共查询到20条相似文献，搜索用时 15 毫秒
1.
Stephen M. Mullin Mark A. Colwell Sean E. Mcallister Stephen J. Dinsmore 《The Journal of wildlife management》2010,74(8):1792-1798
ABSTRACT An accurate understanding of factors influencing survival and how they affect population growth are required to determine the best conservation strategies for small populations, especially near the limit of a species' range. We estimated adult and juvenile survival for a small population of the threatened western snowy plover (Charadrius alexandrinus nivosus) in coastal northern California over 7 years (2001–2007). We also evaluated population structure and growth to determine the relative importance of immigration and local recruitment. Apparent survival for adult males (φ = 0.61 ± 0.08) was greater than that of adult females (φ = 0.50 ± 0.11), and survival of adults was greater than for juveniles (φ = 0.40 ± 0.06). An algebraic assessment of population growth (Λ) revealed that fecundity and survival were insufficient to maintain the population (Λ = 0.66–0.77), whereas estimates based on consecutive annual counts (Λ = 0.96 ± 0.26) and a Pradel model (Λ = 0.92 ± 0.11) suggested the population was more stable. These results, combined with annual variation in the number of newly marked plovers, indicate that the local population was maintained by immigration and can be classified as a sink. Management actions aimed at increasing fecundity, including predator control and greater restrictions on human activity, may be necessary to maintain this population; actions aimed at increasing adult survival are more challenging. 相似文献
2.
Brood sex ratio in the Kentish plover 总被引：3，自引：0，他引：3
Szekely Tamas; Cuthill Innes C.; Yezerinac Stephen; Griffiths Richard; Kis Janos 《Behavioral ecology》2004,15(1):58-62
How and why do the mating opportunities of males and femalesdiffer in natural population of animals? Previously we showedthat females have higher mating opportunities than males inthe Kentish plover Charadrius alexandrinus. Both parents incubatethe eggs, and males provide more brood care than females; thusit is not obvious why the females find new mates sooner thanthe males. In this study we investigated whether the sex-biasedmating opportunities stem from biased offspring sex ratios.We determined the sex of newly hatched, precocial chicks usingCHD gene markers. Among fully sexed broods, 0.461 ± 0.024(SE) of chicks (454 chicks in 158 broods) were male, and thissex ratio was not significantly different from unity. The proportionof males at hatching decreased significantly over the breedingseason, which occurred consistently in all 3 years of the study.Large chicks were more likely to be males than females. Neitherparental age nor body size of male and female parents was relatedto brood sex ratio. We also sexed a number of chicks that werecaught after they left their nest (range of estimated ages 0–17days) and found that the proportion of males increased withbrood age. This relationship remained highly significant whencontrolling statistically for hatching date. As brood size decreaseddue to mortality after the chicks left their nest, these resultssuggest that the mortality of daughters was higher than thatof the sons shortly after hatching. Taken together, our resultsshow that the female-biased mating opportunities in the Kentishplover are not due to biased brood sex ratio at hatching but,at least in part, are due to female-biased chick mortality soonafter hatching. 相似文献
3.
Brood desertion in Kentish plover: the value of parental care 总被引：2，自引：1，他引：2
To understand the evolution of parental care, one needs to estimatethe
payoffs from providing care for the offspring and from terminatingcare and
deserting them. In this study we estimated the payofffrom care provision, and
in a companion paper we analyze thepayoff from offspring desertion. In the
current study we experimentallyinvestigated the influence of the number and
sex of attendingparents on growth and survival of offspring in the Kentish
ploverCharadrius alexandrinus, in two sites (A and B). Either the
maleor the female parent was removed from some broods at hatchingof the
chicks (female-only and male-only broods, respectively),whereas in control
broods both parents were allowed to attendtheir young. At site A survival of
the chicks was lower in uniparental(male-only and female-only) broods than in
control broods, whereaswe found no difference in brood survival at site B.
Brood survivaldecreased over the season. Removal of either parent did not
influencethe growth of the young, although growth varied over the breeding
season,and it was significantly different between the sites. Theseresults
suggest that the payoff from parental care decreasesover the breeding season
and that the value of parental care(i.e., the contribution of parents to the
survival of theiryoung) may depend on the environment. 相似文献
4.
5.
