We present historic and contemporary information on the distribution and abundance of Buff- breasted Sandpipers (Tryngites subruficollis ) in South America. Historic information was collated from the literature, area ornithologists, and museums, whereas contemporary data were derived from surveys conducted throughout the main wintering range in Argentina, Uruguay, and Brazil during the austral summers of 1999 and 2001. Variable circular plot sampling was used to estimate population densities. During 1999, the highest concentration of Buff- breasted Sandpipers in Argentina was in southern Bahia Samborombon (General Lavalle District) and areas north of Mar Chiquita coastal lagoon. During 2001, the highest concentrations in Brazil were at Ilha da Torotama and Lagoa do Peixe National Park. During 1999 and 2001, the highest concentrations of Buff-breasted Sandpipers in Uruguay were found along three lagoons (Laguna de Rocha, Laguna de Castillos, and Laguna Garzon) bordering the Atlantic Ocean. Population densities (birds/ha) of Buff-breasted Sandpipers were 0.11 (95% C.I. 5 0.04-0.31) in Argentina, 1.62 (0.67-3.93) in Brazil, and 1.08 (0.37-3.18) in Uruguay. High turnover rates at survey sites, due to the formation of large, mobile flocks, contributed to moderately large confidence intervals around our population density estimates. Nevertheless, compared with historic accounts of Buff-breasted Sandpipers, our survey data indicate the population size of this species has declined substantially since the late 1800s and contemporary information suggests the species has continued to decline during the past three decades. Buff-breasted Sandpipers were found almost exclusively in pasturelands and appear to depend heavily upon intensive grazing by livestock, which maintain suitable short grass conditions. We discuss the need for protection of critical areas and proper range management to ensure appropriate habitat remains available for the species, and provide suggestions for future research needs. Received 12 March 2001, accepted 31 January 2002. Buff-breasted Sandpipers (Tryngites sub- ruficollis ) probably numbered in the hundreds of thousands at the turn of the Twentieth Cen- tury (Forbush 1912, Hudson 1920). Long term shorebird surveys in central and eastern Can- ada indicate that the population size may be as low as 15,000 today (Brown et al. 2001, Morrison et al. 2001). This decline is attri- buted to commercial hunting during the late 1800s and early 1900s during the species' mi- 1
Most female birds have only a left ovary and associated oviduct. The entry to the oviduct is on the left side of the urodeum of the cloaca. This arrangement may favor males that mount females from the left during copulation if it results in sperm being placed closer to the opening of the oviduct. Therefore, we predicted a left-sided directional bias of cloacal contacts during House Sparrow (Passer domesticus) copulations. Cloacal contacts from the left outnumbered those from the right 74 to 25 (3:1) during 25 bouts of copulation at 11 House Sparrow nests. While this pattern suggests that a left-sided bias in mounting by males during copulation may be related to the asymmetry of the female reproductive tract, it also might be related to brain lateralization.
Clearcutting is the preferred timber harvest method in bottomland hardwood forests because it is most likely to result in regeneration of preferred species. However, clearcutting generally has negative impacts on forest birds. Patch-retention harvesting may provide similar silvicultural benefits, but its effects on birds are unknown. We surveyed breeding birds in uncut control, clearcut, and patch-retention treatment areas (11-13 ha) for one season prior to harvest and two seasons postharvest in a bottomland hardwood forest in the Lower Coastal Plain of southeastern South Carolina. Bird observations recorded along line transects were analyzed using the software EstimateS to estimate species richness and program Distance to estimate densities. We found greater species richness and bird densities in the patch-retention treatment than in the clearcut in both postharvest seasons. We detected no forest-interior birds in the clearcut after the harvest, but by the second postharvest season in the patch-retention treatment, the density of forest-interior birds had returned to approximately half of its preharvest level. Thus, based on density response, patch-retention harvesting appears to be less detrimental to forest birds than clearcutting. However, additional work is needed to determine whether retained patches influence avian survival and productivity.
