Headstarting: An Experimental Study to Improve Nest Success of American Oystercatchers Samantha Collins 1,2, Patrick Jodice 1,2, Felicia Sanders 3, and Patrick Gerard4 Today we have heard about the status and nesting success of oystercatchers in NC, NJ, FL and TX. I am going to be presenting information about the nesting success of oystercatchers in South Carolina. 1 School of Agricultural, Forest and Environmental Sciences, Clemson University 2 US Geological Survey South Carolina Cooperative Fish and Wildlife Research Unit 3 South Carolina Department of Natural Resources 4 Department of Mathematical Sciences, Clemson University

POPULATION ESTIMATES Cape Romain Region (CRR) supports a majority of South Carolina’s breeding pairs and non breeding flocks Surveys and research have been conducted on this species in the CRR for the past 10 years breeding – ~400 breeding pairs/ ~380 non-breeding individuals (Sanders et al. 2008) wintering – 3,500 individuals (Sanders et al. 2004) South Carolina has the second highest number of breeding pairs along the Atlantic Coast and over half of these breeding pairs nest within the Cape Romain Region. Cape Romain Region is located north of Charleston and includes the Cape Romain National Wildlife Refuge and areas adjacent to it.

CAPE ROMAIN NWR 35 km segment of the southeast Atlantic coast Expanse of barrier islands, salt marshes, intricate coastal waterways, long sandy beaches, fresh and brackish water impoundments, and maritime forest Objectives = to preserve in public ownership habitat for waterfowl, shorebirds and resident species AMOY breeding distribution: (Sanders et al. 2008)

RESEARCH WITHIN THE CAPE ROMAIN REGION Reproductive success can be low and highly variable among years (Thibault 2008) Two major factors negatively affecting reproductive success flooding (boat wakes, high tides) predation

LOSS OF PRODUCTIVITY Important to determine when productivity is lost Egg laying, incubation, chick-rearing, post-fledge Prior information indicated loss during incubation and possibly chick-rearing Headstarting Collecting designated clutches during stage of vulnerability (incubation) Incubating clutch in a controlled setting Returning chicks to nest immediately after hatch NOT captive-rearing! Since this species is declining in states south of Virginia and studies have found this is due to poor reproductive success… Need to determine life phase is most sensitive during the breeding season

GOALS OF STUDY Examine reproductive ecology of AMOY in a core portion of their breeding range Assess methods to improve nesting success of AMOY

Study Objectives Measure reproductive success of AMOY nesting within the Cape Romain Region Identify and quantify factors affecting nest survival in oystercatchers Determine whether or not headstarting improves hatch and fledge success

Atlantic Intracoastal Waterway Primary Study Areas Shell rakes along the Atlantic Intracoastal Waterway (AICW) from marker 67-97 Shell rakes in Southwest Bulls Bay (SWBB) from Venning Creek to Bulls Creek Southwest Bulls Bay Atlantic Intracoastal Waterway

Nest Monitoring Shell rakes searched and nests checked every 4 days on average (range 0-10 days) Overwash cups placed ~1m from scrape Cameras set up on control nests in SWBB in 2011 All nests monitored until failed or successful (chicks fledged)

HEADSTARTING METHODS Collect partial clutches from every other nest Label eggs to identify site and nest number Fake wooden eggs secured in scrape Leave one real egg in nest scrape Place collected eggs in cabinet incubator (37.4C, 60% RH) Chicks returned to nest after hatch Verify adults accept chick

NEST FATE DURING INCUBATION Hatched – Nest hatches at least one egg or chick returned successfully to nest (headstart) Undetermined – No sign of predation or overwash Overwashed –Evidence of overwash, e.g. salt water in cup, debris, wrack, fake eggs buried Depredated – Predation signs such as bite marks, scat, tracks, or video evidence Abandoned – Not observed incubating for 3 visits and egg feels hot/cold/wet or new nest found Failure to hatch – No sign of hatch two visits after anticipated hatch date Nests found during incubation ultimately either hatched or failed due to overwash, predation, abandonment, failure to hatch and undetermined causes. Here I give the definitions of each category and the field signs associated with each.