Mark A. Colwell Noah S. Burrell Michael A. Hardy Kimiko Kayano Jordan J. Muir Wendy J. Pearson Sara A. Peterson Kristin A. Sesser 《Journal of Field Ornithology》2010,81(4):349-360
ABSTRACT Habitat quality, as indexed by the reproductive success of individuals, can greatly influence population growth, especially for rare species near the limits of their range. Along the Pacific coast, the Snowy Plover (Charadrius alexandrinus nivosus) is a threatened species that, in recent years, has been breeding on both riverine gravel bars and ocean beaches in northern California. From 2001 to 2009, we compared the habitat characteristics, breeding phenology, reproductive success, and abundance of Western Snowy Plovers occupying these two habitats. Similar percentages of yearling and adult plovers returned to gravel bars and beaches, but plovers breeding on gravel bars arrived and initiated first clutches 2–3 weeks later than those breeding on beaches. Despite this delay, however, the mean annual fledging success of plovers on gravel bars (1.4 ± 0.4 [SD]) was double that on beaches (0.7 ± 0.3). Differences in cumulative reproductive success produced a stronger pattern. By their sixth year, males on gravel bars had fledged 14.5 ± 2.1 chicks, more than four times the number of young fledged by males on beaches (3.3 ± 3.1). Over 9 years, local population size decreased by about 75%, coincident with a shift in breeding distribution away from high‐quality gravel bars to ocean beaches. This unexpected population decline and shift to poorer quality beaches may have been related to occasional low survival of plovers that over‐winter exclusively on beaches in our study area. Consistently low productivity of plovers breeding on ocean beaches suggests the need for intensified management to ameliorate the negative impacts of predation and human activity on the recovery of this population. 相似文献
6.
Abstract: Wetlands in the Playa Lakes Region (PLR) provide important habitats for wintering waterfowl, cranes, and both migrant and breeding shorebirds. Playa Lakes Region wetlands experience naturally fluctuating hydroperiods but are exposed to anthropogenic stresses, which are exacerbated during summer and may influence PLR wetland occupancy and selection by breeding shorebirds. We examined wetland-scale habitat use and nest-site selection of the 4 dominant shorebirds (American avocets [Recurvirostra americana], black-necked stilts [Himantopus mexicanus], killdeer [Charadrius vociferus], snowy plovers [C. alexandrinus]) nesting in playas, saline lakes, and in both created and riparian wetlands in the PLR of Texas, USA. All 4 species nested in saline lakes. Only avocets and killdeer nested in playas, and snowy plovers nested in riparian wetlands. No nests were found in created wetlands. Wetland habitat changed (P < 0.001) during the breeding season, while water habitats generally decreased. Used (i.e., shorebirds found nesting) wetlands had more (P < 0.05) mudflats than non-used (i.e., shorebirds not found nesting) wetlands, which had more (P < 0.05) dry habitats. Used and non-used wetlands had similar (P > 0.05) amounts of water habitats. Nests were located close to vegetation on bare dry ground and dry ground with vegetation. Because water is ephemeral in PLR wetlands, shorebirds must select—in a somewhat predictive manner upon arrival—wetlands with suitable nest-site and brood-rearing habitat. Although surface water is necessary for nesting, its presence is not adequate for delineating suitable PLR wetland habitat for breeding shorebirds. Our findings that created wetlands cannot compensate for regional wetland losses in habitat or function highlights the need for conservation of natural PLR wetlands 相似文献
7.
To understand the evolution of parental care, one needs to estimatethe
payoffs from providing care for the offspring and the payoffsfrom terminating
care and deserting them. These payoffs arerarely known. In this study we
experimentally estimated therewards from brood desertion in a species that
has a variablepattern of parental care. In particular, either the female or
themale parent may desert the brood in Kentish plover Charadrius
alexandrinus,so some broods are attended by one parent of either sex,
whereasin other broods both parents stay with the brood until the chicks
fledge.We created single males and single females by experimentallyremoving
the other parent and the clutch. The expected rematingtime of males was
significantly higher (median: 25.4 days) thanthat of the females (5.3 days,
p <.0001). The expected rematingtime tended to increase over the
breeding season in both sexes,although the increase was significant only in
females. The newnest of remated males was closer to their previous territory
(mean± SE, 46 ± 8 m) than that of the remated females(289
± 57 m, p <.001). Hatching success of new nestswas not
different between remated males and females. Our resultsdemonstrate that the
remating opportunities are different formale and female Kentish plovers and
these opportunities varyover the season. We propose that the remating
opportunitieswere influenced by the male-biased adult sex ratio and the
seasonaldecrease in the number of breeders. However, we stress thatmeasuring
remating times is a more direct measure of matingopportunities than
calculating the operational sex ratio. 相似文献
8.
