Condor最新文献

{"title":"Breeding success of Eleonora's Falcon in Cyprus revisited using survey techniques for cliff-nesting species","authors":"Thomas G. Hadjikyriakou, Nikolaos Kassinis, Dimitrios Skarlatos, Pantelis Charilaou, Alexander N. G. Kirschel","doi":"10.1093/condor/duaa045","DOIUrl":"https://doi.org/10.1093/condor/duaa045","url":null,"abstract":"ABSTRACT The global breeding population of Eleonora's Falcon (Falco eleonorae) is distributed from the Canary Islands in the west, across the Mediterranean Sea, to Cyprus in the east. The remoteness of nesting colonies, which are predominantly located on sea cliffs and islets, renders breeding success estimation a challenging task, requiring a composite approach to assess each of the breeding stages. Early estimates of the breeding success of Eleonora's Falcon suggested that the Akrotiri colony in Cyprus had the lowest breeding success among all the colonies throughout the species' breeding range, at a level seemingly unsustainable, suggesting the colony might have been in danger of gradual extinction. Here we use a diversity of survey methods including boat, ground, and aerial surveys, with the incorporation of photography and photogrammetry, to reassess the breeding success and the effect of nest characteristics on the Eleonora's Falcon breeding population in Cyprus. During a 6-yr study, we found that Cyprus hosts ∼138 ± 8 breeding pairs and that breeding success equals 1.54 ± 0.85 fledglings per breeding pair, and thus is considerably higher than previous estimates. In addition, by analyzing temporal variation in breeding and nest characteristics, we found that early breeding and reuse of nests positively influence breeding success, but physical nest characteristics have a limited effect on colony productivity. The range of survey methods employed, as well as the array of photography techniques utilized, enhanced the efficiency and accuracy of this study, allowing us to overcome the challenge of inaccessibility of nesting cliffs. LAY SUMMARY In this study we reassessed the breeding success and population status of Eleonora's Falcon in Cyprus, a species nesting on inaccessible sea cliffs. Low breeding success estimates from previous surveys suggested that the breeding population was unsustainable. We used ground, aerial (drone), and boat surveys, combined with photogrammetry for nesting cliff 3-D modeling, to assess breeding success and nest site suitability. Our results show that breeding success of Eleonora's Falcon is higher than previous estimates and that the population is stable. The methods employed enhanced the efficiency and accuracy of our surveys, allowing us to overcome the challenge of inaccessibility of nesting cliffs.","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa045","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44214130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Implanted satellite transmitters affect sea duck movement patterns at short and long timescales","authors":"J. Lamb, P. Paton, J. Osenkowski, S. Badzinski, A. Berlin, T. Bowman, C. Dwyer, Luke J. Fara, S. Gilliland, K. Kenow, Christine Lepage, M. Mallory, G. Olsen, M. Perry, S. Petrie, J. Savard, Lucas J. Savoy, Michael L. Schummer, Caleb S. Spiegel, S. McWilliams","doi":"10.1093/condor/duaa029","DOIUrl":"https://doi.org/10.1093/condor/duaa029","url":null,"abstract":"ABSTRACT Studies of the effects of transmitters on wildlife often focus on survival. However, sublethal behavioral changes resulting from radio-marking have the potential to affect inferences from telemetry data and may vary based on individual and environmental characteristics. We used a long-term, multi-species tracking study of sea ducks to assess behavioral patterns at multiple temporal scales following implantation of intracoelomic satellite transmitters. We applied state-space models to assess short-term behavioral patterns in 476 individuals with implanted satellite transmitters, as well as comparing breeding site attendance and migratory phenology across multiple years after capture. In the short term, our results suggest an increase in dispersive behavior immediately following capture and transmitter implantation; however, behavior returned to seasonally average patterns within ∼5 days after release. Over multiple years, we found that breeding site attendance by both males and females was depressed during the first breeding season after radio-marking relative to subsequent years, with larger relative decreases in breeding site attendance among males than females. We also found that spring and breeding migrations occurred later in the first year after radio-marking than in subsequent years. Across all behavioral effects, the severity of behavioral change often varied by species, sex, age, and capture season. We conclude that, although individuals appear to adjust relatively quickly (i.e. within 1 week) to implanted satellite transmitters, changes in breeding phenology may occur over the longer term and should be considered when analyzing and reporting telemetry data. LAY SUMMARY Implanted satellite transmitters are often used to study movements