Occurrence, Distribution and Reproductive Status of Female Bottlenose Dolphins (Tursiops Truncatus) in Roanoke Sound, NC

Occurrence, Distribution and Reproductive Status of Female Bottlenose Dolphins (Tursiops truncatus) in Roanoke Sound, NC

By Waverly Reibel

Dr. Andrew J. Read, Advisor

April 23rd, 2020

Master’s Project submitted in partial fulfillment of the requirements for the Master of Environmental Management degree in the Nicholas School of the Environment of Duke University.

Executive Summary

I examined the spatial distribution of bottlenose dolphin (Tursiops truncatus) nursery groups in Roanoke Sound, NC, to gain insight into how environmental parameters affect site fidelity, and to determine whether habitat use patterns change based on the reproductive state of females. I performed a home range analysis of mature females and compiled information on interbirth intervals and length of calf dependency to obtain a more comprehensive picture of the ecology and life history of this age and sex class of estuarine dolphins. I analyzed photo- identification survey data from Roanoke Sound collected over 11 years (2008-2019) to determine core usage areas of female bottlenose dolphins with respect to reproductive state. I compared the location and extent of kernel density estimates of home ranges for nursery groups and non- nursery groups. Many nursery groups are observed in this area during spring and summer, leading to the hypothesis that Roanoke Sound is an important nursery habitat. The importance of this area to lactating females may be attributable to its relatively shallow depth and abundant seagrass beds, which provide protection and a relatively plentiful supply of prey. In Roanoke Sound, nursery groups (n = 170) were significantly (p < 0.00001) larger than non-nursery groups (n = 68) with a mean of 12 individuals per sighting, while non-nursery groups had an average group size of 4 individuals. Nursery groups and non-nursery groups had a high overlap percentage between their ranging patterns, with core areas overlapping 57% and home ranges overlapping 88%. This demonstrates that there is no specific “nursery area” within the Roanoke Sound, but coupled with the high numbers of large nursery groups sighted during the summer, the entire site itself may be of importance to these females. Four focal females had a mean interbirth interval of 7.5 years, and a mean length of calf dependency of 4.75 years. The females exhibited individual variation in ranging patterns, with habitat use overlap percentages between nursery and non-nursery areas ranging from 11-79%. These females may be choosing areas based on their needs (and those of their calves), either for energetic purposes or protection. Documentation of nursery habitat can aid protection of these important areas through implementation of measures such as safe boating zones and increased water quality monitoring, as well as assist in the development of policies and educational materials to reduce anthropogenic sources of mortality in the population.

Table of Contents

1. Introduction ...... 1 1.1 Northern North Carolina Estuarine System Stock ...... 1 1.2 Nursery Groups and Roanoke Sound, NC ...... 2 1.3 FB717 Case Study ...... 3

2. Objectives ...... 5 2.1 Client ...... 5 2.2 Project Purpose ...... 5

3. Methods ...... 5 3.1 Data Collection and Preparation ...... 5 3.2 Preliminary Analysis ...... 7 3.3 Spatial Analysis ...... 8

4. Results ...... 9 4.1 Group Results ...... 9 4.1.1 Group Size Results ...... 9 4.1.2 Spatial Results ...... 11 4.2 Individual Female Results ...... 12 4.2.1 Interbirth Intervals and Calf Dependency ...... 12 4.2.2 Spatial Results ...... 12

5. Discussion ...... 16 5.1 Nursery Groups ...... 16 5.2 Individual Females ...... 16 5.3 Management and Research Recommendations ...... 17 5.4 Limitations and Future Research ...... 18

6. Acknowledgements ...... 18

7. Works Cited ...... 19

8. Appendix ...... 21 A1. Spatial Analysis ArcPro Model Example ...... 21 A2. Spatial Analysis Reference Data ...... 21 A3. Map of Annual Group Spatial Results ...... 22 A4. Chart of Annual Group Spatial Results ...... 24 A5. Map of Seasonal Group Spatial Results ...... 25 A6. Chart of Seasonal Group Spatial Results ...... 25 1

