Seasonal abundance of nonbreeding Piping Plovers on a Georgia barrier island

ABSTRACT.   Although breeding populations of Piping Plovers are well studied, their winter distribution is less clear. We studied the seasonal abundance of nonbreeding Piping Plovers ( Charadrius melodus ) during the winters of 2003–2004 and 2004–2005 on Little St. Simons Island (LSSI), Georgia. Our objectives were to determine the relative abundance of individuals from three breeding populations at LSSI, and identify possible differences among populations in arrival time, winter movements, or departure time. We observed up to 100 Piping Plovers during peak migration, and approximately 40 plovers wintered at LSSI. From July 2004 to May 2005, approximately 20% of the Great Lakes breeding population used LSSI. Plovers were not present at LSSI during June. All breeding populations of Piping Plovers had similar patterns of temporal occurrence on LSSI, suggesting no need for population-specific management plans at this site. Our results suggest that LSSI is among the most important wintering sites on the Atlantic coast for Piping Plovers, especially for individuals from the endangered Great Lakes population.     

Survival and site fidelity of Piping Plovers on Long Island, New York

ABSTRACT.   The threatened Atlantic Coast population of Piping Plovers ( Charadrius melodus ) has not increased in recent years and remains 332 pairs short of the recovery goal of 2000 pairs. Habitat loss to development is a major threat to the population, and there has been interest in restoring nesting and foraging habitat. However, the demographic response of coastal Piping Plovers to either habitat loss or creation has not been documented. We estimated survival rates and site fidelity of a declining Piping Plover population on Long Island, New York, from 2001 to 2005 on a beach subject to human development and recreation. The mean annual adult survival was 0.703 ± 0.032 (SE) and was similar among years. Site fidelity during the period of territory establishment averaged 0.827 ± 0.069 (SE). Given this high site fidelity, ensuring the survival of adults is important for maintaining local populations. Although the 2002–2004 average was high, site fidelity was apparently lower in 2003 than in 2002. This decrease in site fidelity may have been related to several years of habitat loss and increasing predation of nests or chicks, as reported in a partly concurrent long-term study at our site. The species-level effect of local dispersal due to anthropogenic habitat loss depends on the fitness of dispersers, and is currently unknown for Piping Plovers.     

Nest‐site selection by Interior Least Terns and Piping Plovers at managed,off‐channel sites along the Central Platte River in Nebraska,USA

Given the high productivity of Interior Least Terns (Sternula antillarum athalassos) and Piping Plovers (Charadrius melodus) on constructed off‐channel nesting sites along the central Platte River in Nebraska, USA, and the possibility of creating similar habitats at other locations in their breeding range, understanding how these species use off‐channel nesting habitats is important. We used data collected along the central Platte River in Nebraska, USA, over a 15‐year period (2001–2015), and a discrete‐choice modeling framework to assess the effects of physical site attributes and inter‐ and intraspecific associations on off‐channel nest‐site selection by Interior Least Terns and Piping Plovers. We found that Piping Plovers avoided nesting near each other, whereas colonial Interior Least Terns selected nest sites near those of conspecifics. In addition, the relative probability of use for both species was maximized when distance to the nearest predator perch was ≥ 150 m and elevation above the waterline was ≥ 3 m. Probability of use for nesting by Interior Least Terns increased as distance to water increased, whereas the probability of use by Piping Plovers was maximized when distance to water was ~50 m. Our results suggest that important features of constructed, off‐channel nesting sites for both species should include no potential predator perches within 150 m of nesting habitat and nesting areas at least 3 m above the waterline. Efficient site designs for Interior Least Terns would be circular, maximizing the area of nesting habitat away from the shoreline, whereas an effective site design for Piping Plovers would be more linear, maximizing the area of nesting habitat near the waterline. An efficient site design for both species would be lobate, incorporating centralized nesting habitat for Interior Least Terns and increased access to foraging areas for nesting and brood‐rearing Piping Plovers.     