Throughout western North America, Red-naped Sapsucker (Sphyrapicus nuchalis) nests have been previously described primarily in trembling aspen (Populus tremuloides) with decy-softened wood. During 1974-1992, we located Red-naped Sapsucker nest trees (n = 125) in northwestern Montana old-growth coniferous forest that included widely scattered paper birch (Betula papyrifera). Sapsucker nests were in nine tree species (seven conifers). Most (68%) nest trees were live and 75% had broken tops. Western larch (Larix occidentalis) and birch were greatly over utilized compared to their availability. Larch nest trees (n = 84) were large [mean DBH = 69 ± 20.95 (SD) cm]. Mean DBH of birch nest trees (n = 30) was 37 ± 8.42 cm. All Mountain Chickadee (Poecile gambeli) nests (n = 36) and 12 of 23 Red-breasted Nuthatch (Sitta canadensis) nests were in old sapsucker excavated nest holes. Wood of larch and birch is inherently harder than that of aspen (specific gravity = 0.48, 0.48, and 0.35 respectively), posing a potential obstacle for relatively weak excavators such as sapsuckers. However, the entire inner wood column of birch is susceptible to decay fungi and the durable bark is thin. In larch sapsuckers mitigated the difficulty by selecting trees with extensive heartwood decay (old larch) and by excavating in the upper bole (mean cavity height = 21.5 m), where the bark is thinner. External evidence of heartwood decay was present in 87% of larch and 86% of birch. Decay incidence increases with age in western larch forests, amplifying their value as habitat for sapsukers and many other species. Perpetuation of old-growht western larch is an important component in the conservation of biological diversity.
Mice in the Freezer, Owls on the Porch is in many ways a love storyâabout a quiet scientist and his flamboyant wife, but also about their passions for hunting, for wild lands, and for the grouse and raptor species that they were instrumental in saving from destruction. From the papers and letters of Frederick and Frances Hamerstrom, the reminiscences of contemporaries, and her own long friendship with this extraordinary couple who were her neighbors, Helen Corneli draws an intimate picture of Fran and "Hammy" from childhood through the genesis and maturation of a romantic, creative, and scientific relationship. Following the Hamerstroms as they give up a life of sophisticated convention and comfort for the more "civilized" (as Aldo Leopold would have it) pleasures of living and conducting on-the-spot research into diminishing species, Corneli captures the spirit of the Hamerstroms, their profession, and the natural and human environments in which they worked. A nuanced account of the labors, adventures, and achievements that distinguished the Hamerstroms over the yearsâand that inspired a generation of naturalistsâthis book also provides a dramatic account of conservation history over the course of the twentieth century, particularly in Wisconsin during the eventful years from the 1920s through the 1970s.
We review ornithology in Belize, formerly British Honduras, since Russell's 1964 monograph and summarize published and unpublished reports, banding records, and museum data. Unpublished reports (gray literature) are an important source of information within the country. Since 1960, there have been numerous studies by the British Forces ornithological societies and others on avian ecology and behavior. the effects of logging on birds, the distribution of overwintering Neotropical migrants (approximately 20% or Belize's avifauna), and comparisons of avian distribution in disturbed versus undisturbed habitat. We review recent distributional records and problematic species records requiring verification and identify distributional "knowledge gaps" Although 70% of the country is stilt dominated by natural vegetation and 20% falls under some form of protected status, certain bird species and families are at risk from human impacts such as habitat conversion, hunting, introduced species, and in some cases, tourism. Areas for future study are suggested.