1. Introduction 1.1 Northern North Carolina Estuarine System Stock The community of bottlenose dolphins (Tursiops truncatus) that frequent the northern estuarine systems of North Carolina belong to the Northern North Carolina Estuarine System Stock, or the NNCESS. As defined by the Marine Mammal Protection Act, a “stock” is a species or subspecies with a similar spatial distribution which interbreeds when mature [16 U.S.C. 1362A]. These dolphins are commonly sighted on the western side of the Outer Banks’ barrier islands, in the bays, estuaries and sounds. The NNCESS exhibits seasonal movements, perhaps as a response to changes in water temperature and prey migrations, and their range extends from the New River, NC to Virginia Beach (Waring et al. 2018). During the cold-water months, most of the stock is found between the New River and Cape Hatteras, NC. In the warm-water months, some animals from the NNCESS are sighted further north in the Pamlico Sound system, which include the Core Sound, Roanoke Sound and Albemarle Sounds. The most recent population estimate for this stock is 823 individuals, based upon a 2013 photo-identification mark-recapture study performed by Gorgone et al. (2014). The NNCESS is considered strategic under the Marine Mammal Protection Act because human-caused mortality likely exceeds its Potential Biological Removal (PBR). The calculation of annual human-related mortality, almost all of which is due to by-catch in commercial gillnet fisheries, between 2011-2015 ranged between 0.8 and 18.2, but these values are biased low due to a lack of fisheries observer coverage and the difficulty of assigning by-catch mortality to specific stocks along the south-eastern coast (Waring et al. 2018). From 2011-2015, 73 dolphins assigned to the Northern North Carolina Estuarine System Stock stranded with evidence of human interaction (Waring et al. 2018). However, it is estimated that less than one-third of dolphin estuarine carcasses are recovered, so this number may be negatively biased (Wells et al. 2015). The NNCESS interacts with at least nine different commercial gear types, including gillnet, long haul seine, pound net and crab pot trap fisheries. One of the most recent interactions occurred in the Roanoke Sound, NC, where a crab pot was entangled around the fluke of a dolphin in October 2018 (Figure 1A). Four of the 73 recovered dolphins exhibited signs of a boat strike and, in Roanoke Sound, NC, photo-identification studies have documented recent boat propeller injuries on the local dolphin population (Figure 1B). This stock is also exposed to a variety of persistent environmental pollutants that can originate from 2 both agricultural and urban runoff and can inhibit reproduction in the species (Schwacke et al. 2002). In 2004, Hansen and colleagues tested the blubber of 47 common bottlenose dolphins in Beaufort, NC, and discovered elevated levels of DDTs and PCBs (Hansen et al. 2004). Marine debris can also impact the NNCESS due to their range’s proximity to coastal cities, including the recent example of a calf in 2015 encompassed in a Frisbee ring (Figure 1C).

1.2 Nursery Groups and the Roanoke Sound, NC Nursery groups of bottlenose dolphins contain mother-calf pairs and can act as both and Mann, 2008). During the peak birthing period of spring and early summer, many nursery groups are observed in the Roanoke Sound, NC (Thayer, 2003). The importance of the sound as a nursery habitat to lactating females may be attributable, at least in part, to its relatively shallow depth, an average of 3.5 feet deep, and abundant seagrass beds. Dolphin calves are small, have relatively poor survival skills and a strong dependence upon their mother. Nursery groups can act as protective units for the vulnerable young and often utilize shallow areas to minimize interactions with sharks, boats or aggressive males. For example, nursery groups of dusky dolphins (Lagenorhynchus obscurus) have been shown to prefer shallow, nearshore habitats, away from their predators, which occurred exclusively in deeper waters (Weir et al. 2008). Warm waters, such as those in the Roanoke Sound in the summer, may also improve chances of survival for neonates due to the presence of fewer predators (Whitehead and Mann, 2000). Bottlenose dolphin nursery areas may include seagrass beds due to the abundance and diversity of prey species that inhabit seagrass habitats. Lactating mothers have 50% higher 3 caloric intake than pregnant dolphins, reflecting high energy demands (Whitehead and Mann, 2000). The diets of estuarine dolphins in NC are dominated by Atlantic Croaker (Micropogonias undulatus) and spot (Leiostomus xanthurus). Both species are abundant in estuarine systems during the summer and fall (Gannon and Waples, 2004). This abundance of soniferous fish may contribute to the high density of dolphin nursery groups in the Roanoke Sound.

