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JONATHAN B. COHEN SARAH M. KARPANTY JAMES D. FRASER BRYAN D. WATTS BARRY R. TRUITT 《The Journal of wildlife management》2009,73(6):939-945
ABSTRACT Weekly counts of western Atlantic red knots (Calidris canutus rufa) at their Delaware Bay migration stopover site have suggested a major decline since the 1980s. We estimated red knot spring passage population size in the New Jersey Coast-Delaware Bay region (DENJ; 2004 and 2006) and Virginia (VA; 2006 and 2007), USA, by correcting weekly aerial counts for mean daily residence probability between counts in a Monte-Carlo simulation. We used daily telemetry relocations in mark-resight models to estimate mean daily residence probability. Average daily residence probability was approximately 1.0 in mid-May, 0.96–0.97 in the week of 22 May, and 0.64–0.77 after May 28 in DENJ in 2004 and 2006 and in VA in 2006. Average daily residency was approximately 0.88 in VA in 2007 from 22 May to 5 June. No birds moved from VA to DENJ in 2006 and only 2 birds (5.5%) moved in 2007. Stopover population sizes (±SE) in DENJ were 17,108 ± 1,322 in 2004 and 19,555 ± 831 in 2006, and in VA were 7,224 ± 389 in 2006 and 8,332 ± 718 in 2007, significantly greater than peak aerial counts. Years with similar peak counts had different residence probabilities; hence, adjustments for turnover should be used in the future to assess annual population changes. Our results suggest that VA can support a significant portion of this red knot subspecies during migration in at least some years. Managing red knots for recovery should entail improving our understanding of the use of other Atlantic Coast sites and protecting key coastal habitat from disturbance and development. 相似文献
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Joseph B. Buchanan James E. Lyons Lori J. Salzer Roberto Carmona Nallely Arce Gary J. Wiles Keith Brady Gerald E. Hayes Steven M. Desimone Greg Schirato Warren Michaelis 《Journal of Field Ornithology》2012,83(3):282-289
ABSTRACT Many shorebirds exhibit within‐ and among‐year site fidelity during their annual cycle. Little is known, however, about the migration ecology of Red Knots (Calidris canutus) that migrate along the Pacific Flyway and occur in Washington in numbers that exceed counts elsewhere on the flyway. At two large estuaries in coastal Washington, Grays Harbor and Willapa Bay, we searched for and recorded the locations of Red Knots (N= 547) that had been individually marked with leg flags at their wintering grounds in Baja California Sur, Mexico, during the period from October 2006 to April 2009. In 2010, we resighted 43 Red Knots at Grays Harbor and Willapa Bay that had been observed at these sites in previous years, primarily in 2009. We found a high degree of site fidelity between years, with birds observed in 2010 more likely to return to the same stopover site used in 2009 than to switch stopover sites. For knots that did not switch estuaries between years, the median nearest distance between locations where individuals were observed between years was 1.4 km at Grays Harbor and 0.6 km at Willapa Bay. Our results provide the first evidence of stopover site fidelity by Red Knots of the roselaari subspecies. Fidelity occurred at three spatial scales: coastal Washington, the two estuaries where we conducted our study, and specific mudflat areas within the estuaries. Because our study sites support high populations of bivalves, Red Knots may be returning to the same areas in subsequent years to exploit what we suspect is a predictable food resource. The abundance of Red Knots and high degree of site fidelity suggest that our study sites in Grays Harbor and Willapa Bay are important for the conservation of this species on the Pacific Flyway. 相似文献
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Eva M. A. Kok Jerry A. Hogan Theunis Piersma 《Ethology : formerly Zeitschrift fur Tierpsychologie》2020,126(7):681-693
Migratory shorebirds show highly organized seasonal cycles in physiological and morphological traits (body mass and composition, plumage, hormone levels, etc.), which in captivity is accompanied by restless behaviour at times when free-living birds would start migration. We introduce the idea that seasonally changing preference for habitat could motivate migrants to embark on migration and that this cognitive process could also guide them to seasonally appropriate places. We explored this by testing whether red knots (Calidris canutus), which also in captivity maintain marked circannual phenotypic rhythms, show evidence of seasonal change in preference for pictures of seasonally appropriate habitats. We first developed a method to verify whether red knots are able to memorize and discriminate contrasting pictures projected by LCD projectors. This was followed by two different experiments in which we tested for a seasonally changing preference for breeding or non-breeding habitat. When carried out during the pre-breeding season, the red knots are expected to prefer pictures of mudflats, their non-breeding habitat. At the start of the breeding season, they should prefer pictures of the tundra breeding habitat. We established that knots are able to distinguish and memorize projected images. We failed to demonstrate the predicted change in vision-based habitat preference, but for reasons of test design we do not interpret this as a strong rejection of the hypothesis. Instead, we suggest that experiments with greater numbers of individuals tested once, perhaps in combination with the provision of additional cues such as smells and sounds, will help the development of these ideas further. 