We observed, tape recorded, and photographed birds of the Alaka'i Plateau on Kaua'i, Hawai'i for one week during the summer of 1975. We observed all but one of the island's historically known species and compared the Alaka'i Plateau with the more accessible Koke'e area Ours were the last studies before catastrophic changes in the Kaua'i avifauna and included many observations that cannot now be repeated. This retrospective report presents our Endings in the light of subsequent events. Because our Alaka'i studies were seminal in the development of the current AOU classification of Hawaiian native passerines, we defend that classification against recent challenges and further refine it. The controversial genus Hemignathus is shown to be supported by a suite of synapomorphies of plumage, bill morphology, and vocalizations. We advocate removal of the 'Anianiau from Hemignathus and classify it as Magumma parva. Our studies of foraging behavior and vocalizations support the recent recognition of the Kaua'i 'Amakihi (H. kauaiensis) as a separate species and suggest that the 'Elepaio (Chasiempis) is best split into three species (sclateri, ibidis, and sandwichensis) Major hurricanes in 1983 and 1992 appear to have severely impacted Alaka'i bird populations with the subsequent extinction of the Kaua'i 'O'o (Moho braccatus) and possibly the Kama'o (Myadestes myadestinus), and the island population of 'O'u (Psittirostra psittacea). We report some of the last natural history observations on these species Formerly adaptive strategies for storm survival, including taking refuge in valleys, are no longer effective because the lowlands are now infested with mosquito-borne avian diseases. The Puaiohi (M. palmeri), a ravine specialist, suffered less from the storms although its population remains perilously low. Other forest birds, especially the 'Akikiki (Oreomystis bairdi), show noticeable declines since 1975. We speculate that introduced organisms such as alien plants can have a deleterious effect on ecosystems by altering feeding methods of birds even in areas where the weeds do not occur. We caution against the overly conservative use of species-level taxa for setting conservation priorities on remote islands.
Thirty-seven colony sites were used by nine species of nesting wading birds (Ciconiiformes) in the Corkscrew Swamp area (2320 km2) of southwestern Florida during a four-year census. Yearly turnover in colony site use averaged 30-40% with a maximum of 25 active colonies in any one year. The number of species nesting in a colony was correlated with the year to year stability of the colony. Fewer colonies formed during drought years. Colony formation occurred later in a season that followed 18 months of below normal rainfall. The location and timing of nesting by colonial wading birds (Ciconi-iformes) are correlated with surface water conditions and feeding oppor-tunities (Kahl 1964, Kushlan et al. 1975, Kushlan 1976, Ogden et al. 1980). This study was designed to document the species abundance in an area around Corkscrew Swamp Sanctuary of the National Audubon So-ciety in southwestern Florida, and to examine the relationship between rainfall, nesting, and colony locations. The goal of this study was to show responses by nesting wading birds to annual rainfall patterns on a regional rather than individual colony basis.
We used hourly counts of Red tailed Hawks (Buteo jamaicensis) migrating at Hawk Mountain during the autumns of 1992, 1993, and 1994, to examine the possibility that the extent to which time of day and local weather parameters affected the numbers of birds seen at the site varied over the course of autumn migration. Data were analyzed separately for early-, mid-, and late season periods of migration. High versus low windsM, following versus opposing winds, low versus high relative humidity, and high versus low barometric pressure were associated with increased hourly passage rates of Red-tailed Hawks Relative humidity had a greater effect during early-season migration. Wind speed and wind direction had greater effects during late season migration. We suggest that shills in the extent to which weather affects the numbers of Red-tailed Hawks seen at Hawk Mountain Sanctuary result from seasonal shifts in the species' dependence on thermal versus slope soaring.
The semiarid region of Chile is influenced by El Nino Southern Oscillation. Its absence causes droughts and its presence causes wet years, which in turn result in variations in resource levels for avian assemblages. We show that bird species richness and density follow some of these pulses closely. Sixty-one bird species, 32 of which were Passeriformes, were sighted during five years in Las Chinchillas National Reserve (300 km N of Santiago). Overall, 30 species (49%) were residents and 31 (51%) were migratory. The most speciose trophic groups were insectivores (34%), carnivores (28%), and granivores (25%). Bird species richness and density declined from 43 species and 45-50 individuals/ha in spring 1993, to 29 species and 15-20 individuals/ha in autumn 1996. Increases were observed with the onset of El Nino, reaching totals of 42 species (a 45% increase from 29) and densities of 55-60 birds/ha in summer 1997. Similar trends were observed in one of two major food resources measured: small mammals. Positive correlations were found between raptor species richness and density and small mammal density, but not between insectivorous bird species richness or density and terrestrial arthropod abundance. Because the climate was very dry during most of the time of our study, we may have witnessed the lowest boundary for species richness and bird density. Whether the 1997-1998 El Nino brought the maximum bird species richness and density for the site is yet to be seen.
