Temporal and Seasonal Variation of Predator Visitation to Exclosed Piping Plover (Charadrius melodus) Nests at Jones Beach State Park, New York

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1 SUNY College of Environmental Science and Forestry Digital ESF Honors Theses Summer Temporal and Seasonal Variation of Predator Visitation to Exclosed Piping Plover (Charadrius melodus) Nests at Jones Beach State Park, New York Alicia Protus Follow this and additional works at: Part of the Ornithology Commons Recommended Citation Protus, Alicia, "Temporal and Seasonal Variation of Predator Visitation to Exclosed Piping Plover (Charadrius melodus) Nests at Jones Beach State Park, New York" (2016). Honors Theses. Paper 81. This Thesis is brought to you for free and open access by Digital ESF. It has been accepted for inclusion in Honors Theses by an authorized administrator of Digital ESF. For more information, please contact digitalcommons@esf.edu.

2 Temporal and Seasonal Variation of Predator Visitation to Exclosed Piping Plover (Charadrius melodus) Nests at Jones Beach State Park, New York. by Alicia Protus Candidate for Bachelor of Science Environmental Forest Biology With Honors August 2016 APPROVED Thesis Project Advisor: Jonathan B. Cohen, Ph.D. Second Reader: Shannon L. Farrell, Ph.D. Honors Director: William M. Shields, Ph.D. Date: 1

3 Abstract Significant resources have been spent attempting to manage predators of the threatened piping plover (Charadrius melodus). Various nest predator species are active throughout the day and night while monitoring staff that might deter predators are usually present only during select hours of the day. Monitoring efforts are also uniform throughout the nesting season, while predator activity may not be. The purpose of this study was to identify potential critical periods throughout the 24-hr cycle and the breeding season of the piping plover to allow for more targeted allocation of resources for monitoring nest predators. Camera traps were installed near exclosed piping plover nests (N= 16) at Jones Beach State Park, New York during egg incubation. Potential nest predators were identified from camera observations, and visit frequencies were summarized by time and seasonal period. Red fox (n=12) were most prevalent from 03:00-06:00, while raccoon (n=8) visited primarily between 00:00-03:00. Avian predators (n= 39) including gulls, crows, and American oystercatcher visited nests mainly from 06:00-18:00. Visit frequency of mammals and oystercatcher did not vary seasonally, however, crows (n=13) only visited between 14 June and 5 July. Visitation amongst the different predator species had limited temporal overlap, with peak visitation times coinciding only for diurnal species. The mid-evening hours (21:00-23:59) had the lowest number of recorded predator visits. Major predator species often vary between sites, nonetheless, management activities during the breeding season may be optimized by incorporating the activity windows of their respective predator suite in their piping plover monitoring schedules.

4 ii Contents Table of Figures...ii Acknowledgements... iii Thesis... 1 Introduction... 1 Study Area... 3 Methods... 4 Results... 6 Discussion... 8 Conclusion Literature Cited Table of Figures Fig. 1. Study area at Jones Beach State Park in Wantagh, New York.. 4 Fig. 2. Piping plover adult incubating its nest, and a young chick standing just outside the predator exclosure device at Jones Beach State Park, NY.. 6 Fig. 3. Predator visits to exclosed piping plover nests at Jones Beach State Park, NY, classified by species and time of day... 7 Fig. 4. Predator visits to exclosed piping plover nests at Jones Beach State Park, NY, classified by species and date. 7

5 iii Acknowledgements I would like to thank the Honor s program at the SUNY College of Environmental Science and Forestry for their generous funding that made this project possible. I am grateful for the insight and valuable advice provided by my honors mentor Dr. Jonathan Cohen, and the encouragement from friend and mentor William Shields, director of the Honors program. Thank you to Dr. Shannon Farrell who provided valuable comments as my second reader. I am indebted to the staff at the Jones Beach Nature Center, particularly Madelyn Forte, who provided field assistance and valuable advice throughout the data collection process. This project also couldn t have been completed without the help of Thadeus Sternberg, who assisted in processing the many hours of nest video footage for sightings of nest predators. Finally, I would like to thank Ethan Miller for never complaining when my projects cut into our vacation time, and for nodding every time I showed you a cute picture of a piping plover.

