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2016 Sussman Internship Report Michelle Stantial Factors Limiting Abundance and Productivity of Piping Plovers (Charadrius melodus) in Southern New Jersey Michelle L. Stantial SUNY College of Environmental Science and Forestry, Dept. Environmental and Forest Biology, Syracuse, NY Summary During the 2016 breeding season a total of 591 hours were spent in the field from April 15 - August 15 at seven study sites in New Jersey: Barnegat Lighthouse State Park, Edwin B. Forsythe NWR (Holgate Unit), North Brigantine Natural Area, Malibu Wildlife Management Area, Avalon-Dunes, Stone Harbor Point, North Wildwood, and Cape May Point State Park (Fig. 1). Activities included trapping, banding, and radio-tagging adult and hatchling piping plovers, weekly resighting surveys, weekly chick captures, and bi-monthly predator occupancy surveys. Our goals of this study are to provide recommendations for predator management and restoration to land managers within the state of New Jersey that will simultaneously reduce predation pressures and create suitable habitat to begin recovery in the state. 1 2016 Sussman Internship Report Michelle Stantial Introduction Successful recovery of endangered species requires an understanding of factors that limit population size and growth rate. Population dynamics typically vary depending on the reproductive success of individuals, which can be influenced by a number of factors including environmental impacts, habitat loss and predation. High reproductive success can lead to increases in abundance and dispersal rates, influencing regional population growth. The Atlantic coast population of piping plovers (Charadrius melodus) was listed as threatened under the U.S. Endangered Species Act (ESA) in 1986. Since listing, the population has increased from 790 pairs in 1986 to more than 1,898 pairs in 2012 (USFWS 2013), a 140 percent increase. Although conservation of this species has seen great recovery success through protection and management, recovery units within the Atlantic coast population have seen fluctuations in growth in recent years. From 2007 to 2010, the total Atlantic Coast population experienced a 6% decline; the Eastern Canada and New York-New Jersey recovery unit populations decreased 15% and the Southern recovery unit population experienced an 8% decrease, however, the New England recovery unit grew 7% during the same time period (USFWS 2011). Major causes of decline and continued threats to the recovery of the Atlantic coast piping plover population include degradation of breeding and foraging habitat, anthropogenic disturbances, and increased rates of predation compared to pre-settlement times (Wilcox 1959, Burger 1994, USFWS 1996, Maslo et al. 2012). Population monitoring is an integral part of recovery efforts for Atlantic Coast Piping Plovers (USFWS 1996, Hecht and Melvin 2009). Monitoring allows wildlife managers to identify limiting factors of survival and productivity, assess effects of management actions and regulatory protection, and track progress toward recovery. A coast-wide effort to summarize data on abundance, distribution, and reproductive success of piping plovers has continued since the species’ ESA listing. Recovery actions include procedures to reduce the amount of habitat loss due to human development and management techniques to protect adults, eggs, and chicks from predators and disturbance (Hecht and Melvin 2009). Management techniques include extensive monitoring of breeding pairs from the time of arrival on the nesting grounds until the time of departure, symbolic fencing to provide buffers around nesting areas preventing human disturbance, predator management including the use of exclosures to protect nests (Melvin et al. 1992), and off-road vehicle restrictions to allow broods to forage without the threat of being crushed by a vehicle. Removal of a species from protections of the ESA requires both increases in abundance, distribution and reproductive success as well as improvements in factors that led to listing of the species (Hecht and Melvin 2009). Despite intensive management that aligns with recovery plan guidelines, the population of piping plovers nesting in New Jersey has seen no increase in abundance since the species listing. The goal of this study is to understand the roles of predators and foraging habitat in piping plover population dynamics in New Jersey piping plovers. Our results will lead to more comprehensive recommendations for predator management and restoration in regards to chick foraging to land managers within the state of New Jersey that will simultaneously reduce predation pressures and create suitable habitat to begin recovery in the state. Methods Monitoring, Nest, and Chick Survival In collaboration with NJESP, CWFNJ and the Wetlands Institute, a total of 53 nests from 40 pairs of piping plovers were monitored at a total of seven study sites from Barnegat Light State Park to Stone Harbor Point. Field crews attempted to assess nest fate (i.e., active, hatched, depredated, overwashed, abandoned, weather loss, unknown cause of loss, or unknown fate [nest not present, unsure of hatch or nest loss]) every 1-3 days. For nests that hatched, we attempted to determine brood fate within established territories or proximity of banded parents, every 1-3 days until all chicks had fledged or were assumed dead