1.3 FB717 Case Study FB717 serves as an excellent example of the typical ranging patterns and behaviors of female dolphins of the Northern North Carolina Estuarine System Stock. Information on FB717 was gathered from six contributors to the Mid-Atlantic Bottlenose Dolphin Catalogue (MABDC): Duke University Marine Lab, North Carolina Maritime Museum, HDR Inc., North Carolina Division of Marine Fisheries, Outer Banks Center for Dolphin Research and the Nags Head Dolphin Watch. FB717 was sighted 89 times from 1995-2019, including her first record, when she was captured during a health assessment. “Freeze-Brand 717” received her name when she was tagged and freeze-branded on July 15th, 1995 in the Bogue Sound. She received a roto- tag on the dorsal fin, as well as a freeze-brand of the number “717” on her dorsal fin and body (Figure 2A, 2B). When captured, she weighed 222 pounds and measured 206 centimeters long, indicating that she was about 2 years old at this time (Read et al. 1993). The team took samples of blood, feces, urine, blubber, and made acoustic recordings, as well as body measurements.

FB717 reached sexual maturity around 2003, became pregnant in the spring of 2004, and had her first calf in May 2005 in Beaufort, NC. She has now had five calves, with the most recent being born in 2018. FB717 was last sighted as a 26-year-old in the summer of 2019, with her year-old calf, in Roanoke Sound, NC (Figure 2C). Based on the durations of association, 4 most of her calves were successful. Each calf was sighted with her for between 3-5 years. However, she did have a calf in 2017 and lost it that year due to unknown circumstances. Typical of many dolphins of this stock, FB717 generally spends her fall and winters near Beaufort, NC. In the spring and summer, she is most often sighted with her calves in Roanoke Sound, NC (Figure 3). Four out of six of her calves were seen with her in the Roanoke Sound, showing the importance of this area to mature females of the NNCESS.

2. Objectives 2.1 Client The Outer Banks Center for Dolphin Research (OBXCDR) was created in 2008 with the mission to promote the conservation of bottlenose dolphins through research and education of the Northern North Carolina Estuarine System Stock. The OBXCDR is managed by Jessica Taylor, the Founder and Executive Director of the OBXCDR, who is the client for this project. The center gathers data on bottlenose dolphin population size, movement patterns, diseases, and behavior in Roanoke Sound, NC. The OBXCDR catalog has a log of over 1,000 individually identified dolphins of the NNCESS, through both their dedicated and opportunistic photo- identification surveys.

2.2 Project Purpose The purpose of my project was to produce a status report for the OBXCDR on a vulnerable portion of the bottlenose dolphin population in Roanoke Sound, NC – females and calves. To accomplish this, I compiled information, such as interbirth intervals, lengths of calf dependency and group composition, for nursery groups and individual females to help inform the life history and ecology of this sex and age class of estuarine dolphins. To provide a comprehensive picture of female ranging patterns, I performed a home range analysis for groups and mature females with respect to reproductive state to determine if the presence of a dependent calf affected site fidelity. This spatial analysis can help provide insight into where to conservation efforts should be targeted and determine how environmental parameters affect habitat use patterns.

