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Home , American black duck, Black Duck Joint Venture, High marsh, Inner Banks, Low marsh

Co-Authors

Doug Howell, Waterfowl Biologist

North Carolina Wildlife Resources Commission

Wildlife Management Division

Surveys and Research Program

Joe Fuller, Migratory Game Coordinator

North Carolina Wildlife Resources Commission

Wildlife Management Division

Surveys and Research Program

Roald Stander, M.S. Student

University of

Department of Environment and Geography

Master of Environment Program

Special Thanks! – You are viewing this document because you have played an integral role in insuring this project’s successful fruition. Whether you are a property owner, research advisor, local wildlife professional, project sponsor, or simply a helping hand, your help does not go unnoticed. I would like to thank every person involved.

- Daniel Lawson Graduate Research Assistant

Lawson 1

Background platyrhynchos) during the breeding and wintering periods (Anderson et al. 1987, Conroy The American black ( rupripes) et al. 2002). The historical loss of coastal population has been in decline since the 1950s. in the Mid-Atlantic region has been According to United States and Wildlife Service (USFWS) mid-winter survey estimates, significant (Dahl 1990) and their continued black duck numbers decreased more than 50% degradation (Tiner 1987, Dahl 2000, Dahl 2006, from the 1950s to the 1990s (Figure 1) (USFWS Stedman and Dahl 2008, Dahl and Stedman 2017). Since this time, the black duck population 2013) may limit the ability of this area to support has stabilized in the Atlantic Flyway (Figure 2). black duck populations at conservation goals (Morton et al. 1998, NAWMP 2014). Mid-winter Survey for American Black (1955-2015) Although there have been ongoing efforts to understand the limiting factors of Mid-Atlantic black ducks during the nonbreeding season (Cramer et al. 2012, Livolsi 2015, Ringelman et al. 2015), there is a need to better understand the breeding season limiting factors as well, especially in light of analyses that suggest long- term declines in recruitment (Brook 2006). Consequently, the has determined that there is a need to quantify regional differences and factors influencing Figure 1: USFWS Mid-winter Waterfowl Survey Estimates black duck productivity. for the in the Atlantic and Mississippi Flyways (1955-2015) Black ducks breed in highest concentrations in the eastern Canadian provinces (Rusch et al. 1989), and nesting studies in this region generally have found nest success is adequate to maintain the population and is similar to sympatric (Petrie et al. 2000). A smaller population of black ducks nest in the Mid- Atlantic region, however less is known about their nest success. Until recently, the status of the breeding black duck population in North Carolina was poorly understood. North Carolina represents the southern extent of the ’ breeding range (Stewart 1958, Parnell & Quay

1962, Bellrose 1980). Although breeding black Figure 2: USFWS Mid-winter Waterfowl Survey Estimates ducks in North Carolina are well documented, for the American Black Duck in the Atlantic Flyway (1990- 2015) their long-term population trend and nesting success is unknown. We suspect that breeding There are several potential explanations for populations have declined over time, similar to this decline, including loss in the quantity and breeding populations farther north in quality of breeding and wintering habitats, and Maryland (Costanzo and Hindman 2007), overharvest, and interactions (competition, hybridization) with mallards (Anas Lawson 2