of waterfowl, but capture and implantation may also change individual behavior. Understanding these behavioral effects, and how long they last, is necessary to correctly interpret movement data from transmitters We used a set of multi-year data from sea ducks with implanted satellite transmitters to examine changes in individual movement patterns over time. Most sea ducks appeared to resume normal day-to-day movements within a week after capture; however, they nested later and at lower rates during the year after capture compared with later years. While behavioral effects of transmitter implantation seem to be relatively short-term, energetics and breeding decisions may be affected over longer timescales.","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43943722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combined effect of anthropogenic noise and artificial night lighting negatively affect Western Bluebird chick development","authors":"D. Ferraro, My-Lan T. Le, C. D. Francis","doi":"10.1093/condor/duaa037","DOIUrl":"https://doi.org/10.1093/condor/duaa037","url":null,"abstract":"ABSTRACT Sensory pollutants such as anthropogenic noise and night lighting now expose much of the world to evolutionarily novel sound and night lighting conditions. An emerging body of literature has reported a variety of deleterious effects caused by these stimuli, spanning behavioral, physiological, population, and community-level responses. However, the combined influence of noise and light has received almost no attention despite the co-occurrence of these stimuli in many landscapes. Here we evaluated the singular and combined effects of these stimuli on Western Bluebird (Sialia mexicana) reproductive success using a field-based manipulation. Nests exposed to noise and light together experienced less predation than control and light-exposed nests, and noise-exposed nests experienced less predation than control nests, yet overall nest success was only higher in noise-exposed nests compared to light-exposed nests. Although exposure to light decreased nestling body condition and evidence was mixed for the singular effects of noise or light on nestling size, those nestlings exposed to noise and light together were smaller across several metrics than nestlings in control nests. Our results support previous research on the singular effects of either stimuli, including potential benefits, such as reduced nest predation with noise exposure. However, our results also suggest that noise and light together can negatively affect some aspects of reproduction more strongly than either sensory pollutant alone. This finding is especially important given that these stimuli tend to covary and are projected to increase dramatically in the next several decades. LAY SUMMARY Noise and light pollution often occur together, but their combined influence on wildlife is poorly understood. We manipulated traffic noise and artificial night lighting exposure at Western Bluebird nests. Relative to control nests, those exposed to noise experienced lower nest predation and produced more fledglings whereas chicks in nests exposed to light took longer to fledge and had lower body condition. Nests exposed to noise and light together produced smaller nestlings than control nests and, for some body measurements, those exposed to either noise or light alone.","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa037","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41244167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Historic and contemporary use of catfish aquaculture by piscivorous birds in the Mississippi Delta","authors":"P. C. Burr, Jimmy L. Avery, Garrett M. Street, B. Strickland, B. Dorr","doi":"10.1093/condor/duaa036","DOIUrl":"https://doi.org/10.1093/condor/duaa036","url":null,"abstract":"ABSTRACT Piscivorous birds are the primary source of catfish (Ictalurus spp.) depredation at aquaculture facilities in northwestern Mississippi. Of particular concern is the Double-crested Cormorant (Phalacrocorax auritus), which can cost aquaculture producers millions of dollars annually through the depredation of cultured fish. Historical research conducted in the early 2000s estimated cormorant use of aquaculture ponds in the region, but aquaculture area has decreased by more than 70% since those estimates were made. With less aquaculture available, we predicted cormorant densities on aquaculture would be greater today than historically. Applying a similar methodology as in historical studies, we used aerial surveys to collect data on cormorants at night roosts and using catfish aquaculture ponds during 3 consecutive winter seasons, beginning in 2015. Although the mean annual number of cormorants at roosts in the Delta during our study was 64% less than historically, we found no significant change in densities on aquaculture, suggesting that aquaculture area is likely the factor influencing cormorant occurrence in northwestern Mississippi. During contemporary surveys we also measured the abundance of Great Blue Herons (Ardea herodias) and Great Egrets (A. alba) on the aquaculture clusters, and built predictive