6 1 Thesis Introduction The piping plover (Charadrius melodus) is a small, ground-nesting shorebird found along the east coast of the United States. The Atlantic coast population of the piping plover is listed as a threatened species under the Endangered Species Act of 1973 due to threats such as predation, habitat loss and human disturbance (USFWS 1985). Mammalian and avian predation have been determined to be significant factors limiting reproductive success and have become a focus of management practices (Plissner and Haig 2000, Cohen et al. 2009). The nature and severity of predation is highly site specific, but species such as red fox (Vulpes vulpes), raccoon (Procyon lotor), feral cats (Felis catus), gulls (Laridae spp.), and corvids (Corvus spp.) are common predators of piping plovers on the north Atlantic coast (USFWS 1996). The introduction of predator exclosure cages has increased hatching success in piping plovers (Melvin et al. 1992), however, the exclosure devices may have some drawbacks such as increased predator awareness of the nest site, which can contribute a new source of mortality. Red fox have been shown to linger near exclosed piping plover nests more than non-exclosed nests (Beaulieu et al. 2014). In addition, avian predators have been documented to harass or predate adult piping plovers with exclosed nests while ignoring control nests (Murphy et al. 2003). In one case with similarly exclosed Western sandpiper nests, avian predators raided nest contents within minutes of the exclosures being removed (Niehaus et al. 2004). One approach used in tandem with predator exclosures to improve reproductive success is daily monitoring of the birds, nests, and predators in the area. Though animals like red fox can become habituated to humans, they typically display avoidance behavior

7 2 and react negatively to being approached, especially when done in a threatening manner (Díaz Ruiz et al. 2016). Human presence can be used as a deterrent to chase or startle predators away from piping plover adults, chicks, and nests, helping to prevent predation attempts when possible. Lindsey (1992) demonstrated that intensive monitoring of Puerto Rican parrot (Amazona vittata) nests and intervention by monitors helped reduce predation and nest failure, increasing nest success by 28%. Presently, at beaches with substantial piping plover populations, monitoring stewards are typically assigned to monitor the birds and their habitat from the late morning until early evening. Conversely, piping plover nest predators are active during both the day and night, leaving nests unattended by monitoring staff for approximately half of the 24-hr cycle. Evidence from observations of the 2014 piping plover breeding season at Robert Moses State Park, NY suggested that the piping plover monitoring regime was not optimal, as many instances of chick loss and predator-induced abandonment of nests likely occurred outside of typical steward monitoring hours. The cause of chick loss in most cases was unknown, though predation was suspected based on the high activity of various predator species at the site. Potentially preventable chick mortality and predator-induced abandonment of nests likely occurred several times throughout the season, presumably in the late evening or early morning hours prior to the arrival of monitoring staff. However, given limited conservation funds and resources, round the clock monitoring of piping plovers is considered an impractical management option for the vast majority of conservation agencies. Therefore, targeting key points during the piping plover breeding season to make the most effective use of monitoring time is an important objective.

8 3 The purpose of this study was to assess whether there are critical windows of time in which predators are more likely to visit exclosed piping plover nests in order to optimize monitoring activities. I hypothesized that the likelihood of mammalian and avian predator visits to piping plover nests varies temporally and seasonally. Potential variation in the timing of predator visits would allow managers to target windows of high predation risk for monitoring to improve reproductive success of piping plovers. Study Area The location of this study was the ocean beachfront of Jones Beach State Park, Wantagh, New York, west of the Field 2 beach access (40 35'31.69"N, 73 31'14.85"W, Fig. 1). The area west of the Field 2 beach access consists of roughly 4.8 km of ocean beachfront and encompasses six of the nine major piping plover nesting sections within the park. Jones Beach State Park as a whole consists of 10.5 km of oceanfront beach, which hosted an average total of 35 piping plover pairs over the course of the breeding seasons (per. comm. McIntyre, NYS OPRHP 2015). Jones Beach State Park is visited by approximately six million people per year, with the bulk of recreation activities occurring east of the Field 2 beach access, but also at West End 1 within the study area of this project (NYS OPRHP, 2016). Monitoring at this site was conducted from 3 June until the end of the piping plover breeding season on 16 July 2015.

