnesota, and Wisconsin from 72,000 ha per year during 1925 to 1960 to 185,000 ha per year from 1960 to 1990 (Census of Agriculture 1935, 1992). Numbers of Golden-winged Warblers increased from 1980 to 1996 (Sauer et al. 1997). Within forested habitats, bird species turnover may continue as young forests mature (Holmes et al. 1986). Rappole and McDonald (1994) speculated that Golden-winged Warblers (but not Blue-winged warblers) have been seriously reduced in numbers as a result of winter-habitat loss.... However, regional declines of Golden-winged Warblers began more than 90 years ago (Gill 1980), before loss of winter habitat was extensive, and their numbers are increasing in the northern portions of their range (Sauer et

LOCAL CYTONUCLEAR EXTINCTION OF THE GOLDEN-WINGED WARBLER.

I compared the mtDNA compositions of two adjacent populations of Vermivora chrysoptera (golden-winged warbler) at different stages of transient hybridization with its sister species V. pinus (blue-winged warbler). Pinus mtDNA introgresses asymmetrically and perhaps rapidly into chrysoptera phenotypes without comparable reverse introgression of chrysoptera mtDNA into replacing pinus populations. Pinus mtDNA was virtually fixed (98%) in an actively hybridizing lowland population with varied phenotypes. Pinus mtDNA increased from 27% (n = 11) in 1988 to 70% (n = 10) in 1992 in successive samples of a highland population in the initial stages of hybridization. This population comprised mostly pure and slightly introgressed chrysoptera phenotypes. The rapid pace of asymmetrical introgression may be the result of initial invasion of chrysoptera populations by pioneering female pinus and/or an unknown competitive advantage of pinus females and their daughters over chrysoptera females.

Local Cytonuclear Extinction of the Golden-Winged Warbler

Local Cytonuclear Extinction of the Golden-Winged Warbler

Golden-winged Warbler (Vermivora chrysoptera)

Golden-winged Warbler (Vermivora chrysoptera)

Allozymes and Genetic Similarity of Blue-Winged and Golden-Winged Warblers

I studied variation in plumage color and allozymes in Golden-winged Warblers (Vermivora chrysoptera) from Minnesota and in Blue-winged Warblers (V. pinus) from Missouri and from eastern Pennsylvania. Color character scores were less than 2 in Missouri pinus and greater than 26 in Minnesota chrysoptera. The level of genetic divergence (D = 0.001) is comparable to that of conspecific populations of other passerine birds. I found no fixed alleles that could serve as genetic markers for studies of the evolutionary genetics of these warblers.

Golden-Winged Warbler at Duck Mountain, Saskatchewan

Golden-Winged Warbler at Duck Mountain, Saskatchewan

Brewster's Warbler, Vermivora chrysoptera X pinus backcross, breeding in Huntingdon County, Quebec

Brewster's Warbler, Vermivora chrysoptera X pinus backcross, breeding in Huntingdon County, Quebec