We used radio telemetry to record 198 h of feeding behavior of five Lesser Scaup (Aythya affinis) on the Indiana Harbor Canal in northwestern Indiana during January and February 1994. Lesser Scaup fed for short periods of time intermittently during each 24-h period. Lesser Scaup fed a total of 96 min during the day and 226 min during the night. They fed more between sunset and midnight (31.9% of the period, P = 0.003) than between sunrise and noon (11.6%) or noon and sunset (19.5%); time spent feeding between midnight and sunrise (26.3%) did not differ from other times of day. Mean dive duration (22.9 ± 0.64 sec) did not vary by time of day (P = 0.186- 0.744). These results are the first 24-h feeding activity reported for individually marked Lesser Scaup.
Using standardized mist-net captures collected over a 32-year period (1970-2001), we examined changes in the capture rates of passerines recorded in coastal Massachusetts during fall (78 species) and spring (72 species) migration. Capture rates of 45 species of fall migrants (58%) declined significantly between early (1970-1985) and late (1986-2001) years of the study; 36 species of spring migrants (50%) showed significant declines. Only Carolina Wren (Thryothorus ludovicianus), Tufted Titmouse (Baeolophus bicolor), Northern Cardinal (Cardinalis cardinalis), and Orchard Oriole (Icterus spurius) showed significant increases during spring migration; fall sampling indicated that Carolina Wren, Tufted Titmouse, Black-throated Blue Warbler (Dendroica caerulescens), and Northern Cardinal had significantly higher capture rates. Of 37 species included in the migration monitoring data but not reliably represented by Breeding Bird Survey (BBS) data in any of the northeastern physiographic strata, 23 (62%) showed significant declines at Manomet during at least one of the two migration periods. There were significant correlations in percent changes in migrant capture rates between fall and spring. BBS trends reported from the southern New England and northern New England physiographic strata were correlated with changes in migrant capture rates. However, there were also inconsistencies between results obtained by the two monitoring approaches, suggesting that factors in addition to actual changes in breeding populations may be reflected in the migration capture data.
The eastern Gulf of Alaska coastline is suspected of providing an important pathway for birds migrating to and from Alaska. Because no intensive study of landbird migration has been conducted in this region, we used mist nets to study the post-breeding migration of landbirds along the coast from 1994 through 1999. Over six post-breeding periods, we netted for a total of 316 days (23,538 net-hr) and captured 13,490 individuals of 46 species (57.3 birds/100 net-hr). Six species constituted >65% of all captures (ordered by abundance): Orange-crowned Warbler (Vermivora celata), Hermit Thrush (Catharus guttatus), Lincoln's Sparrow (Melospiza lincolnii), Ruby-crowned Kinglet (Regulus calendula), Fox Sparrow (Passerella iliaca), and Yellow Warbler (Dendroica petechia). Most birds captured (71%) were Nearctic-Neotropical migrants, and percentages of hatching-year (HY) birds varied from 51 to 90% among common species. Daily capture rates of all species were highest between mid-August and mid-September. Migration of HY individuals preceded that of after-hatching-year (AHY) birds in 70% of the Nearctic-Neotropical species. Masses of HY Nearctic-Neotropical migrants were significantly less than those of AHY individuals. High capture rates and consistent annual use indicate that the eastern Gulf of Alaska coast is an important pathway for many small landbird migrants, particularly Nearctic-Neotropical species, departing breeding grounds in southern Alaska.