Daniel H. Catlin James D. Fraser Joy H. Felio Jonathan B. Cohen 《The Journal of wildlife management》2011,75(2):305-310
Loss of breeding habitat and nest predation have contributed to the decline of many shorebird species. The United States Army Corps of Engineers (USACE) initiated a piping plover (Charadrius melodus) habitat creation and augmentation program on the Missouri River in the summer of 2004. The USACE increased unvegetated sandbar habitat by depositing dredged material (engineered sandbars) and by clearing vegetation from existing sandbars (managed sandbars). We evaluated the effects of this increase in nesting and foraging habitat on habitat selection and nest daily survival rate (DSR) of piping plovers on Lewis and Clark Lake and the Gavins Point Reach of the Missouri River from 2005 to 2007 (n = 623 nests). Piping plovers selected engineered sandbars more often than expected based on area and selected natural and managed habitats less than expected based on area. Daily survival rate on engineered sandbars was significantly higher than on natural or managed sandbars (log odds: 2.50, 95% CI: 1.05–5.94). Thus, plovers' habitat selection may have increased their nesting success. Our results suggest that habitat augmentation may stave off declines in piping plover populations limited by insufficient habitat and low nesting success. © 2011 The Wildlife Society. 相似文献
9.
Cheri Gratto-Trevor Diane Amirault-Langlais Daniel Catlin Francesca Cuthbert James Fraser Sidney Maddock Erin Roche François Shaffer 《The Journal of wildlife management》2012,76(2):348-355
Resightings of uniquely marked birds from 2001 to 2008 were used to determine winter distributions of 4 breeding populations of a species at risk, the piping plover (Charadrius melodus). Although considerable overlap exists, a distinct pattern in winter distributions was evident. Birds originating from eastern Canada wintered farthest north compared to other populations. Most individuals from the United States Great Lakes were found in South Carolina and Georgia in winter, whereas birds from eastern Canada were found primarily in North Carolina. Although the great majority of birds marked in Prairie Canada were observed wintering in Texas, particularly southern Texas, breeding plovers from the United States Great Plains were more widely distributed on the gulf coast from Florida to Texas. Very few large-scale movements of individuals in winter were reported either within or between years. This study highlights the significance of geographic regions for eastern Canada, the United States Great Lakes, the United States Great Plains, and Prairie Canada populations, and demonstrates relatively high winter site fidelity. This information will help focus conservation efforts for specific breeding populations during the winter. © 2011 The Wildlife Society. 相似文献
10.
11.
Snowy plovers (Charadrius nivosus) are a species of conservation concern throughout North America and listed as a threatened species in Kansas. Management to minimize the effects of flooding and predation were implemented at Kansas breeding sites in the 1980s to encourage reproductive success. However, the effectiveness of those strategies and the effect of other variables that may influence nest survival have not been formally assessed. We used Program MARK to model the daily survival rate (DSR) of 317 snowy plover nests with 14 habitat- and management-related covariates to identify factors that influence nest survival and examine the efficacy of current management practices. In 2005 and 2006, we monitored nests and collected habitat data at the 2 known breeding sites in Kansas, Quivira National Wildlife Refuge (NWR) and Cheyenne Bottoms Wildlife Area (WA). Overall DSR was greater at Quivira NWR in 2006 (0.954) than at Cheyenne Bottoms WA (0.917) and Quivira NWR (0.942) in 2005. We developed 88 candidate models of which 4 competing models (ΔAICc < 2) were identified. We selected the most parsimonious model (K = 14, wi = 0.23) as the remaining 3 included covariates deemed biologically uninformative. This model included the effect of study site and year on a quadratic time trend, and included covariates quantifying nest age; precipitation; the proportion of gravel, rock, and vegetation at nests; occurrence within an electric fence and within 20 m of a road; occurrence on a human-constructed nest mound; and adult capture during incubation. We found a strong positive relationship between the use of nest mounds and DSR, and a strong negative relationship between precipitation and DSR. We also found a strong positive relationship between DSR and the proportion of vegetation at nest sites, the occurrence of a nest within an electric fence, and adult capture at a nest. We noted a strong negative relationship between DSR and occurrence within 20 m of a road. However, we found that DSR was not sensitive to the proportion of vegetation at a nest, occurrence within an electric fence or within 20 m of a road, and to adult capture at a nest in light of covariates quantifying precipitation and the use of nest mounds. We found weak support for a positive relationship between DSR, nest age, and the proportion of gravel and rock at nests. Our results indicate that large rainfall events are a major source of snowy plover nest loss in Kansas that can be mitigated by the construction of nest mounds. Limited influence of environmental variables found to influence nest survival at other breeding sites suggests that threats to snowy plover nest survival are site specific and managers should assess local sources of nest loss prior to implementing management strategies to improve reproductive success. © 2012 The Wildlife Society. 相似文献
12.