models of abundance relative to variables associated with forage at and surrounding the clusters. We found abundance of all 3 species was strongly related to the amount of aquaculture area both within and surrounding a cluster, although patterns varied by species. Cormorant abundance was also greater on clusters with proportionately more food fish (≥20 cm in length) than fingerlings (<20 cm) and was positively related to the proximity and size of night roosts. The relationships described here can be used by producers and wildlife managers to predict the abundance of these piscivorous birds at aquaculture facilities and to design efficient management plans to mitigate potential impacts of depredation and disease. LAY SUMMARY Mississippi contains ∼60% of all catfish production in the U.S., and bird depredation costs producers millions of dollars annually. We studied how Double-crested Cormorants, Great Blue Herons, and Great Egrets use commercial catfish aquaculture in Mississippi. However, catfish production in Mississippi has declined by over 70% since its peak in the early 2000s, raising questions regarding bird use, particularly by cormorants. Does less aquaculture mean more cormorants per pond? Has the aquaculture decline affected cormorant abundance in the region, and is catfish aquaculture a driver of local bird abundance? To address these questions, we compared surveys of cormorants from the early 2000s with contemporary surveys. We found fewer cormorants in Mississippi today than in the past but cormorant density on ponds has not changed, suggesting a link to the amount of catfish ponds. Local abundance of all fish-eating birds su","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa036","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43469983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An invasive insect, hemlock woolly adelgid, indirectly impacts Louisiana Waterthrush nest site selection and nest survival in the southern Appalachians","authors":"L. C. Bryant, Tiffany A. Beachy, T. Boves","doi":"10.1093/condor/duaa027","DOIUrl":"https://doi.org/10.1093/condor/duaa027","url":null,"abstract":"ABSTRACT Eastern hemlock (Tsuga canadensis) is declining throughout the eastern United States due to hemlock woolly adelgid (Adelges tsugae Annand), an invasive insect from Asia. In the southern Appalachians, hemlock is concentrated in moist ravines and its decline threatens riparian ecosystems. Previous research on this invasion has focused on adelgid control and how hemlock decline affects community composition or forest processes; few studies have evaluated the consequences for demography of obligate riparian species. The Louisiana Waterthrush (Parkesia motacilla) is an obligate riparian species that could be sensitive to hemlock condition in this region, but how individuals respond to decline is currently unknown. To address this knowledge gap, we leveraged recent adelgid treatment efforts in Great Smoky Mountains National Park to evaluate the relationship(s) between hemlock decline and waterthrush habitat selection (foraging and nest site) and vital rates (nest and adult survival). We found that hemlock decline was unrelated to foraging habitat selection and apparent adult survival, but was related to nest site selection through an interaction with percent ground cover of exposed live tree roots: birds selected for nest sites in areas with more exposed live roots but only when hemlock was in poor condition. Nest survival was lower in areas where deciduous species (vs. evergreen species) dominated the understory, suggesting that adelgid invasion could indirectly impact waterthrush fitness depending on how vegetative succession proceeds following hemlock decline. Our results suggest that the short-term consequences of adelgid invasion on this riparian avian species are minimal in this area, but these relationships are likely dynamic and dependent on local habitat features and the predator community response to hemlock decline. LAY SUMMARY Although eastern hemlock decline caused by the invasive hemlock woolly adelgid is altering riparian habitats in the southern Appalachians, Louisiana Waterthrush (Parkesia motacilla) was minimally impacted, at least in the short term. Understanding the impacts of hemlock decline is necessary for strategic conservation efforts and management guidance for waterthrush and other species that rely on riparian habitats experiencing adelgid invasion and hemlock mortality. We predicted that, as an obligate riparian species, waterthrush would be sensitive to hemlock condition with respect to their habitat selection (foraging and nest site) and vital rates (nest and adult survival). Contrary to our predictions, hemlock condition was unrelated to foraging habitat selection and apparent adult survival and was only indirectly related to nest site selection and nest survival. Our results suggest that the short-term consequences of hemlock decline on waterthrush are minimal, but these relationships are dynamic and likely dependent on local habitat features, forest succession following hemlock decline, and predator community ","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa027","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48802745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Supportive wind conditions influence offshore movements of Atlantic Coast Piping Plovers during fall migration","authors":"P. Loring, J. McLaren, Holly Goyert, P. Paton","doi":"10.1093/condor/duaa028","DOIUrl":"https://doi.org/10.1093/condor/duaa028","url":null,"abstract":"ABSTRACT In advance of large-scale development of offshore wind energy facilities throughout the U.S. Atlantic Outer Continental Shelf (OCS), information on the migratory ecology and routes of federally threatened Atlantic Coast Piping Plovers (Charadrius melodus melodus) is needed to conduct risk assessments pursuant to the Endangered Species Act. We tagged adult Piping Plovers (n = 150) with digitally coded VHF transmitters at 2 breeding areas within the southern New England region of the U.S. Atlantic coast from 2015 to 2017. We tracked their migratory departure flights using a regional automated telemetry network (n = 30 stations) extending across a portion of the U.S. Atlantic Bight region, a section of the U.S. Atlantic coast, and adjacent waters of the Atlantic Ocean extending from Cape Cod, Massachusetts, to Cape Hatteras, North Carolina. Most adults departed within a 10-day window from July 19 to July 29, migrated nocturnally, and over 75% of individuals departed within 3 hr of local sunset on evenings with supportive winds. Piping Plovers migrated offshore directly across the mid-Atlantic Bight, from breeding areas in southern New England to stopover sites spanning from New York to North Carolina, USA, over 800 km away. During offshore migratory flights, Piping Plovers flew at estimated mean speeds of 42 km hr–1 and altitudes of 288 m (range of model uncertainty: 36–1,031 m). This study provides new information on the timing, weather conditions, routes, and altitudes of Piping Plovers during fall migration. This information can be used in estimations of collision risk that could potentially result from the construction of offshore wind turbines under consideration across large areas of the U.S. Atlantic OCS. LAY SUMMARY The Atlantic coast population of the Piping Plover is listed as “Threatened” under the U.S. Endangered Species Act. Previously, little was known about exactly when, under what conditions, and along which routes these shorebirds undertake their migration from nesting areas along the Atlantic coast to wintering sites extending to eastern Caribbean islands. To help fill these information gaps, we attached miniature digitally coded VHF transmitters to 150 adult Piping Plovers at nesting areas in southern New England and constructed 35 radio antenna towers along the Atlantic coast to track their routes during fall migration. Most of the Piping Plovers in our study departed from southern New England in late July, at sunset, with tailwinds supporting offshore migratory flights across the mid-Atlantic Bight to stopover areas spanning from coastal New York to North Carolina. During offshore migratory flights, Piping Plovers flew at estimated mean speeds of 42 km hr–1 and at altitudes of 288 m. Our results provide the first empirical data on Piping Plover flight routes, altitudes, and weather conditions during fall migration. This information can be used to estimate collision risk from offshore wind turbines currently under consid","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42414902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Annual adult survival drives trends in Arctic-breeding shorebirds but knowledge gaps in other vital rates remain","authors":"E. Weiser, R. Lanctot, Stephen Brown, H. Gates, J. Bêty, M. Boldenow, R. W. Brook, Glen S. Brown, Willow B. English, S. Flemming, S. Franks, H. Gilchrist, Marie‐Andrée Giroux, Andrew Johnson, S. Kendall, L. Kennedy, Laura Koloski, Eunbi Kwon, J. Lamarre, D. Lank, Christopher J. Latty, N. Lecomte, J. Liebezeit, Rebecca L. McGuire, L. Mckinnon, E. Nol, D. Payer, J. Perz, Jennie Rausch, Martin D. Robards, S. Saalfeld, Nathan R. Senner, P. Smith, M. Soloviev, D. Solovyeva, D. Ward, Paul F Woodard, B. Sandercock","doi":"10.1093/condor/duaa026","DOIUrl":"https://doi.org/10.1093/condor/duaa026","url":null,"abstract":"ABSTRACT Conservation status and management priorities are often informed by population trends. Trend estimates can be derived from population surveys or models, but both methods are associated with sources of uncertainty. Many Arctic-breeding shorebirds are thought to be declining based on migration and/or overwintering population surveys, but data are lacking to estimate the trends of some shorebird species. In addition, for most species, little is known about the stage(s) at which population bottlenecks occur, such as breeding vs. nonbreeding periods. We used previously published and unpublished estimates of vital rates to develop the first large-scale population models for 6 species of Arctic-breeding shorebirds in North America, including separate estimates for 3 subspecies of Dunlin. We used the models to estimate population trends and identify