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At least 559 records · Page 31Linked to original sources
USGS1980

The effect of band loss on estimates of annual survival

Banding has proven to be a useful technique in the study of population dynamics of avian species. However, band loss has long been recognized as a potential problem, (Hickey, 1952; Ludwig, 1967). Recently, Brownie et al. (1978) presented 14 models based on an array of explicit assumptions for the analysis of band recovery data. Various estimation models (assumption sets) allowed survival and/or recovery rates to be (a) constant, (b) time-specific, or (c) time- and age-specific. Optimal inference methods were employed and statistical tests of critical assumptions were developed and emphasized. The methods of Brownie et al. (1978), as with all previously published methods of which we are aware, assume no loss of bands during the study. However, some band loss is certain to occur and this potentially biases the estimates of annual survival rates whatever the analysis method. A few empirical studies have estimated band loss rates (a notable exception is Ludwig, 1967); consequently, for almost all band recovery data, the exact rate of band loss is unknown. In this paper we investigate the bias in estimates of annual survival rates due to varying degrees of hypothesized band loss. Our main results are based on perhaps the most useful model, originally developed by Seber (1970), for estimation of annual survival rate. Inferences are made concerning the bias of estimated survival rates in other models because the structure of these estimators is similar.

Journal of Field Ornithology↗
USGS1985

Determining age and sex of American coots

Reliable techniques for age and sex determination of migrating and wintering American Coots ( Fulica americana ) have not been available. Breeding coots can be ages through age 3 by tarsal color (birds 4 years and older were placed in a 4+ age class) (Crawford 1978), and males and females have sex-specific behaviors and calls while on breeding territories (Gullion 1950, 1952). Externally, juvenile coots differ from adults in having gray (as opposed to white) bills and brown (as opposed to red) eyes to an age of 75 days (Gullion 1954-394). Bill color changes to white by about 120 days. No quantitative data have been available, however, on the proportion of juveniles retaining these traits throughout fall and early winter. Nonbreeding coots can be ages as juvenile or adult by internal examination of the thickness of the wall of the bursa of Fabricius, although bursal depth does not predictably decline with age (Fredrickson 1968). Attempts to sex coots by single external measurements of combinations of measurements have met with mixed success. Eight-five percent of 101 fall migrants in Wisconsin could be sexed by the length of the metatarsus-midtoe including claw by using 139.5 mm as a cutoff point (Burton 1959), whereas 88% of 67 coots in California were correctly sexed by the length of the metatarsus-midtoe without claw using 127.5 mm as the cutoff point (Gullion 1952). Two-hundred-thirty-two of 291 coots collected in Iowa, however, were in the zone of overlap between the sexes for this measurement (Fredrickson 1968). Previous studies attempting to develop aging and sexing techniques for American Coots have been limited to a few study sites or to 1 season or year, often failing to take geographical, annual, and seasonal morphological variation into account (e.g., Visser 1976, Fjeldsa 1977). We designed the present study to refine and quantify external and internal age and sex criteria for postbreeding coots, with the objective of defining techniques applicable for all seasons over a wide geographical area.

Journal of Field Ornithology↗
USGS1993

Growth and survival of Mountain Plovers

Growth and survival rates of Mountain Plovers ( Charadrius montanus ) were monitored using radiotelemetry from hatching until birds left the breeding grounds on the Pawnee National Grassland, Weld County, Colorado. Chick weights increased logarithmically ( r ) = 0.961) and tarsus length linearly ( r = 0.948) with age. Using the average fledgling weight of 69.8 g and an age/weight regression we predicted that the average age at fledging was 36 d. Fourteen Mountain Plover nests each had three effs; an average of 2.6 eggs hatched in seven nests, whereas remaining nests were lost to predation, storms, or trampling by a cow. Twenty-four adult Mountain Plovers were monitored for 275 telemetry days with no mortalities. Twenty flightless chicks had a calculated daily survival rate of 0.979 for 233 telemetry-days. Mortalities of flightless chicks were due to predation or unknown causes. The daily survival rate predicted that 1.2 of the 2.6 chicks hatched per nest lived to fly. Eight fledged chicks were monitored for 74 telemetry-days, with a daily survival rate of 0.974. Mortalities of fledglings were all attributed to predation. The combined survival rates predicted that 0.7 or the 2.6 hatched chicks lived to leave the nesting area. Survival rates of flightless chicks were similar to those reported 20 yr ago, implying that recent declines in Mountain Plover numbers on the continent are not attributable to either longer-term declines in nesting productivity or phenomena occurring at non-breeding locales.