Low hatching success may limit progress towards reaching productivity goals for Atlantic Coast piping plover (Charadrius melodus) recovery, despite management strategies to protect eggs from predators and decrease human disturbance of birds on nests. We measured piping plover hatching success on Eastern Long Island beaches and identified the major causes of egg failure to better understand why eggs that were otherwise intact (not depredated or destroyed by tidal flooding) failed to hatch. We documented egg and nest fates, dissected contents of unhatched eggs to determine viability, and recorded human and predator activity near a subset of plover nests on Suffolk County Parks properties. The low hatching success we recorded (0.60) in 2006 and 2007 would require higher chick survival rates than are typically observed for piping plovers to meet recovery targets for productivity. Few eggs showed signs of poor viability and overall egg hatchability was comparable to other ground nesting birds. Most egg failure was due to either depredation at unexclosed nests or nest abandonment by adults. The best predictor of nest abandonment was the maximum number of red fox tracks (Vulpes vulpes) counted on nearby transects (β = −1.16, 95% CI: −2.0 to −0.3) and we found evidence that plovers abandoned eggs in response to predation risk (e.g., a fox circling a nest exclosure). Adults from abandoned nests may have deserted eggs or been depredated. In either case, intact and viable eggs were abandoned. Nest abandonment was not related to human activity near nests, which were buffered from human disturbance by symbolic string fencing. Our results suggest that depredation and nest abandonment (e.g., desertion or death of adults) due to predator disturbance, not human disturbance or poor egg viability, contributed to the low hatching success we recorded. Active predator removal in addition to modification of predator exclosure use and design may be necessary to prevent direct (egg depredation) and indirect (nest abandonment) negative effects of predators on hatching success. © 2010 The Wildlife Society. 相似文献
13.
Sarah T. Saalfeld Warren C. Conway David A. Haukos William P. Johnson 《The Journal of wildlife management》2012,76(8):1703-1711
Snowy plover (Charadrius nivosus) populations have declined throughout their range, in part because of habitat degradation and poor nest success, making information regarding regionally specific nest site selection and spatial patterns important when considering habitat conservation and management guidelines. We determined nest site selection characteristics (n = 180) and examined spatial patterns (n = 215) of snowy plover nests in saline lakes in the Southern High Plains (SHP) of Texas. At 104 nests, we examined the influence of substrate type on nest temperatures and heat mitigation. Snowy plover nests were more likely to be found near an object, on pebble substrate, and with fewer plants than random sites. High use areas were generally located in areas with pebble substrate and on human-made or natural islands, berms, and peninsulas. Overall, nests placed on pebble substrate had lower temperatures during the day than nests placed on sand substrates. Nest placement on pebble substrate may be valuable to nesting snowy plovers, providing thermal advantages to incubating adults and depressing potentially high nest predation rates. Management guidelines for this region should emphasize the importance of addressing key elements of snowy plover nesting habitat including the presence of pebble substrate and reducing vegetation encroachment. © 2012 The Wildlife Society. 相似文献
14.
Michelle L. Stantial Jonathan B. Cohen Abigail J. Darrah Shannon Farrell Brooke Maslo 《The Journal of wildlife management》2020,84(8):1536-1547
Predation of nests and young is one of the limiting factors in the conservation of birds; understanding environmental covariates of predator distribution can assist with decisions regarding the best management strategies to reduce predation risk. The habitat of beach-nesting birds is often reshaped by storms in ways that may affect nest predation, such as by flattening vegetated dunes where mammals hunt, but human management of beaches tries to prevent the effects of storms on the landscape with unknown implications for predator distributions. Moreover, human development may affect predator distributions by subsidizing food and shelter. To determine the relationship between predator occupancy and landscape features in beach-nesting bird habitat, we repeated mammalian predator track surveys 8 times/year at 90 plots in southern New Jersey, USA, from 2015–2017. We used dynamic occupancy models to estimate the probability of use by red foxes (Vulpes vulpes) and to document changes in habitat use as related to landcover types over the avian breeding season within years. We had 373 red fox detections with years pooled. Detection probability for red foxes varied by year, and probability of use decreased as the distance to the nearest primary dune increased. We found no evidence that red fox habitat use depended on distance to human development. Our results suggest that conserving nesting habitat that includes open areas (i.e., storm overwash [whereby vegetation is scoured by tidal flooding]) may reduce predation risk because beach-nesting birds would not be forced into nesting close to dunes, which are typically used for hunting by red foxes. © 2020 The Wildlife Society. 相似文献
15.