Space use by Great Lakes Piping Plovers during the breeding season

ABSTRACT.   Identifying and protecting breeding habitat for imperiled species requires an understanding of the spatial and temporal movements of breeding individuals. During the 2003 and 2004 breeding seasons, we examined space use by Piping Plovers ( Charadrius melodus ) in the federally endangered Great Lakes population. We used coordinate geometry to estimate home range sizes of individual birds and examined relationships between home range size and breeding stage (incubation versus chick rearing), year, sex, number of locations, minimum plover age, distance to the nearest nest, and human beach use (high, medium, or low). The mean size of home ranges of Piping Plovers that fledged at least one chick was 2.9 ± 0.5 (SE) ha (range = 0.4–11.2 ha), and the mean linear beach distance traversed was 475 ± 53 m (range = 130–1435 m). Individuals used 3 times more beach area and 1.5 times more shoreline distance in 2003 than in 2004. Females used smaller areas than males overall and during chick rearing. Home ranges were smallest on beaches with low public use, suggesting that human disturbance may cause greater movement by individual plovers and that larger protected areas may be warranted on beaches frequented by the public to minimize disturbance to breeding birds. Our results demonstrate that nesting Great Lakes Piping Plovers occupy relatively small ranges and, therefore, that even relatively small areas of suitable habitat can have a high conservation value for this endangered population. However, the total area of habitat used varied substantially among individuals, and this should be considered when protecting habitat for the species.     

Band-related leg injuries in an Australian passerine and their possible causes

ABSTRACT.   We examined the extent and causes of band-related leg injuries in an Australian passerine, the Bell Miner ( Manorina melanophrys ). Eight percent of banded birds exhibited leg injuries, and most were birds with two plastic color bands on a tarsus. Leg injuries typically followed the accumulation of shed tarsal scales under the color bands. Color bands used on Bell Miners were tighter on the tarsus than the metal band and also tighter than the color bands used on Superb Fairy-wrens ( Malurus cyaneus ), a commonly banded species with no reported leg injuries. The tendency for scales to accumulate under two plastic color bands appeared to be influenced by the diameter of a band relative to the size of a bird's tarsus (with looser bands less likely to cause accumulation) and the material used to make the band (with smoother surfaces less likely to cause accumulation). Celluloid color bands had rougher internal surfaces than either Darvic or metal bands. In addition, both celluloid and Darvic color bands generated static electricity capable of attracting tarsal scales. Scales that accumulated under bands provided an environment where potentially harmful fungi became established, potentially contributing to the severity of leg injuries. Our results suggest that, when selecting an appropriate band size for a bird, the diameter of the tarsus at its midpoint should occupy only between 60% and 65% of the internal diameter of the band and, when possible, a single, bicolored, anodized aluminum alloy band should be used instead of multiple plastic color bands.     

Breeding sites and winter site fidelity of Piping Plovers wintering in The Bahamas,a previously unknown major wintering area

Most of the known wintering areas of Piping Plovers (Charadrius melodus) are along the Atlantic and Gulf coasts of the United States and into Mexico, and in the Caribbean. However, 1066 threatened/endangered Piping Plovers were recently found wintering in The Bahamas, an area not previously known to be important for the species. Although representing about 27% of the birds counted during the 2011 International Piping Plover Winter Census, the location of their breeding site(s) was unknown. Thus, our objectives were to determine the location(s) of their breeding site(s) using molecular markers and by tracking banded individuals, identify spring and fall staging sites, and examine site fidelity and survival. We captured and color‐banded 57 birds in January and February 2010 in The Bahamas. Blood samples were also collected for genetic evaluation of the likely subspecies wintering in The Bahamas. Band re‐sightings and DNA analysis revealed that at least 95% of the Piping Plovers wintering in The Bahamas originated on the Atlantic coast of the United States and Canada. Re‐sightings of birds banded in The Bahamas spanned the breeding distribution of the species along the Atlantic coast from Newfoundland to North Carolina. Site fidelity to breeding and wintering sites was high (88–100%). Spring and fall staging sites were located along the Atlantic coast of the United States, with marked birds concentrating in the Carolinas. Our estimate of true survival for the marked birds was 0.71 (95% CI: 0.61–0.80). Our results indicate that more than one third of the Piping Plover population that breeds along the Atlantic coast winters in The Bahamas. By determining the importance of The Bahamas to the Atlantic subspecies of Piping Plovers, future conservation efforts for these populations can be better focused on where they are most needed.     