life stages at which population growth may be limited. Our model for the arcticola subspecies of Dunlin agreed with previously published information that the subspecies is severely declining. Our results also linked the decline to the subspecies' low annual adult survival rate, thus potentially implicating factors during the nonbreeding period in the East Asian–Australasian Flyway. However, our trend estimates for all species showed high uncertainty, highlighting the need for more accurate and precise estimates of vital rates. Of the vital rates, annual adult survival had the strongest influence on population trend in all taxa. Improving the accuracy, precision, and spatial and temporal coverage of estimates of vital rates, especially annual adult survival, would improve demographic model-based estimates of population trends and help direct management to regions or seasons where birds are subject to higher mortality. LAY SUMMARY Documenting population trends is essential for evaluating the conservation status of wild species such as Arctic-breeding shorebirds. Trends can be estimated with population surveys or by predicting population growth based on survival rates and fecundity, but both methods are challenging, especially for species with large or remote geographic distributions. We used recent broad-scale estimates of survival and fecundity to develop population models for 6 species of Arctic-breeding shorebirds. The arcticola subspecies of Dunlin is likely in severe decline, but our trend estimates for all species showed high uncertainty. Uncertainty around the values of annual adult survival rates was a key driver of the uncertainty around the trend estimates. Our work highlights the need for better estimates of annual adult survival, seasonal survival, juvenile survival, and breeding propensity for these Arctic-breeding shorebirds.","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48526612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Urbanization is associated with increased breeding rate, but decreased breeding success, in an urban population of near-threatened African Crowned Eagles","authors":"Rebecca Muller, A. Amar, P. Sumasgutner, Shane C. McPherson, C. Downs","doi":"10.1093/condor/duaa024","DOIUrl":"https://doi.org/10.1093/condor/duaa024","url":null,"abstract":"ABSTRACT Urban areas can be attractive to certain species because of increased food abundance and nesting availability, which in turn may increase productivity or breeding rates. However, there are also potential costs associated with urban living such as higher nest failure, poorer body condition, or increased prevalence of disease. These costs may result in species trading off the number of young produced against the condition of their young. African Crowned Eagles (Stephanoaetus coronatus) are a rare example of large, powerful apex predators that breed in some urban areas in Africa. In this study, we explored the breeding performance of these eagles across an urbanization gradient in KwaZulu-Natal Province, South Africa, over 7 breeding seasons. We predicted that living in an urban environment would increase productivity through an increase in breeding rate (shifting from typically biennial breeding to annual breeding). We then explored if there were any hidden costs associated with such a change in breeding strategy by examining the body condition of chicks from pairs that had successfully bred in the previous year. We found that pairs in more urban areas were more likely to breed annually, resulting in higher breeding rates, but were also less likely to successfully fledge a chick (i.e. lower breeding success). These 2 contrasting responses counteracted each other and resulted in similar productivity across the urbanization gradient. For those eagles that bred in consecutive years, annual breeding did not appear to have a negative cost on chick condition. The switch to annual breeding is thought to be a response to improved or more constant food sources in urban areas, while higher failure rates might be because of increased nest disturbances from anthropogenic sources (e.g., vegetation clearing, development of industrial areas, human and car traffic). However, although urbanization negatively affected the breeding success of African Crowned Eagles, they are able to persist and thrive in this highly transformed environment, likely through an increased breeding rate. LAY SUMMARY One species that is hardly recognized as an urban adapter is the Crowned Eagle in the metropoles of Durban and Pietermaritzburg, South Africa. We explored the breeding performance of Crowned Eagles across different levels of urbanization, and specifically teased apart breeding rate (i.e. if an eagle breeds annually or every other year) and breeding success (i.e. if they fledge a young or not in a given year). We showed that Crowned Eagles change their breeding strategy in urban areas by increasing their breeding rate, but found nest failures occurred more often at more urbanized sites. These contrasting responses counteracted each other and resulted in similar productivity across the urbanization gradient and