based on the absence of the chicks and parents. We used logistic exposure models (Shaffer 2004) to compare daily nest survival at each of our study sites using data from 2012-2016. We included random slopes and coefficients by site for the linear predictor in our nest survival models because baseline probabilities of nest predation may depend on site-specific factors such as predator communities. We also included an effect of nest exclosure. We used Young survival models (Lukacs et al. 2004) to compare daily chick survival between broods at each of our study sites using data from 2012-2016. We included random slopes and coefficients by site for our Young survival model 2 2016 Sussman Internship Report Michelle Stantial because baseline probabilities of chick survival may depend on site-specific factors such. We also included a random effect of site on detection probability because visit frequency varied among sites. We used continuous feed cameras at a subset of nests to verify causes of nest loss and document predator visits when the nest was not lost. We recorded more than 5000 hours of video footage from the 2015 and 2016 field seasons which will continue to be analyzed during the winter of 2016-2017. Adult Nest Trapping and Chick Captures We spent a total of 55.4 hours trapping piping plover adults and 100.0 hours capturing piping plover chicks during the 2016 field season. A total of 33 piping plovers adults were trapped and newly banded in New Jersey during the 2016 field season, and a total of 25 piping plover adults were equipped with radio-tags. A total of 100 piping plover chicks were banded and 21 were equipped with radio-transmitters (Table 1). Chicks were recaptured and weighed every 5-7 days. No injuries occurred as a result of handling. No injuries occurred as a result of transmitter attachment, all birds receiving radio-tags appeared to incubate nests, tend broods, and otherwise behave normally. Resighting Surveys We spent a total of 325.2 hours resighting individually marked piping plover adults and chicks during the 2016 field season. Resighting surveys were conducted once a week and all areas of potential nesting and foraging habitat at each study site were searched for banded adults and chicks. Habitat Use We spent a total of 42.0 hours conducting behavioral observations of banded adults and chicks to assess habitat use across a variety of different nesting and foraging habitat configurations and varying levels of recreational beach use. Behavioral observations were 10 min periods where every 10 seconds the behavior of the adult or chick was recorded as either foraging, resting, courting, territorial, incubating, brood tending or disturbed. Additionally, each time an adult or chick actively pecked at the substrate to capture a prey item, this action was recorded. We used Multi-Response Permutation Procedure (MRPP) (Talbert and Cade 2013) to test for differences in activity budgets and time spent in various habitat types for chicks and adults amongst all of our study sites. Predator Occupancy Surveys We spent a total of 144.5 hours conducting predator surveys at piping plover breeding sites during the 2016 field season. Predator surveys were conducted once every two weeks (twice per month). We conducted bi-weekly mammalian predator track surveys and avian point count surveys at randomly located plots at each of our study sites. During each survey, we counted the number of track trails present in each plot by predator species and identify all avian species present within 100 m of the center of the plot. We recorded plot-specific covariates that may affect occupancy such as the distance to the dune, distance to the forest, and distance to human development, survey-specific covariates that may affect occupancy such as the distance to human recreation, the number of humans present, the distance to the nearest American oystercatcher nest, and the distance to the nearest least tern nest, and survey specific covariates that may affect detection rate, such as the saturation of the substrate, weather conditions, and tracking conditions. We used dynamic occupancy models (MacKenzie et al. 2005, Kéry and Schaub 2012) to estimate the probability of habitat use by red foxes and track how of predator habitat use changes throughout the course of the nesting season. Radio Telemetry Two automated telemetry units were placed in the field to monitor the daily activity patterns of radio-tagged piping plovers. One tower was placed at the Holgate unit of EB. Forsythe NWR and was in operation for a total of 75 days during the breeding season. A second tower was located at North Brigantine Natural Area and was in operation for a total of 69 days. Results Monitoring, Nest, and Chick Survival For the 2016 season, 62 piping plover chicks were fledged from the monitored study sites, representing a fledge rate of 1.62 chicks/pair, exceeding the minimum requirement of 1.21 chicks/pair as required to maintain a stable population. 