Journal of Field Ornithology↗
USGS1993

Nests and nest sites of the San Miguel Island Song Sparrow

Nests and nest sites of the San Miguel Island ( SMI ) Song Sparrow ( Melospiza melodia micronyx ) are described; nests are compared with those of 16 other races of Song Sparrows. Bush lupins ( Lupinus albifrons ), coyote brush ( Baccharis pilularis ) and golden bush ( Haplopappus venetus ) were the shrubs used most commonly as nest sites by Song Sparrows on SMI. As a result of its location, the nest was effectively concealed from gray foxes ( Urocyon littoralis ), the major predator of this sparrow. Nest and nest site also moderated the combined chilling effects of cool air temperatures and strong northwesterly winds on the eggs and nestlings. Even in the absence of these moderating effects of the nest site, the energetic cost of incubation, estimated at 41-53% of the sparrow's resting metabolic rate, was modest. Twenty-nine percent of the canopy above the nest was open and as much as 73% of the nest cup was in the sun at midday, a time when surface temperatures of foliage, nest and nestlings sometimes exceeded 40 C. Whereas this exposure did not apparently reduce fledging success, it may explain why the incidence of addled eggs was so high in this population of Song Sparrows compared to others. Significant differences existed among races of Song Sparrows in the size, porosity and insulation of the nest. In most cases, these differences were not related to the latitude of the races' nesting areas.

California↗
USGS2011

Status and distribution of the Kittlitz's Murrelet Brachyramphus brevirostris along the Alaska Peninsula and Kodiak and Aleutian Islands, Alaska

The Kittlitz's Murrelet Brachyramphus brevirostris is adapted for life in glacial-marine ecosystems, being concentrated in the belt of glaciated fjords in the northern Gulf of Alaska from Glacier Bay to Cook Inlet. Most of the remaining birds are scattered along coasts of the Alaska Peninsula and Aleutian Islands, where they reside in protected bays and inlets, often in proximity to remnant glaciers or recently deglaciated landscapes. We summarize existing information on Kittlitz's Murrelet in this mainly unglaciated region, extending from Kodiak Island in the east to the Near Islands in the west. From recent surveys, we estimated that ~2400 Kittlitz's Murrelets were found in several large embayments along the Alaska Peninsula, where adjacent ice fields feed silt-laden water into the bays. On Kodiak Island, where only remnants of ice remain today, observations of Kittlitz's Murrelets at sea were uncommon. The species has been observed historically around the entire Kodiak Archipelago, however, and dozens of nest sites were found in recent years. We found Kittlitz's Murrelets at only a few islands in the Aleutian chain, notably those with long complex shorelines, high mountains and remnant glaciers. The largest population (~1600 birds) of Kittlitz's Murrelet outside the Gulf of Alaska was found at Unalaska Island, which also supports the greatest concentration of glacial ice in the Aleutian Islands. Significant populations were found at Atka (~1100 birds), Attu (~800) and Adak (~200) islands. Smaller numbers have been reported from Unimak, Umnak, Amlia, Kanaga, Tanaga, Kiska islands, and Agattu Island, where dozens of nest sites have been located in recent years. Most of those islands have not been thoroughly surveyed, and significant pockets of Kittlitz's Murrelets may yet be discovered. Our estimate of ~6000 Kittlitz's Murrelets along the Alaska Peninsula and Aleutian Islands is also likely to be conservative because of the survey protocols we employed (i.e. early seasonal timing of surveys, strip transects).