Survival,site fidelity,and the population dynamics of Piping Plovers in Saskatchewan

ABSTRACT To conserve threatened species, managers require predictions about the effects of natural and anthropogenic factors on population growth that in turn require accurate estimates of survival, birth, and dispersal rates, and their correlation with natural and anthropogenic factors. For Piping Plovers (Charadrius melodus), fledging rate is often more amenable to management than adult survival, and population models can be used to estimate the productivity (young produced per breeding female) necessary to maintain or increase populations for given levels of survival. We estimated true survival and site fidelity of adult and subadult (from fledging to second year) Piping Plovers breeding in Saskatchewan using mark‐resight data from 2002 to 2009. By estimating true survival rather than apparent survival (which is confounded with permanent emigration), we were able to provide more accurate projections of population trends. Average adult and subadult survival rates during our study were 0.80 and 0.57, respectively. Adult survival declined over time, possibly due in part to the loss of one breeding site to flooding. Average adult and subadult site fidelity were 0.86 and 0.46, respectively. Adult site fidelity declined during our study at two study sites, most strongly at the flooded site. Male and female Piping Plovers had similar survival rates, but males had greater site fidelity than females in some years. Based on our survival estimates, productivity needed for a stationary population was 0.75, a benchmark used for plover management on the Atlantic Coast, but not previously estimated for Prairie Canada. In stochastic simulations incorporating literature‐based variation in survival rates, productivity needed for a stationary population increased to 0.86, still lower than that previously estimated for western populations. Mean productivity for our study sites ranged from 0.87 to 0.96 fledged young per pair. Our results suggest that fledging rates of Piping Plovers in Saskatchewan were sufficient to ensure a stationary or increasing population during our study period. However, large‐scale habitat changes such as drought or anthropogenic flooding may lead to dispersal of breeding adults and possibly mortality that will increase the fledging rate needed for a stationary population.     

Field‐readable alphanumeric flags are valuable markers for shorebirds: use of double‐marking to identify cases of misidentification

Implicit assumptions for most mark‐recapture studies are that individuals do not lose their markers and all observed markers are correctly recorded. If these assumptions are violated, e.g., due to loss or extreme wear of markers, estimates of population size and vital rates will be biased. Double‐marking experiments have been widely used to estimate rates of marker loss and adjust for associated bias, and we extended this approach to estimate rates of recording errors. We double‐marked 309 Piping Plovers (Charadrius melodus) with unique combinations of color bands and alphanumeric flags and used multi‐state mark recapture models to estimate the frequency with which plovers were misidentified. Observers were twice as likely to read and report an invalid color‐band combination (2.4% of the time) as an invalid alphanumeric code (1.0%). Observers failed to read matching band combinations or alphanumeric flag codes 4.5% of the time. Unlike previous band resighting studies, use of two resightable markers allowed us to identify when resighting errors resulted in reports of combinations or codes that were valid, but still incorrect; our results suggest this may be a largely unappreciated problem in mark‐resight studies. Field‐readable alphanumeric flags offer a promising auxiliary marker for identifying and potentially adjusting for false‐positive resighting errors that may otherwise bias demographic estimates.     

Colored plastic and metal leg bands do not affect survival of Piping Plover chicks

ABSTRACT Leg bands are commonly used to mark shorebird chicks as young as 1‐d old, but little is known about the possible impacts of bands on survival of prefledging shorebirds. We used a mark‐recapture framework to assess the impact of bands and banding‐related disturbance on prefledging survival in a federally endangered population of Piping Plovers (Charadrius melodus) breeding in the Great Lakes region from 2000 to 2008. We banded approximately 96% of all surviving chicks hatched prior to fledging, typically between 5 and 15 d of age. We used a multistate approach in program MARK whereby individuals contributed data as unbanded chicks before capture (N= 1073) and as banded chicks afterward (N= 780). The cumulative probability of surviving through 24 d of age was 0.63 and did not differ between banded and unbanded chicks. In addition, we found a positive effect of banding‐related disturbance on survival up to 3 d following banding (β= 0.60 CI: 0.17–1.02), possibly due to increased postbanding vigilance on the part of chicks and adults. Our results indicate that banding has no detrimental effect on survival of Piping Plover chicks prior to fledging and that current capture and banding methods are appropriate for this endangered species.     