3. Methods 3.1 Data Collection and Preparation I compiled and analyzed data from dedicated surveys conducted by the Outer Banks Center for Dolphin Research from 2008-2019 in the Roanoke Sound, NC. Photo-identification is a mark-recapture method used to track individuals over time, based upon their distinctive features such as dorsal fin markings. During these surveys, the standardized survey route shown in Figure 4 was followed aboard a 17’ outboard vessel, under the NOAA General Authorization Permit LOC-21932, awarded to J. Taylor. Once dolphins were sighted, the boat left the transect line to begin a “sighting.” During the sighting, a designated photographer took photos of every 6 dorsal fin of the group using a Canon EOS 60D and standard photo-identification techniques. Data was recorded on the sighting sheet, which included: written location, GPS coordinates of group at the beginning of sighting and end of sighting, number of dolphins, neonates and calves, behavioral activities, weather conditions (i.e. cloud cover, visibility, precipitation) and water parameters (i.e. swell, Beaufort Sea State, temperature, salinity). Neonates were classified by their presence in echelon position, rostrum-first surfacing, fetal folds, and very small size. Older calves were classified separately, based on body size being about half or less of their associated mother. The sighting lasted until all dolphins in the group were photographed, the group was lost, the dolphins exhibited avoidance behaviors, or the sighting filled the hour time limit permitted under the permit. Once the sighting ended, the boat returned to the route until another group of dolphins was found or until the survey was finished. After completing the dedicated surveys, the FinBase database software was used to process the photo-ID images and sighting data sheets. Dorsal fin images from the dedicated surveys were sorted, graded for photographic quality, and matched to the OBXCDR catalog. Photos of dorsal fins were scored on focus, contrast, angle to camera, visibility of fin and distance from photographer. Only high-quality photos (scoring less than 12) were used in the analysis and matched. The matching process consisted of sorting photographs based upon each fin’s most distinguishing attributes, such as the locations and intensity of fin notches, scarring or shape. Level of fin distinctiveness was categorized as high, medium, low or not distinct. To reduce error in matching individuals, at least one other researcher checked each match to confirm. To determine spatial and compositional differences between nursery groups and non- nursery groups, I procured all dedicated survey sightings and associated data between 2008-2019 from FinBase. I then classified sightings into nursery groups or non-nursery groups, based upon whether at least one mother-calf pair was present. To complete the individual female analysis, I pulled survey data for six medium-highly distinct females: Lorna, Lisa Caroline, Wendy, Sinatra, Double Scoop and Fatlip. I only used data from the first sighting of a female on a given survey day. I then perused the raw photos and survey sheets to determine whether a dependent calf was present during each sighting. Only three out of the six females were available for spatial analysis due to data limitations, as at least four sighting points were needed to produce kernel density estimates. 7

3.2 Preliminary Analysis To compile information on nursery groups and individual females, I calculated overall average group sizes per sighting, and then for each year and season. I then compared nursery and non-nursery group sizes using a two-tailed t-test. I calculated interbirth intervals and the length of calf dependency for four females (Lorna, Sinatra, Wendy and Double Scoop) and then averaged these numbers to obtain representative values for the population. I chose these four 8 focal females because I had data on the full time period between the births of two successful calves. I determined length of calf dependency by subtracting the date of the final sighting of an associated calf with a mother from the date of first sighting of that calf as a neonate and converting the number of days to years. I calculated interbirth intervals by subtracting the date of the first sighting of a neonate associated with a female for longer than two years from the first sighting of the previous successful calf of the female.