9 4 1 km Figure 1. Study area at Jones Beach State Park in Wantagh, New York. The red vertical line on beach indicates the Field 2 beach access; west of the red line is considered the study area. Regional context for the study area is shown in the upper left hand corner. Methods I installed seven camera traps (model C, Bushnell, Overland Park, Kansas) approximately 4.5 m south piping plover nests (N= 16) at Jones Beach State Park after they were exclosed. I mounted the cameras on 1.5 m iron sign posts and enclosed the equipment in locked security boxes to discourage theft or damage. The cameras took timed photographs every five minutes, and also when triggered by motion activity in the frame. Each camera was left recording on the nest until the chicks hatched and the exclosed nest site was left by the brood. I rotated the cameras onto new nests as hatching occurred, prioritizing nests by selecting ones with the largest estimated length of incubation time remaining.

10 5 After collection, I identified photographed predators and documented the time and date of each predator visit. Along with red fox, raccoon, gulls, and crows, American oystercatcher (Haematopus palliates) visits were also recorded as predator visits in this study. The presence of American oystercatchers elicits the same defensive action from the adult plovers as predators, and the species have been noted to attack adult piping plovers, as well as chicks and eggs, though the behavior may simply be a territorial response (Wilke and Denmon 2014). I recorded all photographed predators as predator visits, regardless of whether the animal appeared to be actively investigating the nest or exclosure, due to the predator s close proximity to the nest. I reviewed the photographs as stop motion video with Scouting Assistant- Field Scan Time Lapse software (Chasingame Outdoors 2011) to document the date and time of piping plover chick hatching for each nest, as well when the adults and brood left the exclosed nest site for the final time (Fig. 2). Because the cameras were not extremely sensitive, I additionally searched the photos for any predators photographed without the use of the motion trigger. For the temporal analysis of predator visits, I divided the 24-hr cycle into five time periods, with 06:00-18:00 comprising one large daytime period and the rest of the hours being split into four three-hour long time blocks. For seasonal analysis, I also divided the monitored length of the breeding season into four periods of 11 days. I summarized the predator visits by species, time, seasonal period, and proximity of the visit to hatching date. R software (R Core Team 2016) was used to calculate chi-squared values to test for statistical significance for time and seasonal periods.

11 6 Figure 2. Piping plover adult incubating its nest, and a young chick standing just outside the predator exclosure device at Jones Beach State Park, NY. Results Sixteen nests were monitored with camera traps over the course of the breeding season. Over 40 hours worth of stop-motion video playback was created from the collected camera stills. Because of the rotational deployment of the camera onto incubating nests, the total number of days monitored per nest varied from two days to several weeks. A total of 60 predator visit events were recorded at exclosed piping plover nests throughout the breeding season, from six different species. The patterns of predator visitation predictably correlated roughly with the activity period (i.e., diurnal, nocturnal, crepuscular) of each predator species (Fig. 3). Red fox (n= 12) were significantly more likely to visit an exclosed piping plover nest between 03:00 and 05:59, while raccoon (n=8) visited between 00:00 and 02:59. Avian predators (n=39) including gulls, crows, and American oystercatcher visited nests from 06:00 to 17:59 significantly more than any

12 Number of Predator Visits Number of Predator Visits 7 other time period in the 24-hr cycle. One occurrence of a feral cat at an exclosed piping plover nest was also recorded at 23:00. The presence of mammalian and avian predator species at piping plover nests did not vary significantly across the breeding season, except for crows (n=13), which only visited the nests between 14 June - 5 July (Fig. 4) Temporal Variation in Piping Plover Nest Predator Visits Fox* Raccoon* Oystercatcher* Crow* Gull Cat 00:00-02:59 03:00-05:59 06:00-17:59 18:00-20:59 21:00-23:59 Time Period (hr) Figure 3. Predator visits to exclosed piping plover nests at Jones Beach State Park, NY, classified by species and time of day. *= P < =insufficient data for analysis Seasonal Variation in Piping Plover Nest Predator Visits Fox Raccoon Oystercatcher Crow* Gull Cat June June 25 June- 5 July 6-16 July Seasonal Period Figure 4. Predator visits to exclosed piping plover nests at Jones Beach State Park, NY, classified by species and date. *= P < =insufficient data for analysis. No symbol= P > 0.05.