but there is no empirical or baseline data to Proposed Research support this. As per research objective request from the There have been a few past attempts to Black Duck Joint Venture, NCWRC along with the quantify the status of breeding black ducks in University of Delaware Department of North Carolina; however, these were spatially Entomology and Wildlife Ecology (UDel) initiated limited. Parnell and Quay (1962) reported black a project that would quantify the breeding effort duck production between 1938-1958 on Pea of the American black duck in coastal North Island, North Carolina and conducted more Carolina. Specifically, it is our (NCWRC and UDel) thorough nest searching and nest success goal to estimate reproductive parameters of research in 1959-1960. They found black duck breeding black ducks in coastal habitat in North nesting was beginning to decline and noticed Carolina as a function of nesting habitat quality, lower apparent nest success (69%) than those human disturbance, predation, flooding, and observed in the Chesapeake Bay (91%) or burning. (81%) (Stotts 1956, Wright 1954). Breeding Black Duck Survey 2017 Additional research in 1990 (Fleming et al. 2000) on Piney Island, North Carolina located 12 nests Introduction: The North Carolina Wildlife with an apparent nest success of only 67%. In Resources Commission Breeding Black Duck 2013, the North Carolina Wildlife Resources Survey conducted in 2017 is built upon surveys Commission (NCWRC) initiated an aerial black conducted each year since 2013. Since the pilot duck population survey to better understand the survey in 2013, NCWRC has developed a method distribution and density of breeding black ducks to index the breeding black duck population in in suitable coastal marsh habitat in North suitable coastal marsh habitat in North Carolina. Carolina (NCWRC unpublished data). This survey is based upon the Atlantic Flyway Breeding Results: This year 131 of 135 randomly chosen Waterfowl Plot Survey (AFPS; Heusmann and 1-km² plots were surveyed in three days, April 9- Sauer 2000). During 2013-2016, the 11, 2017. Three were not surveyed due to methodology and survey area was refined to restricted airspace at the Dare County Bombing produce more precise breeding population Range and one plot could not be surveyed due to estimates. In 2016, the sampling frame residential development. The survey team contained 1,267 1-km² plots containing between counted 158 total black ducks. Per Atlantic 5-40% marsh habitat, and 595 plots containing Flyway Plot Survey (AFPS) protocols, this >40% marsh habitat which was deemed suitable represented 75 indicated pairs (IP) (Table 1). for nesting black ducks. Of these plots, a Table 1: Group Size of Observed Black Ducks, April 2017. randomly sampled subset of 134 plots was surveyed via helicopter. Extrapolating the results Group Size Number of Observations 1 29 of the survey of this subset of plots to the 2 36 entirety of North Carolina coastal marsh habitat, 3 3 results in an estimate of 2,404 (90% CI = 1,131- ≥4 3 3,678) total black ducks and 694 (90% CI = 500- 888) nesting pairs. However, there is no Mean counts of indicated pairs (IP's) of black knowledge about their nest success and the ducks were highest in plots containing >40% factors that could influence those values. marsh. However, plots containing 5-40% marsh contributed 44% of the total IP estimate due to the large number of plots in this survey stratum. Lawson 3

The total population estimate included 1,048 IP's and 2,270 total indicated (TIB) (Table 2).

Table 2: Population estimates of black ducks by survey strata in coastal North Carolina, April 2017.

Stratum No. of Plots Total No. Total Indicated Estimated Estimated Total Surveyed of Plots Pairs/ Plot Indicated Pairs Indicated Birds Plots with >40% Marsh 44 595 0.98 581 (293-870) 1,163 (586-1,740) Plots with 5%-40% Marsh 88 1,267 0.37 466 (251-681) 1,107 (574-1,639) Total Survey Area 131 1,862 - 1,048 (706-1,389) 2,270 (1,520-3,019)

Discussion: This survey represents the 5th year estimates, both positively and negatively. For of a multi-year effort to develop an aerial survey example, groups of three black ducks were to estimate the size of the breeding black duck treated as two IP’s. If these three black ducks population in suitable coastal marsh habitat in were identified as three drakes, they would have North Carolina. Since no changes were made to been treated as three IP’s. Alternatively, the survey design in 2017, only results from 2016 observations of single black ducks were counted and 2017 surveys are directly comparable. as one IP. However, some portion of the single Although the estimate of IP's increased black ducks observed were likely hens disturbed considerably from 2016, the 90% confidence from their nest. In 2017, the survey team was intervals overlap, suggesting that increases may able to positively identify one hen flushing from in part be related to sampling error. a nest and did not include this observation as an Interestingly, TIB's in 2017 was very similar to IP. 2016. Total indicated birds is influenced by NC American Black Duck Nesting Study observations of grouped black ducks (>4 observed). Grouped black ducks may represent Introduction: The North Carolina Wildlife migrant black ducks that have not left the state Resources Commission and the UDel coordinate or local, nonbreeding birds (during the survey the American black duck breeding ecology study. window). Previous modifications to survey This year we conducted nest searches for design have been made with the goal of reducing incubating black ducks on six 100 m2 study sites standard errors of survey estimates. Due to in coastal North Carolina. We monitored these three plots having an outlier number of IP's nests at seven-day intervals until they were observed, standard error increased considerably terminated (hatched, depredated, flooded, etc.). from 2016 (SE=110) to 2017 (SE=205). Moving Vegetation measurements were then taken at forward, there is likely no way around this issue nest termination. A select number of nests were apart from adding additional survey plots. additionally monitored via trail camera in hopes to better record causes of nest failure and to The inability to determine the sex of any synthesize an incubation break chronology for observed black ducks from the air introduces black ducks in the southern Atlantic Flyway. some bias into the estimate of IP’s and TIB’s. Per Further, we collaborated with Delta Waterfowl AFPS protocols, a conservative approach was Foundation to test the efficacy of nest searching used when recording groups of black ducks of with aerial drones employing thermal imaging unknown sex. The inability to distinguish the sex cameras. of black ducks has the potential to influence IP Lawson 4