Identification and breeding of yearling Piping Plovers

ABSTRACT Age of first breeding is an important life history trait. Many Piping Plovers (Charadrius melodus) do not breed as yearlings, but little information is available concerning the age of first breeding. From 2000 to 2006, we marked 991 chicks in three areas in Saskatchewan, Canada, and subsequently determined when 102 (49 females and 53 males) first bred. Females bred significantly earlier, on average, than males. More females (68%) bred as yearlings than did males (41%; P= 0.04), with most others first nesting when 2‐yr old (29% of females and 50% of males). As expected from differences between the sexes in age of first breeding, younger females were more likely to pair with older males than were younger males with older females. Chicks that hatched early in the breeding season did not breed at an earlier age than those that hatched late in the year. Unlike older birds, juvenile Piping Plovers do not replace flight feathers during their first winter. As a result, 18 of 27 yearlings (67%) had worn outer primaries, whereas only one of 123 (1%) older birds had worn primaries. In addition, whereas 20 of 24 yearlings (83%) retained a few buff‐tipped median coverts, none of 119 known older birds had such coverts. As a result, we were able to identify all yearlings by their worn primaries, buff‐tipped median wing coverts, or both. Wing lengths of yearling Piping Plovers were 3% shorter than those of older birds, presumably due to wear. Because there is no evidence of differences in adult survival rates between the sexes and breeding habitat is available, we speculate that fewer yearling males than females breed because primary wear may reduce the ability of yearling males to perform aerial breeding displays.     

Loss of Butt-End Leg Bands on Male Wild Turkeys

ABSTRACT We estimated loss of butt-end leg bands on male wild turkeys (Meleagris gallapavo) captured in New York, Ohio, and Pennsylvania (USA) during December-March, 2006–2008. We used aluminum rivet leg bands as permanent marks to estimate loss of regular aluminum, enameled aluminum, anodized aluminum, and stainless steel butt-end leg bands placed below the spur. We used band loss information from 887 turkeys recovered between 31 days and 570 days after release (x̄ = 202 days). Band loss was greater for turkeys banded as adults (>1 yr old) than juveniles and was greater for aluminum than stainless steel bands. We estimated band retention was 79–96%, depending on age at banding and type of band, for turkeys recovered 3 months after release. Band retention was <50% for all age classes and band types 15 months after banding. We concluded that use of butt-end leg bands on male wild turkeys is inappropriate for use in mark-recapture studies.     

Piping Plovers make decisions regarding dispersal based on personal and public information in a variable coastal ecosystem

ABSTRACT An increasing number of studies have revealed that public information influences dispersal decisions in a wide variety of species. However, few empirical studies have explored the effect of environmental predictability on the use of public information. We applied a model‐selection approach to data gathered from 1998 to 2006 in five eastern Canada provinces to determine the factors influencing breeding dispersal distances of Piping Plovers (Charadrius melodus melodus), a species that encounters substantial interannual changes in habitat quality. We examined the following hypotheses: (1) individuals that are unsuccessful breeders disperse greater distances than individuals that breed successfully and (2) dispersal distances of failed breeders are negatively correlated with the reproductive success of locally breeding conspecifics. We found that mean dispersal distance was greater for plovers that did not breed successfully the previous year (x′= 17.8 ± 27.4 [SD] km, N= 15) than for those that were successful (x′= 5.8 ± 26.4 km, N= 71). Failed breeders whose neighbors produced no fledged young dispersed over distances 34.8 times greater than those whose neighbors produced four fledglings. Our results show that public information is used in habitats whose environmental predictability is lower than predicted by theoretical studies. Thus, dispersal appears to be triggered by a combination of failure to hatch at least one egg, and the failure of neighboring pairs to produce fledglings. Individuals therefore appear to preferentially return to sites where breeding success is high. This may partly explain why Piping Plovers use only a fraction of the suitable breeding habitat within their geographic range. Consequently, although suitable habitat is present elsewhere within the breeding range, the loss of traditional nesting sites is likely to significantly impact productivity of this endangered species.     