相似文献
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Amelia J. Macdonald Paul A. Smith Christian A. Friis James E. Lyons Yves Aubry Erica Nol 《The Journal of wildlife management》2021,85(5):932-944
Many shorebirds rely on small numbers of staging sites during long annual migrations. Numerous shorebird species are declining and understanding the importance of these staging sites is important for successful conservation. We surveyed endangered rufa red knots (Calidris canutus rufa) staging in James Bay, Ontario, Canada, during southbound migration in 2017 and 2018. We used mark-resight data and count data in an integrated Bayesian analysis to quantify migration phenology, estimate passage population size, and model the age structure of the stopover population. Many adult red knots arrived in James Bay in a single wave in early August in 2017, whereas adult red knots arrived in multiple smaller waves in July and mid-August in 2018. These waves may correspond with breeding phenology where more red knots bred successfully and arrived in one large event in 2017 and the higher number of earlier arrivals in July 2018 may have been failed breeders. We included a binomial generalized linear model in the integrated analysis to estimate that 20% and 10% of staging red knots were juveniles in 2017 and 2018, respectively. In future applications, this method could provide a metric to assess breeding performance and develop our understanding of its role in population declines. Overall, we estimated that up to 23% of the estimated rufa red knot population staged in southwestern James Bay for an average of 10–12 days. The region is a key staging site for endangered red knots and could be included in conservation planning. © 2021 The Wildlife Society. 相似文献
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Sonia Altizer Andrew K. Davis 《Evolution; international journal of organic evolution》2010,64(4):1018-1028
The demands of long‐distance flight represent an important evolutionary force operating on the traits of migratory species. Monarchs are widespread butterflies known for their annual migrations in North America. We examined divergence in wing morphology among migratory monarchs from eastern and western N. America, and nonmigratory monarchs in S. Florida, Puerto Rico, Costa Rica, and Hawaii. For the three N. American populations, we also examined monarchs reared in four common environment experiments. We used image analysis to measure multiple traits including forewing area and aspect ratio; for laboratory‐reared monarchs we also quantified body area and wing loading. Results showed wild monarchs from all nonmigratory populations were smaller than those from migratory populations. Wild and captive‐reared eastern monarchs had the largest and most elongated forewings, whereas monarchs from Puerto Rico and Costa Rica had the smallest and roundest forewings. Eastern monarchs also had the largest bodies and high measures of wing loading, whereas western and S. Florida monarchs had less elongated forewings and smaller bodies. Among captive‐reared butterflies, family‐level effects provided evidence that genetic factors contributed to variation in wing traits. Collectively, these results support evolutionary responses to long‐distance flight in monarchs, with implications for the conservation of phenotypically distinct wild populations. 相似文献
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Klára J. Petrželková Hideo Hasegawa Chris C. Appleton Michael A. Huffman Colleen E. Archer Liza R. Moscovice Mwanahamissi Issa Mapua Jatinder Singh Taranjit Kaur 《American journal of primatology》2010,72(4):307-316