Nest Searching: Although there have been a few borders wetlands), islands, and tidal brackish previous attempts to quantify the breeding marsh. Further, we chose six focal areas that status of black ducks in coastal North Carolina contained these habitats and, per the NCWRC (Parnell & Quay 1962, Fleming et al. 2000), there breeding black duck surveys, breeding black were not any datasets available that identified duck pairs. For the sake of logistics, we placed optimal black duck nesting habitat in this region. four sites northeast of the Pamlico mouth To determine how and where to search for these along the of the Pamlico Sound nests, we drew from studies conducted farther stretching to the intersection of US 64 and the north, in the Chesapeake Bay region (Krementz Croatan Sound (Figure 3). We placed two study 1991, Costanzo and Hindman 2007, Haramis sites encompassing parts of Pea Island and 1996, Stotts and Davis 1960). Based on our on the of North findings, we decided to focus on three habitat Carolina (Figure 4). types: upland buffers (upland habitat that

Figure 3: Inner Banks Study Sites. Hyde and Dare Counties, North Carolina

Figure 4: Outer Banks Study Sites. Dare County, North Carolina Lawson 5

Our nest searching technique was modified from all-terrain vehicle (atv) chain drags used for locating upland nesting waterfowl (Klett et. al. 1986), where a chain suspended between two atvs is pulled across standing vegetation. The chain covers all vegetation in between the atvs and chain links rattle to produce a metallic sound that causes nesting hens to flush as the atvs progress forward. Since our study sites were not accessible to atvs, we decided to modify the dragging apparatus so it could be used by two technicians on foot. Nylon rope seemed to be the most sensible alternative. We used 100 ft. Figure 5: Nest Dragging in North Carolina lengths of rope and attached aluminum cans We initiated nest searching on April 1ST and spaced at ~2m intervals along the entire length continued until June 17th. During that time we of the rope. Every can received small (~3-4 cm) found our nest dragging technique to be a great rocks to serve as noisemakers in lieu of shifting success and almost necessary to find the chain links. Two technicians conducted nest sparsely positioned black duck nests in the many drags. One technician would stretch the rope to thousands of acres of coastal that the edge of a , typically on the edge of a were surveyed. This season we found and body of water. The other technician would monitored a total of 56 duck nests. The majority stretch the other end of the rope directly inland of nests were black duck (n=47, 84%). from the wetland edge. Once the rope was and (Mareca strepera) made up the extended, both technicians traveled forward remaining nests at 4 (7%) and 5 (9%), while remaining parallel to one another and the respectively (Figure 6). wetland edge (Figure 5). An additional technician was used as a spotter that constantly watched the dragline to identify flushing hens. The spotter would identify the exact location of the flushing hen and guide the other technicians to the nest. Technicians continued forward until a hen was flushed. Once a hen was flushed, one technician would approach the nest and begin data collection while the other stayed at least 5 meters away and recorded data. In areas where we could not drag the rope due to vegetation height and rigidity, technicians distanced themselves 5–25m apart and walked transects of the selected area. We utilized this technique Figure 6: 2017 Nests Species Composition specifically on spoil islands in the Pea and The inner banks study areas (Figure 3) Roanoke Island study sites (Figure 4). contained mostly brackish marsh and upland buffer habitat. We found 55% (n=31) of the nests in these areas. The remaining 45% of nests Lawson 6

(n=25) came from the island habitats of the outer banks.

American black ducks favored nesting on the slightly elevated beach ridges of the inner banks’ brackish marsh. Beach ridges were slightly higher than the adjacent because of sand deposition due to years of wave action. These ridges were directly adjacent to the open water of back bays and points jutting into the sound. The dominant plant species on the brackish marsh beach ridges () were: black needlerush (Juncus roemerianus), salt- marsh cord grass (Spartina alterniflora), salt- meadow cord grass (Spartina patens), and saltgrass (Distichlis spicata). These species made up the high marsh, with each species dominating in patches or zones to form a mosaic vegetation Figure 8: High Marsh Dominated by Spartina patens pattern (Figures 7 - 8). On our two Outer Banks study sites (Roanoke Island and Pea Island) we spent a great majority of our time searching natural and man-made islands within the Pamlico Sound. These islands proved to be very diverse in topography, vegetation structure and composition, and black duck nesting productivity. Topography reflected how the island was formed, whereas vegetation structure and productivity reflected how long ago. Man-made (dredge islands) where typically elevated and contained an array of plant communities (Figures 9 - 10). Some of which were: dune grasslands, maritime shrublands, upper and lower beach, and maritime vine tangles. Typically, the older the island, the later the successional stage. Naturally formed islands were low lying and were broadly classified as brackish marsh. As mentioned earlier, each island had unique black duck nesting productivity. Most of the variability was attributed to predator influence and vegetation structure. Figure 7: Brackish High Marsh Mosaic Lawson 7