Accuracy of nest fate classification and predator identification from evidence at nests of Least Terns and Piping Plovers

For federally listed species such as Least Tern Sternula antillarum and Piping Plover Charadrius melodus, correct determination of nest fates and causes of nest failure is crucial for understanding population dynamics and improving monitoring programmes. We used video cameras to evaluate nest fate misclassification rate and to identify factors that may cause researchers monitoring nests at different intervals to classify Least Tern and Piping Plover nest fates incorrectly. During the 2013–2015 breeding seasons, we installed miniature surveillance cameras at 65 of 294 Least Tern and 89 of 551 Piping Plover nests under observation on the Missouri River in North Dakota. Nest fates were assigned in the field from remains found at the nest‐site and then again by an independent researcher who reviewed camera footage. We used ordinal logistic regressions to examine whether monitoring interval, clutch age or temporal factors influenced a correct, partially misclassified (probable successful in the field vs. successful by camera) or misclassified nest fate classification. During a 7‐day monitoring interval between visits, 45% of nests were partially and 27.5% were fully misclassified. The percentage of partially (20%) and fully (8.0%) misclassified nests decreased with a more intensive (3‐day) monitoring schedule. Researchers were also less likely to correctly classify nest fates for Least Terns than for Piping Plovers, and as clutch age and monitoring interval increased for both species. Furthermore, causes of failure (e.g. predators, weather) as determined from field evidence vs. video disagreed for 53.5% of nests. The ability to identify accurately nest fate and cause of nest failure will facilitate a better understanding of factors that limit productivity and will lead to better informed management decisions for improving nest survival.     

Abundance of Snowy and Wilson's Plovers in the lower Laguna Madre region of Texas

ABSTRACT.   Snowy Plovers ( Charadrius alexandrinus ) and Wilson's Plovers ( C. wilsonia ) are shorebird species of increasing conservation concern, with populations apparently declining in North America. However, estimates of current populations are needed before initiating long-term monitoring or planning. In 2004, we estimated abundance of breeding Snowy and Wilson's plovers in the lower Laguna Madre region of Texas using occupancy abundance estimation. We made repeated visits to survey plots from April to June, recording the number of adults of both species observed and the amount of suitable breeding habitat within each plot. We considered Bayesian occupancy abundance models with and without habitat covariates to explain the abundance of both species. For both Snowy and Wilson's plovers, the number of birds counted in each plot was influenced by the amount of suitable breeding habitat within the plot (Snowy Plover α_habitat= 0.52, SD = 0.10, 95% CI = 0.33–0.71; Wilson's Plover α_habitat= 0.48, SD = 0.12, 95% CI = 0.24–0.71). Using the habitat covariate models for each species, we estimated that 416 adult Snowy Plovers (95% CI = 394–438) and 279 adult Wilson's Plovers (95% CI = 262–296) were present in our study area. Our results illustrate the use of a relatively new method for abundance estimation, and indicate that the lower Laguna Madre region of Texas is an important breeding area for both Snowy and Wilson's plovers. Given the documented and suspected population declines for Snowy and Wilson's plovers, we recommend protection of their breeding habitats along the coast of Texas from development and degradation resulting from unregulated use.     