METHODS - CHICK SURVIVAL 1.3g transmitters attached to chicks Chicks located and measured ~4 days Chicks were considered “fledged” at 35 days or when observed in flight AMOY chicks camouflage into environment and are highly mobile = difficult to monitor for fledge success Attached 1.3g transmitters to newly hatched headstarted chicks before returning them to the nest

DATA ANALYSIS Modeled daily survival rate during incubation using three logistic-exposure models in SAS (PROC GENMOD) Control nests only Headstart and control nests Headstart nests only Goodness of fit assessed by deviance/df: <1 indicates good fit Odds ratios Apparent success, DSR and probabilities of survival for nests during incubation and chick rearing (Mayfield) PROC GENMOD- this looks at intervals of survival throughout nesting cycle rather than overall nest success

RESULTS Total # nests monitored during incubation: Headstart n=83 Control n= 90 Total # nests monitored during chick rearing: Headstart n=44 Control n=10 Nests monitored at intervals of 4 days or less for 94% checks (longest interval between checks = 8 days) Chicks monitored at intervals of 4 days or less for 91% of checks (longest interval between checks = 10days) Nest monitoring period: April 5, 2010 – August 2, 2010 April 4, 2011 – August 1, 2011 For this two year study, we monitored a total of 83 headstart nests and 90 control nests during incubation and 44 headstart nests and 10 control nests during chick rearing

NEST FATES Control Headstart Determined nest fates for control and headstart nests and found that: Lower proportion of control nests hatch compared to headstart Higher proportions of depredation, overwash and unknown failures for control nests SWBB 2011 very high proportion of depredated nests which was determined through the use of camera surveillance

INCUBATION RESULTS This table gives Mayfield survival estimates for hs and c nests for all sites and years Notice two things: 1- Headstart nests have higher apparent success, Mayfield daily survival and probability of success compared to control nests for all sites and all years 2 – Less exposure days and more failures for all control nests compared to headstart nests for all sites and years a calculated as # successful nests (hatch >= 1 egg)/ #nests monitored b calculated as # losses/total exposure days c calculated as Mayfield DSR^ number of days in the incubation stage (27)

HATCH SUCCESS OF HEADSTART NESTS “Take eggs” are eggs collected for incubation Notice: very low occurrence of left eggs hatching (only one hatches per site, if at all). Also notice high percentages of take eggs hatching – higher success in year two because of adjustments to incubator settings. Nests that were not incubated until hatch but had chicks hatch out in incubator were fostered into another nest. a does not include nests that did not have a leave egg (clutch size of 1 egg) b does not include nests that failed before collection

CONTROL MODEL HEADSTART MODEL AICW 2010 (p value 0.004) Hightide (p value 0.02) Day in nest cycle (p value 0.09) Odds ratios: A control nest along the AICW in 2010 is 2.76X more likely to survive than a nest in SWBB in 2011 For every unit decrease in the height of high tide, a nest is 1.9X more likely to survive For each increase in the day in the nest cycle a nest is 1.03X more likely to survive HEADSTART MODEL None of the variables had significant effects on nest survival

HEADSTART AND CONTROL MODEL Headstart (p value <0.0001) Day in the nest cycle (p value 0.05) AICW 2010 (p value 0.07) Odds ratios: A headstart nest is 3.3X more likely to survive than a control nest For each increase in the day in the nest cycle a nest is 1.03X more likely to survive A nest along the AICW in 2010 is 1.65X more likely to survive than a nest from SWBB in 2011

FLEDGE SUCCESS The following table reports fledge success for headstart and control nests for all sites and years Notice things: 1)Fledge success low and highly variable within and between sites and years 2) Few control nests in sample due to poor hatching success Identifiable causes of death for these chicks included predation, exposure, killed by adults, and overwash Transmitters from chicks taken by predators were recovered near mink scat, as well as mink dens. Ex – one transmitter found in front of mink den where we observed a mink with two kits. a calculated as # successful nests (fledge >= 1 chick)/ # nests monitored b calculated as # losses/total exposure days c calculated as Mayfield DSR^ number of days in the pre-fledge stage (35)

DISCUSSION Headstart nests more likely to survive than control nests Headstart nest survival not affected by variables Control nest survival highest along AICW in 2010 Increased likelihood of nest failure of control nests due to overwash during high tides From these results, we found that….

HEADSTARTING CONCLUSIONS * Nest success enhanced via headstarting but fledge success can still be low and variable due in large part to predation at this sites during these years Useful in areas where egg loss is high and chick loss is low Overwash as primary cause of nest loss Nest failure due to human disturbance Predators depredating eggs only Effective in combination with trapping efforts 9 mink removed pre-laying behind shell rake in SWBB 2011– coincident with fledging of two headstarted chicks despite attempted depredation of fake eggs by raccoon In this slide you Bring together Nest + Fledge Success

CONCERNS IS THIS PERPETUATING AN ECOLOGICAL TRAP? MAYBE, but… if we can reduce nest loss by headstarting and reduce chick loss through management then maybe we can change a sink/trap into a source.

Acknowledgements Funding and Material Support National Fish and Wildlife Foundation US Geological Survey Cooperative Research Unit SC Department of Natural Resources Clemson University School of Agricultural, Forest and Environmental Sciences US Fish and Wildlife Service – Cape Romain National Wildlife Refuge Field and Logistical Support Mark Spinks, Sarah Dawsey, Billy Shaw, Sarah Woodward, Adam DiNuovo

Questions?