The release of any species into a novel environment can evoke transmission of parasites that do not normally parasitize the host as well as potentially introducing new parasites into the environment. Species introductions potentially incur such risks, yet little is currently known about the parasite fauna of introduced primate species over the long term. We describe the results of long‐term monitoring of the intestinal parasite fauna of an unprovisioned, reproducing population of chimpanzees introduced 40 years earlier (1966–1969) onto Rubondo Island in Lake Victoria, Tanzania, a non‐native habitat for chimpanzees. Two parasitological surveys (March 1997–October 1998 and October 2002–December 2005) identified Entamoeba spp. including E. coli, Iodamoeba buetschlii, Troglodytella abrassarti, Chilomastix mesnili, Trichuris sp., Anatrichosoma sp., Strongyloides spp., Strongylida fam. gen. sp., Enterobius anthropopitheci, Subulura sp., Ascarididae gen. sp., and Protospirura muricola. The parasite fauna of the Rubondo chimpanzees is similar to wild chimpanzees living in their natural habitats, but Rubondo chimpanzees have a lower prevalence of strongylids (9%, 3.8%) and a higher prevalence of E. anthropopitheci (8.6%, 17.9%) than reported elsewhere. Species prevalence was similar between our two surveys, with the exception of Strongyloides spp. being higher in the first survey. None of these species are considered to pose a serious health risk to chimpanzees, but continued monitoring of the population and surveys of the parasitic fauna of the two coinhabitant primate species and other animals, natural reservoir hosts of some of the same parasites, is important to better understand the dynamics of host–parasite ecology and potential long‐term implications for chimpanzees introduced into a new habitat. Am. J. Primatol. 72:307–316, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
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Mathot KJ van den Hout PJ Piersma T Kempenaers B Réale D Dingemanse NJ 《Ecology letters》2011,14(12):1254-1262
Theoretical work suggests that both negative frequency-dependent payoffs and state-dependent payoffs can lead to individual variation in behavioural plasticity. We investigated the roles of both frequency- and state-dependence on the occurrence of individual variation in behavioural plasticity in a series of experiments where we manipulated perceived predation danger for red knots (Calidris canutus islandica). We found individual variation in plasticity in a trait with negative frequency-dependent payoffs (vigilance), but not in a trait with positive frequency-dependent payoffs (escape flights). Furthermore, there was no correlation between the average level of vigilance under low predation danger and the magnitude of response to increased predation danger, as would be expected under state-dependence. Thus, our results provide support for the hypothesis that negative-frequency dependence favours individual variation in plasticity. However, negative-frequency dependence alone cannot explain why plasticity would be consistent within individuals, and future studies should address the factors that might favour individual consistency. 相似文献
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- Dispersal of plant seeds by ducks and other waterbirds is of great importance to the ecology of freshwater habitats. To unravel the mechanisms of waterbird‐mediated seed dispersal, numerous laboratory experiments have been conducted, but effects of seed and waterbird traits on dispersal potential have rarely been investigated under field conditions.
- Through analysis of the digestive tracts of 100 wild mallards (Anas platyrhynchos) across a winter season in the Netherlands, we assessed (i) the inter‐individual and seasonal variability of seeds in the digestive tract, (ii) the variability of digestive tract organ size and gizzard grit mass, and (iii) the potential effects of seed species traits and gut traits on the survival potential of ingested seeds.
- We found 4548 ingested seeds of at least 66 plant species from a wide range of habitats, most of which were retained in the gizzard. Nineteen species had not previously been reported from mallard diets. Individual tracts contained anywhere between 0 and 1048 seeds, of up to 14 species (median of three species). Diet composition and digestive tract size varied substantially between individuals and over the course of the winter season. As predicted from controlled feeding studies, we found that also in wild mallards, size‐dependent gut passage survival favours the dispersal of small‐seeded species. Despite the large variation in gizzard and small intestine size in this study, their effect on the dispersal potential of ingested seeds in the field remains unclear. We found no difference in dispersal potential between plants species growing in wet or dry habitats.
- This study demonstrates that wild mallards are opportunistic seed consumers with a very diverse diet as reflected by seed species composition in both the foregut and hindgut. However, we also show that serious limitations of field‐based analyses compared to controlled experiments can impede drawing conclusions about gut passage survival of seeds. The large variability in diet composition among individuals and over time indicates high endozoochorous dispersal potential for a wide range of plant species by wild mallard in aquatic and wetland, as well as surrounding terrestrial habitats.