We monitored wetland habitat use and inter-wetland moves of 52 Mallard (Anas platyrhynchos) broods near Yorkton, Saskatchewan. Brood-attending females were equipped with radio transmitters and their locations monitored daily. Duckling survival in the first two weeks after hatching was not related to distance traveled to the first wetland nor the total distance traveled overland in the 14-day period. Brood-rearing females were found on one to five wetlands in the first week after hatch (mode = 2), and most (17 of 32) remained on one wetland in the second week (range = 1-5). Broods were found most frequently (69 - 95% of days) on semi permanent wetlands. Conductivity on most (>95%) of these wetlands was <2000 microsiemens/cm; such levels are well below those known to affect duckling growth or survival. For 12 broods for which we had data on food (chironomid) abundance, we were unable to detect a relationship between inter-wetland movements and brood use. Nor was there evidence that duckling survival was related to levels of chironomid abundance.
We compared numbers of forest bird territories between forest edge and forest interior areas to determine whether clearcuts affect bird abundance in adjacent forest. We then simulated the distribution of territories that would be expected if birds were neither attracted to nor repelled by clearcut borders by randomly locating 100 1-ha circular 'simulated' territories on scale maps of the study plots, with the condition that simulated territories were located entirely within mature forest. Plots were divided into successive 50-m distance classes extending from clearcut borders 300 m into forest interior, and the distribution of territories of each species among 50-m distance classes was compared with the distribution of simulated territories. Red-eyed Vireos (Vireo olivaceus) and Hermit Thrushes (Catharus guttatus) were less abundant in edge areas, but the distribution of these species did not differ from the distribution of randomly placed simulated territories. We conclude that lower abundance of forest birds in edge areas is not necessarily evidence of edge avoidance but may be merely the result of the absence of suitable habitat beyond clearcut borders.
Introduced grass dominated Conservation Reserve Program (CRP) fields were monitored in summer 1992 in Gratiot County. Michigan, to determine the relationship between field age and avian relative abundance, diversity, and productivity. Younger CRP fields (1-2 years old), best described as a combination of forbs and bare ground, had the greatest diversity and relative abundance of avian species. Older CRP fields (3-5/6 years old) were a combination of grasses and deep litter cover and had the greatest avian productivity. We recommend that alter 3-5 growing seasons CRP fields be manipulated to provide a variety of successional stages to maintain simultaneously high avian relative abundance, diversity, and productivity.
I censused Herring, Ring-billed, and Laughing gulls (Larus argentatus, L. deluwarensis, L. utricih) at two landfills near Tampa Bay, Florida, from October 198 1 to April 1984. Gulls were most abundant during mid-winter; Herring and Ring-billed gulls were nearly absent from landfills from May through October. At least 90,000 gulls foraged at seven bay-area landfills during January and February. Landfills appear to be an important food resource for all three gull species wintering on the west-central coast of Florida. Changing waste disposal practices from landfilling to incineration are likely to affect them greatly.
Whip-poor-wills Caprimulgus vociferus were significantly more numerous in forested habitat than Chuck-will's-widow C. carolinensis and the opposite was true in open habitat. Whip-poor-wills were significantly more numerous in forested habitat than in open or suburban areas. Chuck-will's-widows were approximately equally abundant in all 3 habitat types. Change in land use from agriculture to forest is offered as a partial explanation for the south-ward range expansion of the whip-poor-will. Moon phase showed the strongest correlation with numbers of singing birds.-from Author
We investigated the use by Brown-headed Cowbirds (Molothrus ater) of five forest edge types and the forest interior of Green Ridge State Forest in the ridge and valley physiographic province of Maryland. Habitats were sampled, and breeding birds counted at each site. Cowbirds were detected in all habitats except forest interior; occurring most frequently in forest-brush (50.0% of points), -stream (46.3%), and -powerline (33.3%) edges. Among edge types, snag BA was also significantly (P < 0.01) higher at forest-powerline, -brush, and -stream edges than at forest-open road and -closed road edges. These habitats had high total vegetation volume (TVV), with which bird and host species abundances were positively associated. However, high TVV was not always indicative of high snag BA. With all habitats combined, bird species abundance, total vegetation volume (TVV), and foliage height diversity (FHD) at a height of 1-2 m were significantly (P < 0.05) higher at points where cowbirds were detected than at those where they were not detected, however only bird species abundance remained significant (P = 0.059) when forest interior was removed from the analysis. We propose that cowbirds in western Maryland select breeding areas based on: (1) distinct visible edges formed by canopy openings in the forest landscape, (2) occurrence of both high snag BA and high TVV at the forest edge, and (3) presence of high bird species abundance.