Plasticity of Least Tern and Piping Plover nesting behaviors in response to sand temperature

Birds that nest on the ground in open areas, such as Piping Plovers (Charadrius melodus) and Interior Least Terns (Sternula antillarum athalassos), are exposed to high temperatures in thermally stressful environments. As a result, some ground-nesting avian species have adapted behavioral strategies to maintain thermal regulation of eggs and themselves. We assessed the impact of sand temperature on shorebird nesting behaviors by installing video cameras and thermocouples at 52 Least Tern and 55 Piping Plover nests on the Missouri River in North Dakota during the 2014–2015 breeding seasons. Daily duration and frequency of shading behaviors exhibited a nonlinear relationship with temperature; therefore, we used segmented regressions to determine at what threshold temperature (mean temperature = 25.7^⸰C for shading behavior daily frequency and mean temperature = 25.1^⸰C for shading behavior daily duration) shorebird adults exhibited a behavioral response to rising sand temperatures. Daily nest attendance of both species decreased with increasing sand temperatures in our system. Frequency and duration of daily shading behaviors were positively correlated with sand temperatures above the temperature threshold. Piping Plovers exhibited more and longer shading behaviors above and below the temperature thresholds (below: frequency = 10.30 ± 1.69 se, duration = 7.29 min ± 2.35 se; above: frequency = 59.27 ± 6.87 se) compared to Least Terns (below: frequency = −1.37 ± 1.98 se, duration = −0.73 min ± 1.51 se; above: frequency = 31.32 ± 7.29 se). The effects of sand temperature on avian ground-nesting behavior will be critical to understand in order to adapt or develop recovery plans in response to climate change.     

Variation in the use of pasture by breeding European Golden Plovers Pluvialis apricaria in relation to prey availability

European Golden Plover Pluvialis apricaria populations have declined across Western Europe. Changes to upland grasslands that are utilized by foraging off-duty birds may have contributed to this decline. The use of enclosed agricultural land by a stable breeding population of Golden Plovers in the South Pennines is described to examine this hypothesis. Fields contained foraging plovers from the end of February to the end of July. Off-duty incubating birds commuted to feed on fields, females during the day and males at night. During the day, adults flew from 6.6 to 7.2 km from the nest to feed, whilst at night birds commuted from 2.4 to 2.7 km. The length of time spent foraging by males was inversely dependent upon daylength. Following hatching, the use of pasture declined, although not as much as in other studies. Arable and improved fields received most use by 15 radiotagged birds, whilst the use of pasture throughout the breeding season was negatively correlated with sward height. Adult diet consisted largely of subsurface prey, particularly larval tipulids, although earthworms were an important component in March and April. The biomass of larval tipulids was strongly correlated with an index of the use of fields. The selection of fields by Golden Plovers is therefore dependent upon prey abundance and availability, and, consequently, is likely to be enhanced by summer grazing and poor drainage. These findings are discussed in the light of recent trends in pastoral management.     

The functions of belly-soaking in Kentish Plovers Charadrius alexandrinus

We tested whether belly-soaking (i.e. wetting of ventral plumage) in incubating Kentish Plovers Charadrius alexandrinus in a hot environment serves to cool overheated eggs, or whether belly-soaking would mainly serve for adult thermoregulation, and egg wetting would be a mere consequence of the ventral feathers of incubating adults being wet. When ambient temperature was high (> 30 °C), body temperature of incubating Kentish Plovers increased with ambient temperatures. When adults departed from nests to belly-soak, egg temperatures were not critical for embryos. However, eggs in exposed nests overheated to levels that may be lethal for embryos when adults left the nests to belly-soak, and adults also employed belly-soaking to cool down overheated eggs when they returned to their nests. Indeed, the cooling rate of eggs was much faster when they were wetted. We conclude that the primary function of belly-soaking in the Kentish Plover is to dissipate body heat in heat-stressed incubating adults, rather than to cool overheated eggs. Eggs overheated as a consequence of short-term interruptions in nest attendance by heat-stressed adults to belly-soak, and Plovers employed secondarily belly-soaking to cool down overheated eggs. These results indicate that adult thermoregulation and egg cooling are not mutually exclusive functions of belly-soaking.     