Alaska↗
USGS2015

Factors affecting the reproductive success of American Oystercatchers Haematopus palliatus on the outer banks of North Carolina

We used an information-theoretic approach to assess the factors affecting the reproductive success of American Oystercatchers Haematopus palliatus on the Outer Banks of North Carolina. We evaluated survival with respect to nesting island, year, time of season, brood age, distance to tide (m), presence of off-road vehicles and proximity of foraging habitat. The daily nest survival (mean 0.981, standard error [SE] 0.002) was affected by year and island, and declined over the nesting season. Mammals were responsible for 54% of identified nest failures. Daily brood survival (mean 0.981, SE 0.002) varied by island and increased non-linearly with age, with highest mortality in the seven days after hatching. Model results indicate direct access to foraging sites has a positive effect on brood survival, whereas presence of off-road vehicles has a negative effect. We studied chick behavior and survival using radio telemetry and direct observation and found that vehicles caused mortality and affected behavior and resource use by oystercatcher chicks. We identified the source of mortality for 37 radio-tagged chicks. Six (16%) were killed by vehicles, 21 (57%) by predators, and 10 (27%) by exposure and starvation. From 1995 to 2008, 25 additional oystercatcher chicks were found dead, 13 (52%) killed by vehicles. Chicks on beaches closed to vehicles used beach and intertidal zones more frequently than chicks on beaches open to vehicles. Chick predators included Great Horned Owls Bubo virginianus, Fish Crows Corvus ossifragus, cats Felis catus, mink Mustela vison, raccoons Procyon lotor, and ghost crabs Ocypode albicans. The factors affecting reproductive success differed between the incubation and chick-rearing stages. Management actions that influence chick survival will have a larger effect on total productivity than actions affecting nest survival.

North Carolina↗
USGS2016

Occurrence, morphometrics, and plumage variability among Leach’s Storm-Petrels Oceanodroma leucorhoa in the California Channel Islands, 1976–2015

We mist-netted and examined Leach’s Storm-Petrels Oceanodroma leucorhoa (LESP) caught during 1991–2015 at three locations in the California Channel Islands (CCI): Prince Island, Santa Barbara-Sutil islands and Scorpion Rock. Although mist-netting methods and effort varied between two study periods (1991–1995, 2004–2007 and 2015), during 750 h effort we captured 41 LESP during April–August, with two of these recaptured after initial banding. The majority (78%) were classified as likely breeders based on a well-developed incubation patch. We summarize island-specific efforts, capture rates and morphological measurements made at these three CCI locations. Captured LESP displayed a multimodal distribution in the overall degree of white rump plumage, with 28% classified as mostly “dark-rumped.” The majority of LESP (72%) captured in the CCI have variable white rumps, similar to what has been reported for northern California and the Farallon Islands. However, the relative proportions of “dark-rumped” individuals captured in the northern CCI is intermediate, within the shift starting at the Farallon Islands and increasing in prevalence toward the San Benito Islands, Baja California. More remains to be learned about LESP in the CCI, for which additional mist-netting efforts are needed, using a standardized approach that targets LESP.

California↗
USGS2016

Ashy Storm-Petrel Oceanodroma homochroa mist-netting and capture rates in the California Channel Islands, 2004–2007