Figure 9: Man-made Dredge Island > 10 Years Old

Figure 11: Elevated Black Duck Nest in Brackish Marsh

Figure 10: Man-made Dredge Island < 10 Years Old

Collectively, nests were located an average of 25.6 meters from open water. Nests located in flood prone spots, brackish marsh especially, were slightly elevated (15-30 cm) structures that consisted of needlerush or Spartina spp. leaves Figure 12: Low-Profile Black Duck Nest in Brackish Marsh (Figure 11) and resembled overwater-nesting diving duck nests. Nests in the brackish marsh On islands in the Outer Banks study sites, black that were not elevated, were tucked deep into duck nests were located within dense vegetation surrounding cover (Spartina patens, Distichlis in any combination of warm season grasses, spicata, and Juncus roemerianus) and the bowl Rubus, and forbs (Figures 13 - 14). was low in profile and mainly constructed of Spartina patens (Figure 12). Both varieties had down lining the nest bowl, but a profuse lining seemed to be less common in elevated structures. Lawson 8

maximum average vegetation height. We found percent composition at the microhabitat scale to be; 65% grass, 14% litter, 7% forbs, 5% woody vegetation, 5% water, and 4% bare soil. Our average VOR was 0.5 meters meaning there was more than 50% visual coverage by vegetation below that height. Finally, max average vegetation height yielded 0.9 meters.

Earliest and latest nesting initiation, peak(s) of nesting initiation, and nesting season duration are questions that have never been confidently answered of black ducks nesting in coastal North Carolina. Foremost, we estimated nesting Figure 13: Black Duck Nest in Pioneer Island Vegetation initiation questions by backdating to the initiation date (the day the first egg was laid). We did this by adding the number of eggs in the nest to the incubation stage in days, and then took the sum and subtracted it from the date we discovered the nest. Nesting season was simply the date the first nest of the season was initiated until the final nest was terminated. The earliest date we found black ducks initiating nests was March 3; the latest date was May 24 (Figure 15). This year we noticed two separate nest initiation peaks. The first was during the first two weeks of April (4/2 - 4/15). The second peak was over the

first two weeks of May (4/30 – 5/13). One Figure 14: Black Duck Nest in Dense Island Vegetation possible explanation for the separate peaks is an We took vegetation measurements at nest inclement weather event that occurred in mid- sites once nests were fated (e.g. abandoned, late April. During this time, several flood events depredated, etc.). We hoped to get an idea of caused a high rate of nest failure in brackish the exact microhabitat black ducks chose for marsh adjacent to the Pamlico Sound. A few of nesting in North Carolina. To achieve this, our monitored nests remained under water for technicians collected percent composition with a an extended period of time. It is possible that Daubenmire frame and Visual Obstruction the peak at the beginning of May could have Readings (VOR’s) with a Robel pole (Robel et al. been a renesting effort. 1970). Along with the VOR’s, we recorded Lawson 9

Figure 15: 2017 Black Duck Nest Initiation Chronology

Nest Monitoring: This season we monitored 47 related to the nest (i.e. hen present, eggs warm black duck nests at 7-10 day intervals (Klett et al. and covered, eggs cold and uncovered, etc.). 1986). The product of our monitoring efforts Along with collecting this data, we covered the allowed us to have several exposure days to nest with down and other present nest bowl insure that our incubation stage estimates were materials and then made a distinct “X” on top accurate. Multiple visits also insured more with two pieces of contrasting vegetation. precise nest fates, because it reduced the time Likewise, we used the progression of embryo terminated nests were exposed to the elements. development to determine if the hen was still The composition of nest fates for the 2017 season are as follows in (Table 3). actively incubating the nest. There were several factors we identified that caused hens to Table 3: 2017 Nest Fate Composition abandon nests. (Figure 16). Fate Black Duck Nests Hatch 9 Abandoned 21 Depredated 12 Nonviable 3 Unknown 2