Chelsea E. Weithman James D. Fraser Sarah M. Karpanty Daniel H. Catlin 《Journal of Field Ornithology》2020,91(2):170-188
Mobility of precocial chicks facilitates self-feeding and escape from predators, but also allows chicks to move into potentially dangerous areas. At Cape Hatteras National Seashore and Pea Island National Wildlife Refuge, North Carolina, precocial Piping Plovers (Charadrius melodus) are managed with vehicle and pedestrian exclusion buffers to reduce potential anthropogenic disturbance and mortality. From 2015 to 2018, we monitored 23 broods from hatching until fledging age (25 days), and recorded brood locations, chick behavior, and potentially disruptive predators, people, or vehicles. We estimated straight-line hourly movement rates relative to brood habitat selection, behavior, and potential disturbance stimuli, daily movement distances, and 95% minimum convex polygon home range areas of broods through the pre-fledging period. Daily brood movements , range = 0–327.3 m/d) varied by age and year. Hourly movements also varied , range = 0.04–1450.9 m/h), but were not well described by the factors we tested. Daily and hourly movements were generally shorter than current management buffer sizes, broods were always observed within protective buffers, and were rarely disturbed by human activity or possible predators. Home range sizes of broods ( increased as broods aged. Our results show that movements by plover broods can be variable and relatively unpredictable across temporal and spatial scales, but the low rate of brood disturbance suggests effective management of anthropogenic disturbance. We recommend that under current conditions, regular monitoring by managers should continue to ensure that the size and location of implemented buffers track actual brood use without exposing broods to risks from human beach users. 相似文献
16.
DANIELLE LE FER JAMES D. FRASER CASEY D. KRUSE 《The Journal of wildlife management》2008,72(3):682-687
Abstract: We tested the hypothesis that piping plover (Charadrius melodus) habitat quality and chick survival on the Missouri River, USA, were lower on a cold-water reservoir and downstream from a hypolimnetic (cold-water) release dam with diel water fluctuations (Garrison Dam) than downstream from an epilimnetic dam (Gavins Point Dam). Plovers in adjacent alkali wetlands provided an index to the maximum reproductive potential in the region. Chicks gained weight more rapidly in the alkali wetlands than on epilimnetic and hypolimnetic river reaches. Invertebrate numbers and biomass were higher in the wetlands and epilimnetic reach, but chick survival was lower on the epilimnetic reach. Thus, piping plovers adapted to a variety of prey densities, and other factors, likely predation, reduced survival rates in the epilimnetic reach. Temporal and spatial variability in site quality indices suggests the need for a regional management strategy with different strategies at each site. Managers can minimize effects of local fluctuations in resource abundance and predators by ensuring protection of or creating geographically dispersed habitat. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):682–687; 2008) 相似文献
17.
18.
Habitat restoration projects are often deemed successful based on the presence of the target species within the habitat; however, in some cases the restored habitat acts as an ecological trap and does not help to improve the reproductive success of the target species. Understanding wildlife–habitat relationships through precise measurements of animal behavior can identify critical resources that contribute to high quality habitat and improve habitat restoration practice. We evaluated the success of a restored piping plover (Charadrius melodus) breeding habitat in New Jersey, USA. We identified the major factors influencing foraging rates, compared foraging activity budgets over 3 yr at restored and natural habitats, and explored the potential of artificial tidal ponds as a viable restoration alternative. Adult foraging rates were higher in artificial pond and ephemeral pool habitats, during low tide, and after breeding activity ended. Adult foraging rates were impeded by the presence of people and vehicles within 50 m. Chick foraging rates were highest at artificial ponds and bay shores and lowest in dunes and on sand flats. Chick foraging rates were strongly hindered by the presence of corvids and the number of people within 50 m. In addition, at artificial tidal ponds, piping plovers spent more time foraging and less time engaged in defensive behaviors (vigilance, crouching, and fleeing) compared to other potential habitats. Our findings support the hypothesis that artificial tidal ponds are a valuable, perhaps superior, foraging habitat. Future beach restoration projects should include this feature to maximize habitat quality and restoration success. © 2011 The Wildlife Society. 相似文献
19.