The California Channel Islands (CCI) provide essential nesting habitat for a significant portion of the world’s Ashy Storm-Petrel Oceanodroma homochroa (ASSP) breeding population, but true abundance at this locality is not well known. Land-based nocturnal mistnetting has been conducted sporadically in the CCI since 1976, with variation in techniques and methods. Using a standardized catch-perunit-effort (CPUE) is one of the few methods available to monitor trends in relative abundance, but there currently are no guidelines for a standardized, repeatable approach for the CCI. During 2004–2007, I conducted mist-netting for ASSP at three colony sites within the CCI: Scorpion Rock (SR), Santa Barbara Island (SBI), and Prince Island (PI). During 47 site-nights (22 sessions), I obtained 1 177 unique captures, including 34 recaptures (2.9%) of previously banded individuals. ASSP captured at all three islands showed peak proportions of fully developed incubation patches in July and August. ASSP captured in the CCI had 5%–9% lower body mass than individuals captured off central California during the early 1970s; it is not known whether this difference reflects natural inter-annual variation or differences in body condition. ASSP from SBI had the lowest body condition index (BCI) compared with those from PI and SR, indicating different foraging environments. Overall, 22 netting-sessions at three islands yielded a power of 84% to detect a 30% lesser CPUE; 19 sessions would be required in a future effort to evaluate this level of change. Evaluation of additional factors that affect CPUE and other independent measures of abundance or attendance should be included in future mist-netting efforts.

California↗
USGS2007

Birds of the Rio Grande and other riparian habitats of Western Webb County, Texas

We conducted 164 diurnal morning point counts in 1997 and 89 nocturnal point counts in 1998 along the Rio Grande and at other riparian habitats on remote ranchland in northwestern Webb County. We subsequently conducted 94 diurnal morning and 37 nocturnal point counts in 1999 on public lands along the Rio Grande and at other riparian habitats at Laredo, Webb County. From these systematic surveys (n  384) and other irregular visits to sites during the length of the study, we detected a total of 209 bird species. Many species (97) are distributed widely over much of North America, but substantial numbers of species were also of primarily eastern (30), western (30), southwestern (26), and tropical (26) distributions. Fifty-five of the 209 species (26%) occur on >1 species priority lists in six bird conservation plans that we reviewed, but only four of these were tropical species. This suggests that tropical species, the driving force behind ecotourism-sustained economies in southern Texas, may not benefit directly from recent bird conservation plans, since their lists of priority species do not include many tropical birds. Thus, conservation projects designed to benefit primarily tropical species will not be ranked highly for funding if evaluated on the basis of the bird conservation plans we reviewed.

Bulletin of the Texas Ornithological Society↗
USGS1997

Evidence of Newell's Shearwater breeding in Puna District, Hawaii

Nocturnal surveys using auditory cues and night-vision equipment were conducted during the seabird breeding season in 1993 to determine use of inland areas in the Puna District, Hawaii by Newell's Shearwater ( Puffinus auricularus newelli ). Two hundred sixty Newell's Shearwater auditory or visual detections were made during 275 survey hours from 23 Jul. 1993 - 20 Sep. 1993. Mean detection rates were 1.26 birds/h at Puulena Crater ( n = 160 Newell's Shearwater detections), 1.05 birds/h at Heiheiahulu ( n = 99) and 0.04 birds/ h at Puu Kaliu ( n = 2). Vocalizing peaked between 50 and 90 min after sunset and 4 h before sunrise. Although night-vision equipment was used on most of the seabird surveys, only 4% of seabirds were detected visually. Two road-killed birds collected in Puna in June 1993, and four burrows located in Puulena Crater after the 1994 breeding season, provided additional evidence of breeding.

Hawaii↗
USGS1998

Nest relocation using PVC "spotters"

A simple device to aid in the rapid relocation of nests, composed on PVC pipe and tie wire, is described. A 16-18 cm length of pipe can be attached to a supporting structure with a section of wire and adjusted to point at the target nest by its discoverer. Used like an lensless spotting scope, the “spotter” allows other observers to quickly and reliably relocate the nest with minimal written or verbal description.

Journal of Field Ornithology↗
USGS1983

The fledging of common and thick-billed murres on Middleton Island, Alaska

Three species of alcids, Common and Thick-billed murres ( Uria aalge and U. lomvia ) and the Razorbill ( Alca torda ), have post-hatching developmental patterns intermediate to precocial and semi-precocial modes (Sealy 1973). The young leave their cliff nest sites at about one quarter of adult weight and complete their growth at sea. At departure, an event here loosely referred to as "fledging," neither primary nor secondary flight feathers are grown, but well-developed wing coverts enable limited, descending flight.