highlighted the value of long-term data.","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa024","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46126474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Habitat openness and edge avoidance predict Saltmarsh Sparrow abundance better than habitat area","authors":"H. Marshall, Erik J. Blomberg, Valerie K. Watson, M. Conway, J. Cohen, M. Correll, C. Elphick, T. Hodgman, Alison R. Kocek, A. Kovach, W. G. Shriver, Whitney A. Wiest, Brian J. Olsen","doi":"10.1093/condor/duaa019","DOIUrl":"https://doi.org/10.1093/condor/duaa019","url":null,"abstract":"ABSTRACT The Saltmarsh Sparrow (Ammospiza caudacuta) is a tidal marsh bird facing rapid population decline throughout its range, largely caused by degradation and loss of breeding habitat. Thus, there is a need to preserve tidal marshes in the northeastern United States, but to do so requires an understanding of the habitat features that support robust populations. Previous studies have shown Saltmarsh Sparrow abundance increases with marsh size, but in similar bird species, area sensitivity is more directly linked to edge avoidance. Whether additional landscape features affect the abundance of Saltmarsh Sparrows is unknown. We explored how the height of objects on the horizon, an index of habitat openness, affected the abundance of Saltmarsh Sparrows. Our primary goal was to determine whether the angle to the highest point on the horizon (“angle to maximum horizon”) predicted abundance better than marsh area or distance to the marsh edge. We used N-mixture models to evaluate the combination of spatial factors that best predicted Saltmarsh Sparrow abundance while also accounting for survey-level variables that could influence detection probability. We found that the interaction between distance to edge and angle to maximum horizon best predicted abundance. Taller objects on the horizon were negatively correlated with bird abundance, and this effect was strongest within 50 m of the marsh edge. When we considered the predictive powers of patch area, distance to edge, and angle to maximum horizon individually, angle to maximum horizon was the best single predictor. We found the highest abundance of Saltmarsh Sparrows at point locations where the angle to maximum horizon was 0.0°, and at angles greater than 12° the predicted abundance fell below 1 bird per survey point. We propose that managers should prioritize marsh openness and experimentally test the effect of marsh edge manipulations when making conservation decisions for this rapidly declining species.","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42458716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Birds suppress pests in corn but release them in soybean crops within a mixed prairie/agriculture system.","authors":"Megan B Garfinkel, Emily S Minor, Christopher J Whelan","doi":"10.1093/condor/duaa009","DOIUrl":"10.1093/condor/duaa009","url":null,"abstract":"<p><p>Birds provide ecosystem services (pest control) in many agroecosystems and have neutral or negative ecological effects (disservices) in others. Large-scale, conventional row crop agriculture is extremely widespread globally, yet few studies of bird effects take place in these agroecosystems. We studied indirect effects of insectivorous birds on corn and soybean crops in fields adjacent to a prairie in Illinois (USA). We hypothesized that prairie birds would forage for arthropods in adjacent crop fields and that the magnitude of services or disservices would decrease with distance from the prairie. We used bird-excluding cages over crops to examine the net effect of birds on corn and soybean grain yield. We also conducted DNA metabarcoding to identify arthropod prey in fecal samples from captured birds. Our exclosure experiments revealed that birds provided net services in corn and net disservices in soybeans. Distance from prairie was not a significant predictor of exclosure treatment effect in either crop. Many bird fecal samples contained DNA from both beneficial arthropods and known economically significant pests of corn, but few economically significant pests of soybeans. Song Sparrows (<i>Melospiza melodia</i>), one of our most captured species, most commonly consumed corn rootworms, an economically significant pest of corn crops. We estimated that birds in this system provided a service worth approximately US $275 ha^-1 in corn yield gain, and a disservice valued at approximately $348 ha^-1 in soybean yield loss. Our study is the first to demonstrate that birds can provide substantial and economically valuable services in field corn, and disservices in soybean crops. The contrasting findings in the 2 crop systems suggest a range of bird impacts within widespread agroecosystems and demonstrate the importance of quantifying net trophic effects.</p>","PeriodicalId":50624,"journal":{"name":"Condor","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2020-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7243448/pdf/duaa009.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37994622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}