13 8 Discussion Visitation amongst the different predator species had limited temporal overlap, with peak visitation times coinciding only for diurnal species. However, visitation by fox and raccoon overlapped with significant activity by both species occurring between the hours of 00:00 to 06:00. At many sites, red fox and raccoon are abundant and can pose a significant threat to piping plovers. This window of time may be of interest to target for monitoring at sites with an abundance of these predators, as sites are typically not monitored during the late evening to early morning hours. Considering that predation and predator presence at nests are often a limiting factor for piping plovers in the Long Island region (Cohen et al. 2009, Doherty and Heath 2011), providing additional monitoring during the late evening and pre-dawn hours has the potential to improve the reproductive success of the piping plovers. Patterns in the seasonal frequency of predators at piping plover nests were not apparent except for the corvid species. The camera observation of crows at nests were only recorded between 14 June and 5 July. Only three piping plover nests were visited by crows, with 12 of the 13 recorded crow visits occurring at two nests located approximately 0.25 km of each other. These plover nests were also located under 0.5 km from the Field 2 concessions area. A study by Chamberlain-Auger et al. (1990) observed that the young of American crows hatch and remain in the nest for approximately 30 days, mainly during the months of May and June, with a range from April to July. The observed dates of crow visitation to piping plover nests are likely the result of foraging to support nestlings. The localized pattern of crow visitation may due to the piping plover nests being located within or near the home range of the crow pair, though no crow nest

14 9 was observed during the site visits. Crows have been demonstrated to have smaller home ranges, higher reproduction, and higher survival rates near human recreation areas and settlements (Marzluff and Neatherlin 2006). In this study, corvids accounted for over 21% of total predator visits. In a study by Marzluff and Neatherlin (2006), corvids accounted for 32.5% of all predation events (n = 837) on artificial marbled murrelet (Brachyramphus marmoratus) nests, demonstrating their potential to cause significant damage to ground nesting species. Harassment and predation by crows may not be a uniform threat across the piping plover nesting areas at Jones Beach State Park, however, managers should be aware that the establishment of a crow nest can pose a significant, though localized, threat. One topic for future study should include whether there is a relationship between the proximity of the piping plover nest to human refuse disposal areas and predator visitation to nests. Substantial evidence shows that human activities are affecting the abundance and activity of predators in beach ecosystems, exacerbating the risk of predation for piping plovers (USFWS 1996). No data was recorded in this study regarding exact locations of nests in regards to distance to nearest human refuse collection/ area of human activity, however, anecdotal observations indicated that two nests located approximately 500 meters directly south of a concessions area accounted for seven of the eight recorded raccoon visits. The remaining raccoon visit occurred at a nest situated between two boardwalk/concession areas that were located approximately 1 km apart. The abundance and distribution of food resources play a large role in the movements and spatial distribution of solitary carnivores, like raccoons (Prange et al. 2004). This pattern has also been observed with corvids, as discussed previously. Piping

15 10 plover nests located near hot spots of human activity on the beach landscape may not only be at risk from direct human-related disturbance, but also predation by the suite of predators attracted to the area. Discerning the level of threat experienced by piping plover nests near human recreation areas will aid in developing more specific management protocols for these scenarios. Nests at higher risk for human and predator disturbance could be prioritized by staff for monitoring and other management action such as erecting electric or snow fencing as additional predator deterrents. Another potential topic for future study is whether the frequency of predator visits increases several days prior and following the hatching of the chicks at a nest. I hypothesize that predators can utilize the auditory cues that likely accompany the hatching of the chicks, such as egg pipping (Gottlieb and Vandenbergh 2005) and more frequent vocalizations from the adults when communicating with their offspring (Johnson et al. 2008), to locate and subsequently attempt to predate nests. Anecdotal evidence from this study indicated that four of the 11 predator fox visit nights occurring within 3 days of hatching, possibly indicating support for this hypothesis. However, because of the methods employed in this study, sampling was biased toward the latter 14 days of the incubation period for the majority of nests. This, combined with the small sample size of predator visits, inhibits drawing any conclusions regarding the frequency of fox visits in relation to the nest hatching date from this study. Red fox have been documented to use the predator exclosures as visual cues (Beaulieu et al. 2014), so combined with potential auditory cues with the arrival of chicks, this may be a vulnerable window of time for nesting piping plovers. With most chick mortality occurring when the chicks are young (<15 days), increasing monitoring efforts immediately prior and following hatching has