Alaska↗
USGS1988

Factors influencing predation associated with visits to artificial goose nests

Artificial goose nests were used to determine what factors might increase predation after visits to nests of Cackling Canada Geese ( Branta canadensis minima ). We tested whether leaving the nest uncovered, marking the nest location with a flag, or placing the nest on an island or peninsula would increase the rate of predation. Predators destroyed significantly more of the nests with eggs exposed to view (61%) than of the nests with eggs covered with goose down (35%) (P < 0.05). However, the rate of predation was only slightly higher among nests located on peninsulas than on islands and equal proportions of flagged and unflagged nests were destroyed. We also determined that investigators attracted predators to the study area and caused an increase in predation at uncovered nests immediately after the visit. Covering the eggs with down essentially negated the effect of attracting predators when visiting the nest. Among the 46 nests destroyed, 78% were destroyed by birds and 22% by mammals. Results of our study suggested that visibility of exposed eggs rather than nest markers provided important cues to avian predators and that islands probably provided some refuge from mammalian predators. Investigators can take steps to minimize their impact on nesting success and should incorporate a measure of that impact in their studies.

Alaska↗
USGS1992

Breeding chronology of mottled ducks in a Texas coastal marsh

The relationship between breeding chronology of Mottled Ducks ( Anas fulvigula fulvigula ) and wetland conditions at San Bernard National Wildlife Refuge was examined over a 3-yr period. Median nest initiation dates varied by as much as 68 d among years. Initiation occurred earlier in 1985 and 1987 versus 1986 (P < 0.05). Nesting initiation was not associated with winter and spring temperatures, but late nesting occurred in 1986 following low rainfall during fall and winter. Low rainfall caused low water levels in all marsh types. Water levels and wetland availability may influence nesting dates by limiting the food resources available to prenesting and nesting Mottled Ducks.

Texas↗
USGS1992

Intraspecific variation in egg shape among individual emperor geese

Within-clutch variability in shape of 1743 eggs from 301 nests of Emperor Geese ( Chen canagicus ) laid over a 5-yr period was measured. Individual females laid similar shaped eggs in successive years, and eggs among clutches within females could not be distinguished. Cluster analysis correctly identified 69.9% of 136 known conspecific parasitic eggs. Repeatability estimates of elongation (0.73), sphericity (0.72), maximum width (0.69) and radius of the point (0.68) were high and similar to repeatability estimates of egg mass and volume of other species. Although width, volume and area measurements varied inversely with spring population size, shape variables did not. The consistency in shape variables despite changes in egg size suggests that shape variables may be used to separate and identify individuals within and among years despite changes in the population that may result in changes in egg size. Differences in egg shape among eggs within a nest are viable criteria for identifying parasitic eggs, especially when used in conjunction with other methods.

Journal of Field Ornithology↗
USGS1994

Blood sampling in juvenile buff-breasted sandpipers: Movement, weight change and survival

The effect of blood sampling on juvenile Buff-breasted Sandpipers ( Tryngites subruficollis ) was evaluated by comparing movements, mass, and survival of 10 broods (37 chicks) that were bled and eight broods (31 chicks) that were not bled. Blood was sampled from the jugular vein of chicks when they weighed 9.1 ± 0.9 g (x̄ ± SD) on or within 1 d of hatch. Chicks showed few short-term negative effects from blood sampling. Individual chicks suffered little physical injury, and five of eight chicks where injury occurred (i.e., hematomas formed) survived to fledging. Furthermore, bled broods gained mass at a comparable rate during the first 5 d post-hatch, and were resighted at similar frequencies as broods that were not bled. Bled broods moved slightly longer distances than control broods 1 d after hatch, however. This increased activity may have been stress-induced, but was only temporary; bled and control broods made similar long-term movements, and the probability of resighting was similar at fledging. With the proper precautions, it appears that Buff-breasted Sandpiper young can be safely sampled for blood at an early age without causing undue harm.

Alaska↗