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Luciana Barçante Mariana M. Vale Maria Alice S. Alves 《Journal of Field Ornithology》2017,88(4):321-335
Altitudinal migration is the seasonal altitudinal movement of birds from breeding areas to non‐breeding or wintering areas at different elevations. Although this type of migration is widely reported, questions remain concerning the number of species that perform altitudinal migration, possible variation among different taxa and geographic locations in the extent of altitudinal migration, and the foraging guilds of altitudinal migrants. We conducted an extensive bibliographic survey and compiled a list of altitudinal migrant birds worldwide. We characterized species in terms of their foraging guilds because the spatial distribution of food resources along altitudinal gradients is often evoked as a driver of bird altitudinal migration. We identified 1238 species of altitudinal migrants, ~10% of the ~10,000 extant species of birds. We found a strong geographic bias in publications focusing on avian altitudinal migration toward the United States and Costa Rica, and a paucity of studies in megadiverse regions such as the Afrotropical and Indomalayan realms, and areas in the Neotropics other than Costa Rica. We also found that most species of altitudinal migrants were invertivores rather than frugivores or nectarivores. This general pattern held true for all zoogeographic realms except the Neotropics, where nectarivores and frugivores predominated among altitudinal migrants. The prevalence of invertivore birds among altitudinal migrants is not unexpected because this is the most common foraging guild among birds worldwide. Overall, we found no prevalence of any specific foraging guild among altitudinal migrants across zoogeographic regions. The results of studies to date suggest that altitudinal migration by birds may be driven by a number of factors, including access to increased food resources for breeding or molting, weather conditions, and mating and nesting opportunities. However, to better understand the mechanisms underlying altitudinal migration, broadening the geographic scope of studies is paramount, with additional study of altitudinal migration especially needed in the megadiverse tropical regions of sub‐Saharan Africa, Southeast Asia, and South America. 相似文献
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Under time‐selected migration, birds should choose a strategy for outcompeting rivals over securing access to prime resources at the final destination. Thus, migration can be viewed as a race among individuals where winners are arriving first when conditions are suitable. The sprint migration hypothesis predicts that individuals shift from maximum sustained speed to a final burst of sprint to shorten the transition from migration to breeding (Alerstam, 2006). In this study, we test the hypothesis of a final sprint migration in a long‐distance Afro‐Palearctic migrant, the collared flycatcher Ficedula albicollis, during autumn and spring, and compare migration strategies between the seasons. In both seasons, collared flycatchers evidently exhibited sprint migration by increasing their overall speed over the last leg of migration after the Sahara crossing. This phenomenon was more pronounced in spring, contributing to overall faster spring migration and possibly highlighting higher importance for early arrival at the breeding grounds. In both seasons and particularly in spring, late departing individuals flew at a faster rate, partially being able to catch up with their early departing conspecifics. Differential fueling strategies may play an important role in determining migration speed, especially during the early stages of the migration, and might explain the observed differences in migration speeds between late and early departing individuals. Our findings suggest competition for early arrival at the breeding and at the nonbreeding destinations alike. Sprint migration might be an appropriate strategy to gain advantage over conspecifics and settle in prime territories as well as to cope with the increasingly earlier springs at high latitudes. 相似文献
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Wennerberg L 《Molecular ecology》2001,10(5):1111-1120
The large-scale migration of birds has been studied extensively by recoveries of ringed birds. However, there is very little ringing data from the arctic breeding grounds of waders. Here, the migration pattern of the dunlin, Calidris alpina, is studied with population genetic markers, using haplotype frequencies to estimate the breeding origin of migrating and wintering populations. Polymerase chain reaction (PCR) and restriction analysis of DNA from the mitochondrial control region was used to study the breeding origins of morphologically similar winter populations in the western Palaearctic, and to describe the population structure of the dunlin during winter. Also migrating dunlin from various stopover sites in Europe, Africa and Asia, were analysed with respect to their mitochondrial DNA (mtDNA) haplotypes. The genetic markers clearly show that the dunlin has a parallel migration system, with populations breeding in the western Palaearctic wintering mainly in the western part of the wintering range, and dunlin populations breeding further east wintering further east. The results also show that the distance between breeding and wintering area increases eastwards in this region. 相似文献