3.3 Spatial Analysis To determine if there are any specific nursery areas within the study site, I used ArcPro to create kernel density estimates of home ranges based on reproductive state. For both groups and individuals, I created point data from the sightings, projected all data to the NAD 1983 UTM Zone 18N geographic coordinate system, and separated sightings based upon whether a dependent calf was present or not. I then used the Kernel Density tool to create unweighted kernel density estimates for each reproductive state, which created a smooth distribution around the points based upon their density over the area. From the kernel density outputs, I created home ranges from the 90% contour lines, which is the general range in which an animal travels while foraging, searching for mates or while caring for offspring (Burt, 1943). From the 50% contour intervals of the kernel density estimates, I created core areas, which are the areas of concentrated use. I then clipped the ranges with a land mask to eliminate land as a possible range for dolphins (Appendix Figure A1). To compare ranging patterns based on reproductive state, I intersected the core areas and home ranges to determine overlap of habitat use by females with calf in their without calf range. To further observe if there were differences between reproductive states or by environmental factors, I calculated size of the ranges, percent seagrass coverage and found the average depth and range of depth using Zonal Statistics (Appendix Figure A2). I also performed these spatial methods for groups with annual and seasonal temporal scales, to compare the stability of the core areas and home ranges. These results are included in Appendix Figures A3-A6.

4. Results 4.1 Group Results 4.1.1 Group Size Results

Of 238 group sightings from 2008-2019 in the Roanoke Sound, NC, 170 sightings were of nursery groups and 68 sightings were of non-nursery groups. Figure 5 shows the ratio of nursery groups to non-nursery groups in the Roanoke Sound, with a ratio of approximately five nursery groups to two non-nursery groups. No neonates were sighted in groups without at least one older calf present. The largest nursery group was seen on July 28th, 2019, with a total of 70 dolphins. Eighteen of the 70 dolphins were calves, and 10 of the 70 dolphins were neonates, so there were 28 mother-calf pairs in this group. The highest ratio of nursery to non-nursery groups during a single year was in 2019, as only 3 out of 40 sightings that year did not have a mother- calf pair. Forty-six nursery groups were sighted in spring (April – June), 109 sighted during summer (July – September), 14 sighted during fall (October – December) and only one sighted during winter (January - March). For non-nursery groups, 20 were sighted in the spring season, 34 sighted during summer, 14 sighted during fall and none sighted during winter.

On average, nursery groups were significantly larger than non-nursery groups (t = 7.33075, p < 0.00001), with 12.2 dolphins per sighting in nursery groups and only 3.94 dolphins per sighting in non-nursery groups (Figure 6). Summer had the largest average nursery group size of 13.12 dolphins, and fall had the largest average non-nursery group size of 4.29 dolphins (Figure 7). When average group size was broken out by year, there was a positive trend over time for both nursery and non-nursery groups, which suggests that group sizes have increased since 2008 (Figure 8).

4.1.2 Spatial Results

Generally, nursery group and non-nursery group core areas and home ranges were very similar in size, seagrass coverage, bathymetry, and location (Figure 9). The core area of nursery groups was 14.1 km2, and their home range was 44.9 km2. Seagrass covered 23% of the home 12 range, and the average depth in this range was 0.9 meters deep. The core area of non-nursery groups was 18.0 km2, and the home range was 37.3 km2. Non-nursery home range had 28% seagrass coverage with an average depth of 0.95 meters. Nursery groups utilized 57% of non- nursery core areas, and 88% of non-nursery home ranges.

4.2 Individual Female Results 4.2.1 Interbirth Intervals and Calf Dependency

The average interbirth interval for four focal females was 7.5 years, and the average length of calf dependency for these females was 4.8 years (Figure 10).

4.2.2 Spatial Results The average nursery core area size for the three females was 4.92 km2, and the average nursery home range was 20.09 km2. The average depth for nursery ranges was 0.94 meters, and the average seagrass coverage was 23%. For non-nursery core areas and home ranges, the average sizes were 1.3 km2 and 6.07 km2, respectively. Seagrass covered an average of 20% of the without calf home ranges, and the average depth was 0.89 meters. Core area overlap between reproductive states for all three females was zero, and the average home range overlap was 50%. 13

There were no significant differences between nursery and non-nursery core area size (t = - 2.4548, p = 0.0667) or home range size (t = -2.7847, p = 0.05419), seagrass coverage (t = - 0.2847, p = 0.4013), or mean depth (t = 0.3231, p = 0.3886).