Woodpeckers were censused in 60 fixed-radius (300 m) circular plots (divided into eight 45 degrees-arc pie-shaped sectors) in mature forests (60-80 years-old) of three forest types (20 plots per type) in eastern Texas: bottomland hardwood forest, longleaf pine (Pinus palustris) savannah, and mixed pine-hardwood forest. A total of 2242 individual woodpeckers of eight species was detected in 144 h of censusing. Vegetation characteristics in plot sectors with and without woodpeckers were compared. Woodpecker presence and abundance were primarily associated with the occurrence of large snags and logs. Red-bellied Woodpeckers (Melanerpes carolinus) were the most abundant and widespread species, especially in areas containing more hardwoods that? pines. Red-cockaded Woodpeckers (Picoides borealis) were the least abundant and most habitat-restricted woodpecker, occurring only in the longleaf pine savannah. Pileated Woodpeckers (Dryocopus pileatus) were the must evenly distributed species among the forest types, but occurred primarily in mature forests with large snags and logs. Bottomland hardwood forests were important for Northern Flickers (Colaptes auratus), Redheaded Woodpeckers (Melanerpes erythrocephalus), and Yellow-bellied Sapsuckers (Sphyrapicus varius) during the fall and winter, and for Downy Woodpeckers (Picoides pubescens) during the summer and winter. Thr Hairy Woodpecker (P. villosus) was most frequently encountered in areas of recent disturbance in the mixed pine-hardwood forests, especially in fall. Vocal imitation of a Barred Owl (Strix varia) increased the number of woodpecker detections by 71%.
Ghost crabs (Ocypode quadrata) have been implicated in mortality of eggs and chicks of the beach-nesting Piping Plover (Charadrius melodus) whose Atlantic Coast populations are listed as threatened. Through observation and experimentation, we investigated the interactions between ghost crabs and plovers on Wild Beach, a Piping Plover nesting area on Assateague Island, Virginia. This site has a high abundance of ghost crabs and historically low hedging success compared to adjacent areas with fewer crabs. We observed encounters of crabs with plover eggs, chicks, and adults in the field, but never predation. In staged encounters of crabs with eggs and chicks (using hatchery reared quail as plover surrogates), we were unable to elicit predatory behavior either on the beach or in the lab. We conclude that although instances of ghost crab predation on Piping Plover eggs and chicks occur, they are rare and cannot account for the high mortality frequently reported on beaches where ghost crabs are abundant. Adult plovers behave toward crabs as if they were dangerous to eggs and chicks, and their young broods in the study area did not forage along the foreshore. Hence, ghost crabs may increase mortality indirectly. Frequent responding to crabs by parents may attract more deadly brood predators. Brood nutrition may suffer as adult plovers direct chicks away from areas where forage is reportedly richer but crabs are abundant, such as the foreshore. Nutrient intake may be further reduced on more southerly breeding grounds where high temperatures on backshores force chicks to stop foraging and take shelter during mid-day. Although high mortality cannot be attributed directly to predation by crabs, it may be due to factors that covary with crab abundance, such as high temperature, behavioral responses of adult birds, and poor forage.
From 1993-1995, we located and monitored 601 Acadian Flycatcher (Empidonax virescens) nests in a large contiguous tract of bottomland hardwood forest on the White River National Wildlife Refuge, Arkansas. Annual reproductive success was significantly different among years; ranging from 10-25% (Mayfield estimate) over the three years of the study. There was no significant difference in nest success among study plots, with nesting success showing a trend of increasing late in the breeding season. Clutch size for nonparasitized nests averaged 2.9 ± 0.02 (SE) eggs with a mode of 3. Rates of Brown-headed Cowbird (Molothrus ater) parasitism were low (21%), accounting for 7% of all nest failures. However, parasitism by cowbirds resulted in a reduction of clutch size for nests initiated early (i.e., first nests and replacements) in the breeding season. Predation was the leading cause of nest failures, accounting for 75% of all failures. Snakes and avian predators were thought to be the leading cause of nest failures. Although additional factors must be investigated, preliminary results indicate that nest predation is a major influence on this population, despite the size of the forest tract.