We identified hatched nests according to (Klett et al. 1986). In the nest, we looked for presence of detached shell membranes and yellowish feather sheaths or small egg fragments without membranes in nest material, or presence of Figure 16: 2017 Nest Abandonment Causes ducklings in the nest bowl. Identifying The factor that attributed most to nest abandoned nests was a little bit trickier. On abandonment was unfortunately, our own initial initial nest visits, we noted the hen status as it Lawson 10

activity at the nest site. Of this percentage, all nests were still in lay or very early in incubation (< 7days). Of the twelve depredated nests, we identified several nest predators. Nest predators identified included American and fish crow (Corvus brachyrhynchos and Corvus ossifragus, respectively), bald eagle (Haliaeetus leucocephalus), (Procyon lotor), American mink (Neovison vison), and red imported fire ant (Solenopsis invicta). Nonviable nests were nests where all eggs addled before any other fate. To aid in fating nests, we placed Figure 18: Black Duck Hen Elevating Nest Bowl Prior to trail cameras on 35 black duck nests. High-water Event

Trail Cameras: Placing trail cameras on nests helped us to understand the nesting ecology of the black duck in North Carolina. By formatting cameras to capture images every minute, we were able to record the frequency and duration of incubation breaks. Cameras captured many events that had an impact on the nest fate. Some of these events included: flooding, depredation, prolonged incubation breaks, and abandonment. Sample trail camera photos are pictured in (Figures 17-20). Figure 19: Bald Eagle Depredation

Figure 17: April 25 Flooding Event with Submerged Black Figure 20: Raccoon Depredation Duck Nest Pictured in Top-center

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Collaborative Drone Research birds, in that targets observed three nights in a row would be indicative a nesting bird. Flying three nights was not achieved at all sites due to inclement weather. All of the sites that we visited had a relatively low number of known nests.

The thermal camera does not detect heat signatures, but rather detects relative temperature differences. When the habitat

being surveyed is of a homogenous Figure 21: Delta Waterfowl Research Drone temperature, detectability is very high. The avian thermal targets are the hottest objects Introduction: This year we had the opportunity within the field of view (FOV) of the camera and to collaborate with Delta Waterfowl Foundation typically show up clearly. and the University of Manitoba on research testing the efficacy of thermal-imagery equipped Discussion: Surveying coastal regions provides drones in avian nest searching. Due to the unique challenges due to the humid sparseness of black duck nests within the conditions. Black ducks in the region typically brackish marsh of coastal North Carolina, we saw select salt marsh hay grass (Spartina patens) as this as an opportunity to increase our nest nesting cover. The structure of the grass seems searching capacity while contributing to drone- to inherently hold moisture due to the c-shaped based wildlife sampling research. Roald Stander, structure of the blade. The high levels of low- the drone research graduate student with lying humidity seems to be exacerbated by the University of Manitoba, brought his research to fact that this is a tidal area. our study sites May 24-30. Despite all the challenges, we located 2/2 Results: We chose study plots 10 – 40 acres in known black duck nests and 14 Clapper rail size that contained known active black duck nests. The known nests were relatively open nests. We surveyed sites between midnight and from above, and the rail nests were located in sunrise. Detectability of the thermal targets by black needlerush. One of the two active black the thermal camera varied from site to site; on duck nests included in the survey was extremely the same site over multiple days; or even on the visible from 150 meters (Figure 22) using a same site during a single survey. Different transect-based survey method. We were able to habitats had certain physical characteristics hover over the nest at a relatively low height, <5 which increased/decreased the likelihood of meters, without causing the hen to flush (Figure detecting the targets. Certain meteorological 24). conditions seemed to greatly influence detectability. Humidity ultimately negatively We noticed a raccoon momentarily disappear influenced detectability. Thermal reflectance as it was moving through matted patches of from moonlight was also observed. vegetation, including Spartina patens. This prompted us to test the detectability of a hot Our goal was to three successional missions thermal target (>60⁰C) placed in typical nesting over different nights recording coordinates of cover. The thermal camera could only detect each target. The aim of flying multiple times the target at 7’ AGL. over the same area was to rule out transient Lawson 12

The habitat inherently had challenges associated with working in tidal areas. The observed detectability warrants further testing. Although we found all known nests, the results were inconclusive.

Figure 22: Nesting Black Duck Thermal Imaging Snapshot from 150 meters

Figure 23: Nesting Black Duck Thermal Imaging Snapshot from 50 meters

Figure 23: Nesting Black Duck Thermal Imaging Snapshot from <5 meters

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