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Conspecific aggregation of waterfowl in winter is a common example of animal flocking behaviour, yet patterns of relatedness and temporal substructure in such social groups remain poorly understood even in common species. A previous study based on mark‐recapture data showed that Tufted Ducks Aythya fuligula caught on the same day were re‐caught together in subsequent winters more often than expected by chance, suggesting stable assortments of ‘socially familiar’ individuals between wintering periods. The genetic relationships within these social groups were not clear. Based on 191 individuals genotyped at 10 microsatellite markers, we investigated the temporal genetic structure and patterns of relatedness among wintering Tufted Ducks at Lake Sempach, Switzerland, in two consecutive winters. We found no evidence of genetic differentiation between temporal groups within or between winters. The average levels of relatedness in temporal groups were low and not higher than expected in random assortments of individuals. However, Mantel tests performed for each sex separately revealed significant negative correlations between the pairwise relatedness coefficients and the number of days between the capture dates of pairs of wintering Tufted Duck in males and females. This pattern suggests the presence of a small number of co‐migrating same‐sex sibling pairs in wintering flocks of Tufted Ducks. Our findings provide one of the first genetic analyses of a common duck species outside the breeding season and contribute to the understanding of social interactions in long‐distance migratory birds. 相似文献
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How individual birds schedule their movements and use different sites during the non‐breeding season are fundamental issues in avian migration ecology, and studies have often revealed strong seasonal variation in such strategies. Using geolocators we tracked Common Ringed Plovers Charadrius hiaticula from northern Norway to West Africa and back to assess whether there were differences in migratory speed, duration and stopover use between autumn and spring migration and whether birds used multiple sites during the non‐breeding season. Although the pace of migration was similar between autumn and spring, the length of flight bouts and duration of the preceding stopovers were positively correlated only in autumn. Four of five birds showed a marked southward movement in mid‐winter. 相似文献
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An avian equivalent of make-up? 总被引：2，自引：0，他引：2
We report that a long-distance migrating shorebird, the red knot, makes a complete switch from commonly occurring monoester preen waxes to a much rarer class of higher-molecular-weight diester waxes at the time of take-off to the high arctic breeding grounds. The cold arctic climate would have required a lowering of wax-viscosity, and thus, a shift in the reverse direction. We propose that a sexually selected need for a brilliant plumage has lead to this conter-intuitive temporary shift from monoesters to diester waxes. The difficulty of application of the diester preen waxes under cold conditions would ensure the reliability of the quality-signalling function of this most probably sexually selected trait. 相似文献
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Matthew S. Kendall John D. Christensen Zandy Hillis-Starr 《Environmental Biology of Fishes》2003,66(1):19-26
We evaluated the day-time distribution of juvenile and adult French grunts, Haemulon flavolineatum, relative to the spatial configuration of hard and soft bottom areas in a benthic landscape. Probability of juvenile presence on hard bottom sites was inversely correlated with distance to soft bottom. Adults presence at hard bottom sites showed no significant relationship with distance to soft bottom. A significant and positive relationship was found between presence of juveniles on hard bottom sites and area of soft bottom within 100m, but no significant relationship was found for area of soft bottom within 500m. Adults exhibited no significant relationship with area of soft bottom for either distance tested. These distributions are suspected to be the result of the combined influence of larval settlement patterns and foraging behaviors associated with hard and soft bottom. This study indicates that data collected at very fine scales can be analyzed in the context of the broad-scale mosaic of habitats in the benthic landscape to predict patterns of fish distribution. Such spatially explicit conclusions are not possible through analysis of fine-scale or broad-scale data alone. 相似文献
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Sarah M. Karpanty Jonathan Cohen James D. Fraser Jim Berkson 《The Journal of wildlife management》2011,75(5):984-994
Horseshoe crab (Limulus polyphemus) eggs are a dietary staple of the red knot (Calidris canutus) during its spring stopover on the Delaware Bay. Numbers of knots stopping in Delaware Bay declined in the 1990s concurrent with a decline in horseshoe crabs, leading to the hypothesis that reduced horseshoe crab egg abundance limited the red knot population. Management efforts, including a seasonal harvest moratorium in the Delaware Bay, have been instituted to restore crab populations to levels of sustainable use by multiple users, including migratory birds. Our objective was to evaluate the sufficiency of horseshoe crab eggs in Delaware Bay in May–June 2004 and 2005 for knots to refuel for their migratory flight to the Arctic breeding grounds. We examined egg counts to determine if there were fewer high egg-density sites later than earlier in the day and season, as migrating birds might deplete this resource. We studied foraging rates at red knot locations to determine if foraging probes increased with time of day and season as birds depleted surface eggs by pecking, then began probing for subsurface eggs. Finally, we experimentally tested whether red knots and their competitors depleted horseshoe crab eggs. Crab egg numbers at knot foraging sites did not decline throughout the day or season in 2004. In both years, we found no evidence that knots switched from pecking to probing with increases in time since sunrise or start of the stopover. Egg numbers were similar in exclosed and accessible plots on crab nesting depressions and in areas of open intertidal zone, but were significantly lower in accessible than in exclosed plots in the wrack line. Our results indicate that horseshoe crab eggs in Delaware Bay were sufficient to support the refueling of the present-day stopover population of red knots. If an increase in the availability of crab eggs to foraging birds does not result in an increase in knot numbers, managers must prioritize mitigation of limiting factors at other historically important spring stopovers and on the poorly understood breeding and wintering grounds in addition to the Delaware Bay. © 2011 The Wildlife Society. 相似文献
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