Estimating survival of precocial chicks during the prefledging period using a catch-curve analysis and count-based age-class data

ABSTRACT.   Estimating reproductive success for birds with precocial young can be difficult because chicks leave nests soon after hatching and individuals or broods can be difficult to track. Researchers often turn to estimating survival during the prefledging period and, though effective, mark-recapture based approaches are not always feasible due to cost, time, and animal welfare concerns. Using a threatened population of Piping Plovers ( Charadrius melodus ) that breeds along the Missouri River, we present an approach for estimating chick survival during the prefledging period using long-term (1993–2005), count-based, age-class data. We used a modified catch-curve analysis, and data collected during three 5-day sampling periods near the middle of the breeding season. The approach has several ecological and statistical assumptions and our analyses were designed to minimize the probability of violating those assumptions. For example, limiting the sampling periods to only 5 days gave reasonable assurance that population size was stable during the sampling period. Annual daily survival estimates ranged from 0.825 (SD = 0.03) to 0.931 (0.02) depending on year and sampling period, with these estimates assuming constant survival during the prefledging period and no change in the age structure of the population. The average probability of survival to fledging ranged from 0.126 to 0.188. Our results are similar to other published estimates for this species in similar habitats. This method of estimating chick survival may be useful for a variety of precocial bird species when mark-recapture methods are not feasible and only count-based age class data are available.     

State uncertainty models and mark‐resight models for understanding non‐breeding site use by Piping Plovers

Conservation of beach‐nesting medium‐distance migrants has focused on breeding areas because protection of nests is more tractable than protection of non‐breeding habitat. As breeding ground management has encountered diminishing returns, interest in understanding threats in non‐breeding areas has increased. However, robust estimates of non‐breeding demographic rates and abundance are generally lacking, hindering the study of limiting factors. Estimating such rates is made more difficult by complex population dynamics at non‐breeding sites. In South Carolina, endangered Piping Plovers Charadrius melodus start arriving in July and some depart prior to December (the autumn‐only population) while others remain through at least March (the wintering population). State uncertainty capture‐mark‐recapture models provide a means for estimating vital rates for such co‐occurring populations. We estimated the proportion of the population entering the study area per survey (entry probability) and proportion remaining per survey (persistence rate) for both populations during autumn, and abundance of the wintering population, at four sites in South Carolina in 2006/7 and 2007/8, taking advantage of birds previously colour‐ringed on the breeding grounds. We made fairly precise estimates of entry and persistence rates with small sample sizes. Cumulative entry probability was ~50% by the end of July and reached 95% for both populations by October. Estimated stopover duration for birds in the autumn‐only population was 35 days in year 1 and 42 days in year 2. We estimated a wintering super‐population size of 71 ± 16 se birds in the first year and 75 ± 16 in the second. If ringing programmes on the breeding grounds continue, standardized resighting surveys in the non‐breeding period and mark‐recapture models can provide robust estimates of entry and persistence rates and abundance. Habitat protection intended to benefit non‐breeding Piping Plovers at our coastal sites should be in effect by late summer, as many birds are resident from July to the end of winter.     

Mountain Plovers in Oklahoma: distribution, abundance, and habitat use

ABSTRACT.   Mountain Plover ( Charadrius montanus ) populations are inefficiently sampled by Breeding Bird Surveys. As a result, targeted sampling of select populations of this species (with an estimated global population of 11,000–14,000 birds) can be valuable. Our objectives were to determine the breeding distribution and estimate the size of the Mountain Plover population in Oklahoma. We conducted a randomized point count survey in an area where Mountain Plovers were previously known to breed and conducted additional surveys over a larger area to better delimit the distribution. We used a removal model to estimate detection probability for raw counts obtained from 1104 point counts in 2004 and 2005, and derived a state-level population estimate using the detection-adjusted counts. Mountain Plovers used flat, bare, cultivated fields for nesting, and their distribution was closely tied to the presence of clay loam soils. We estimated that at least 68–91 Mountain Plovers bred in Oklahoma in 2004–2005. The low breeding density we observed may be due to the location of our study area near the southeastern edge of the breeding range of these plovers, the low-quality habitat provided by cultivated landscapes, or a combination of factors. Because the number of birds is small, the status of the Oklahoma population is not likely to have a large effect on the global population. However, additional information is needed to help determine if cultivated landscapes represented population sources or sinks.