16 11 the potential to improve piping plover reproductive success with minimal additional monitoring efforts (MacIvor 1990). The monitoring regime at piping plover nesting sites can be optimized by including the activity patterns of their threatening predators in their monitoring schedule, but these factors must be balanced with other concerns such as policing human activity on beaches during the daytime. With the implementation of symbolic fencing, however, human disturbance is less of a threat to piping plover reproductive success. According to a study by Doherty and Heath (2011), predator activity was the cause of low reproductive success at their Long Island sites, not human disturbance. Expansion of the monitoring hours for piping plovers has both costs and benefits, and appropriate actions will vary for each site. Conclusion Though piping plover numbers are on the rise after becoming a listed species, predation and predator-induced nest abandonment are still major factors limiting their reproductive success (Cohen et al. 2009, Doherty and Heath 2011). This study demonstrates that peak visitation hours for avian predators at exclosed piping plover nests were during the daytime (06:00-17:59) and these times coincides with typical piping plover monitoring hours (08:00-17:00). However, the same is not true for the peak visitation of red fox (03:00-05:59) and raccoon (00:00-02:59) in the late evening and early morning hours. Major predator species often vary between sites, nonetheless, management activities during the breeding season may be optimized by incorporating the activity windows of their respective predator suite in their piping plover monitoring schedules.

17 12 Literature Cited Beaulieu, G., D. Austin, and M. Leonard Do nest exclosures affect the behaviour of piping plovers (Charadrius melodus melodus) and their predators? Canadian Journal of Zoology 92: Cohen, J.B., L.M. Houghton, and J.D. Fraser Nesting density and reproductive success of piping plovers in response to storm- and human created habitat changes. Wildlife Monographs 173: Díaz Ruiz, F., J. Caro, M. Delibes Mateos, B. Arroyo and P. Ferreras Drivers of red fox (Vulpes vulpes) daily activity: prey availability, human disturbance or habitat structure? Journal of Zoology 298: Doherty, P. J., and J.A. Heath Factors affecting piping plover hatching success on Long Island, New York. The Journal of Wildlife Management 75: Gottlieb, G., and J.G. Vandenbergh Ontogeny of vocalization in duck and chick embryos. Journal of Experimental Zoology 168: Johnson, M., S. Aref and J.R. Walters Parent offspring communication in the western sandpiper. Behavioral Ecology 19: Lauro, B., and J. Tanacredi An examination of predatory pressures on piping plovers nesting at Breezy Point, New York. Waterbirds 25: Lindsey, G. D Nest guarding from observation blinds: strategy for improving Puerto Rican parrot nest success. Journal of Field Ornithology 63: MacIvor, L.H Population dynamics, breeding ecology, and management of piping plovers on outer Cape Cod, Massachusetts. M.S. Thesis, Univ. Massachusetts, Amherst. 100pp. Marzluff, J. M., and E. Neatherlin Corvid response to human settlements and campgrounds: causes, consequences, and challenges for conservation. Biological conservation 130: Melvin, S.M., L.H. MacIvor and C.R. Griffin Predator exclosures: a technique to reduce predation at piping plover nests. Wildlife Society Bulletin 20: Murphy, R.K., I.M.G. Michaud, D.R.C. Prescott, J.S. Ivan, B.J. Anderson and M.L. French-Pombier Predation on adult piping plovers at predator exclosure cages. Waterbirds 26:

18 13 New York State Park Parks, Recreation and Historic Preservation [NYS OPRHP] Jones Beach State. Retrieved July 02, 2016, from Niehaus, A.C., D.R. Ruthrauff and B.J. McCaffery Response of predators to Western sandpiper nest exclosures. Waterbirds 27: Plissner, J. H., and S.M. Haig Viability of piping plover Charadrius melodus metapopulations. Biological Conservation 92: Prange, S., S.D. Gehrt and E. P. Wiggers Influences of anthropogenic resources on raccoon (Procyon lotor) movements and spatial distribution. Journal of Mammalogy 85: R Core Team R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN , URL U.S. Fish and Wildlife Service [USFWS] Determination of endangered and threatened status for the piping plover. Federal Register 50: U.S. Fish and Wildlife Service [USFWS] Piping plover (Charadrius melodus), Atlantic coast population- revised recovery plan. Hadley, Massachusetts. 258 pp. Wilke, A., and P. Denmon Behavior American Oystercatcher Working Group. Retrieved June 20, 2016, from behavior/