Male American robin behave in ways consistent with the protection of paternity hypothesis. During nest building and egg laying, when females are fertilizable, males are with females significantly more often than they are during incubation when females are assumed to be nonfertilizable. Males are significantly closer to females and follow them significantly more often during fertilizable than nonfertilizable periods. Male behavior is a probable result of selective advantage gained through paternity assurance, though not necessarily through mate-guarding. -from Authors
The determination of body condition of birds is important for many field studies. However, when using trapping methods based on food as a lure, the sample of trapped birds could be biased toward individuals in poor physical condition. We provide information on body mass, body condition, and sex and age ratio of Levant Sparrowhawks (Accipiter brevipes) and Eurasian Sparrowhawks (Accipiter nisus) caught in Elat, southern Israel, during spring migration. We compared physical condition of birds trapped in baited traps to physical condition of birds trapped in mist nets (no bait). The body mass and index of physical condition of migrating Levant Sparrowhawks trapped in baited traps was lower than birds trapped in mist nets. By comparison no differences were detected in body mass and condition index of migrating Eurasian Sparrowhawks caught by the different trapping methods. The differences found in condition of Levant Sparrowhawks trapped with and without food support the predictions of the condition-bias hypothesis; however, data from the Eurasian Sparrowhawk do not. The extent to which biases occur may be different even for closely related species.
MERICAN Woodcock (Philohela minor) wintering in Louisiana have A long been known to concentrate at night in certain fields (Glasgow, 1958). During the fall, Pettingill (1936) noted woodcock flying at dusk into fields at Cape May, New Jersey. Not until the studies of Sheldon (l%l) in Massachusetts were woodcock reported entering fields after sunset during summer months. Summer utilization of fields has since been found to occur over much of the species' breeding range, including West Virginia (Kletzly and Rieffenberger, 1967)) New Brunswick (J. C. Baird and T. G. Dilworth, pers. comm.) , and Wisconsin (L. E. Gregg, pers. comm.) . Such widespread observations suggest that usage of clearings during summer nights is a char-acteristic behavior pattern of the species. The activities of woodcock using these fields have not been well docu-mented, although Sheldon (1961, 1967) p resented some relevant information. The present paper results from a study undertaken in Maine during the sum-mers of 1968 and 1969. Specifically, it documents the initiation, magnitude, and termination of summer field usage; timing of crepuscular flights; move-ments of birds between fields; and the age and sex composition of woodcock captured on Maine summer fields. While this paper does not specifically describe what woodcock do on fields at night, the data presented should be useful to persons desiring to locate and band woodcock on nocturnal fields. METHODS The fields studied were located in, or near, southern Penobscot County in central Maine. I made observations in 14 fields, with two of these, Rebel Hill and Sunkhaze, selected for intensive investigation. The areas studied were abandoned farm fields having a vegetative cover of grasses, hawkweeds (Hieracium spp.1, and various species of woody plants, including meadow-sweet (Spiraea Zatifolia) and sweet-fern (C~mptonia peregrina) . Rebel Hill and Sunkhaze, 5.0 and 4.5 hectares in size, were each visited at least two evenings a week during the sprin, o-of 1968 to determine when woodcock first remained on the fields throughout the night. Both fields were systematically searched after dusk at least once a week throughout the summer and fall by one to four, but generally two, observers walking parallel transects 4 to 7 meters apart. The locations of woodcock flushed were plotted on maps to document the distribution and number of birds found. Each observer carried a spotlight and 12 volt battery; some woodcock were captured with a long-handle net. Although only a small percentage of the woodcock found were cap-tured and banded, these birds provided information on movements between fields. An account of the night-lighting technique is given by Rieffenberger and Kletzly (1967). Some birds were also captured in mist-nets while flying into fields, a method described by Sheldon (1960).