3 2016 Sussman Internship Report Michelle Stantial This region has observed an increase in reproductive success since 2012 when only 0.33 chicks/pair fledged from the same seven study sites. Nest loss due to predators such as red foxes, fish crows, and large gulls has been cited as the primary cause of poor hatch success, yet the causes of chick loss are largely unknown. During 2016, the primary causes of nest loss in the study region was due to flooding (n=5). Other causes of nest loss included unknown predation (n=2), Virginia opossum (n=2), raccoon (n=2), abandonment (n=2), fox (n=1), skunk (n=1), American oystercatcher (n=1), buried by sand (n=1), and hatching failure (n=1). Daily nest survival was similar across all study sites but lowest at Stone Harbor point for both exclosed and unexclosed nests, and exclosures had a significant effect on daily nest survival (Fig. 2). Chick survival was found to vary among study sites (Fig. 3). We documented incidents of fish crow, herring gull, laughing gull, red fox, and mink removing eggs from nests in 2015 video footage and skunks removing eggs in 2016 video footage. Habitat Use We found no differences in activity budgets for adults and chicks at all of our study sites. However, we did find differences in the amount of time that adults and chicks spent in various habitat types at each of our study sites (Figs. 4 and 5). Predator Occupancy Surveys Distance to dune was the only significant covariate. As the distance to the dune increased, the probability of habitat use by red foxes decreased (Fig 6). Ongoing analysis includes occupancy of all other predator species to each of our study sites, chick growth rates, weekly survival of adults and chicks, review of automated telemetry data, and review of nest camera video footage. Acknowledgments This project was funded by the Edna Bailey Sussman Foundation, U.S. Fish and Wildlife Service, National Fish and Wildlife Foundation, and the New Jersey Division of Wildlife. C. Davis, and T. Pover provided logistical support. R. Linhart, A. Bonk, B. Giblin, A. Damminger, K. Dudgeon, D. Tattoni, J. Freeman, and Z. Bailey collected and entered the data. Literature Cited Burger, J. (1994). The effect of human disturbance on foraging behavior and habitat use in piping plover (Charadrius melodus). Estuaries 17:695–701. Hecht, A., and S. M. Melvin (2009). Expenditures and Effort Associated With Recovery of Breeding Atlantic Coast Piping Plovers. The Journal of Wildlife Management 73:1099–1107. Kéry, M., and M. Schaub (2012). Bayesian population analysis using WinBUGS: a hierarchical perspective. In. 1st ed. Academic Press, Boston. Lukacs, P. M., V. J. Dreitz, F. L. Knopf, and K. P. Burnham (2004). Estimating survival probabilities of unmarked dependent young when detection is imperfect. The Condor 106:926–931. MacKenzie, D., J. Nichols, A. Royle, K. Pollock, L. Bailey, and J. Hines (2005). Occupancy Estimation and Modeling: Inferring Patterns and Dynmaics of Species Occurence. In. 1st edition. Academic Press. Maslo, B., J. Burger, and S. N. Handel (2012). Modeling Foraging Behavior of Piping Plovers to Evaluate Habitat Restoration Success. The Journal of Wildlife Management 76:181–188. Melvin, S. M., L. H. MacIvor, and C. R. Griffin (1992). Predator Exclosures: A Technique to Reduce Predation at Piping Plover Nests. Wildlife Society Bulletin (1973-2006) 20:143–148. Shaffer, T. L. (2004). A unified approach to analyzing nest success. The Auk 121:526–540. 4 2016 Sussman Internship Report Michelle Stantial Talbert, M. K., and B. S. Cade (2013). User Manual for Blossom Statistical Package for R. [Online.] Available at http://pubs.usgs.gov/of/2005/1353/. USFWS (1996). Piping Plover (Charadrius melodus) Atlantic Coast Population Revised Recovery Plan. USFWS (2011). Abundance and productivity estimates – 2010 update: Atlantic Coast piping plover population. USFWS (2013). Preliminary 2012 Atlantic Coast Piping Plover Abundance and Productivity Estimates. Wilcox, L. R. (1959). A Twenty Year Banding Study of the Piping Plover. The Auk 76:129–152. 5 2016 Sussman Internship Report Michelle Stantial Table 1. Sample sizes of banded and radio-tagged piping plovers in NJ, 2016. All radio-tagged birds were also banded, and are therefore included in both categories Adults Chicks Newly Previously Total Site Pairs Banded Banded Banded Avalon-Dunes (AVDU) 1 1 1 2 Barnegat Lighthouse State Park (BALI) 3 3 3 6 Cape May Point State Park (CMPSP) 0 0 0 0 E. B. Forsythe NWR – Holgate (HOLG) 25 24 25 49 a Island Beach State Park (IBSP) 1 0 0 0 Malibu Wildlife Management Area (MWMA) 0 0 0 0 North Brigantine Natural Area (NBNA) 5 0 10 10 North Wildwood (NOWI) 0 0 0 0 Stone Harbor Point (SHPT) 5 5 5 10 Total 40 33 44 77 a Island Beach State Park was not a study site, but two chicks were banded in 2016 for monitoring purposes. Radio Tagged 1 2 0 17 0 0 3 0 2 25 Newly Banded 3 8 0 62 2 0 16 0 9 100 Radio Tagged 1 3 0 12 0 0 3 0 2 21 6 2016 Sussman Internship Report Michelle Stantial Figure 1. Map of 2016 study sites in southern New Jersey. 7 2016 Sussman Internship Report Michelle Stantial Figure 3. Daily survival probability of chicks at each study site, 2012-2016. 8 2016 Sussman Internship Report Michelle Stantial Figure 2. Daily survival probability of unexclosed and exclosed nests at each study site, 2012-2016. 9 2016 Sussman Internship Report Michelle Stantial Figure 4. Amount of time adults spent within in each habitat type at each study site, 2016(MRPP, P < 0.01). 10 2016 Sussman Internship Report Michelle Stantial Figure 5. Amount of time chicks spent within each habitat type at each study site, 2016 (MRPP, P < 0.01). 11 2016 Sussman Internship Report Michelle Stantial Figure 6. Relationship between probability of fox habitat use and the distance to the nearest dune to the predator track survey plot. 12