Wendy was sighted six times with a dependent calf and four times without a calf during dedicated surveys in the Roanoke Sound from 2013-2019. Her core area and home range when observed with a calf was 1.94 km2 and 11.17 km2, respectively. Seagrass covered 15% of her 14 nursery range and the average depth was one meter. Wendy’s core area without a calf was 0.33 km2, and the area of her home range was 1.14 km2. The non-calf home range was covered 33% by seagrass, and the average depth in this range was 0.7 meters. Wendy’s did not use the non- calf core area when she was with a dependent calf, but she utilized 59% of her non-calf home range while she was with a dependent calf (Figure 11).

Lorna was sighted 16 times with calf and eight times without a calf in the Roanoke Sound from 2008-2019. Her core area with a calf was 3.88 km2, and the corresponding home range was 16.09 km2. Seagrass covered 35% of her calf home range, and the average depth was one meter. Lorna’s non-calf core area was 1.11 km2, and the area of non-calf home range was 8.08 km2. The range representing non-calf areas was covered 23% by seagrass, and the average depth in this range was also one meter. Lorna did not have any overlap of her core areas, and she only utilized 11% of her non-calf home range while with a dependent calf (Figure 12).

Lisa Caroline was sighted eight times with calf and five times without a calf from 2008-2019 in the Roanoke Sound. Lisa Caroline had a core area size of 8.95 km2, and her calf home range was 33.01 km2. Twenty percent of this range was covered by seagrass and the average depth in this area was 0.8 meters. Her non-calf core area was 2.45 km2, and the corresponding home range was 8.98 km2. Lisa Caroline’s non-calf home range was only 5% covered by seagrass, and the average depth in this range was 0.9 meters. She had roughly 0.3% of core area overlap, but she 79% of her non-calf home range while with a dependent calf (Figure 13).

5. Discussion 5.1 Nursery Groups I conclude that there is no specific “nursery area” within the Roanoke Sound that females use when they are accompanied by dependent calves. The high degree of overlap between core areas and home ranges signify that dolphin groups are utilizing most of the same areas, regardless of reproductive status. However, the entire Roanoke Sound could be considered a nursery habitat for these dolphins, judging from the high average nursery group size of 12.2 dolphins, and the ratio of nursery groups to non-nursery groups sighted during spring and summer. The relatively homogenous habitat of the Roanoke Sound, NC provides protection and abundant prey for these mothers, as well as other age-sex classes of this dolphin community.

5.2 Individual Females Estimates of interbirth intervals, 7.5 years, and periods of calf association, 4.8 years, were both relatively high. These long intervals are similar to those of female bottlenose dolphins from the Moray Firth, Scotland, whose average interbirth intervals were at least eight years (Grellier, 2000). This long period between births could signify the population is near carrying capacity, as the females are reproducing relatively slowly. Long periods of calf associations can point to increased rates of individual reproductive success, as female calves weaned later have a higher chance of living longer and reproducing themselves (Whitehead and Mann, 2000). Short interbirth intervals can be caused by density declines, which may be induced from natural or anthropogenic stressors (Thayer, 1984). All calves utilized in this analysis were born before the 2013-2015 Mid-Atlantic Unusual Mortality Event caused by the morbillivirus (Waring et al. 2018). Values of these parameters should be estimated again once enough data are available, to 17 determine if the UME caused a density-dependent response and shortened interbirth intervals in the population. Perhaps unsurprisingly, there was great individual variation in ranging patterns of the females analyzed, with home range overlap between reproductive states ranging from 11-79%. Each female utilized different areas and their ranging patterns sometimes varied with reproductive state. A study of mature females in Indian River Lagoon, FL also tested the concept of nursery areas based upon reproductive state and found similar results. The female dolphins of the Indian River Lagoon utilized the entire area with no regard to environmental parameters and had varied individual range overlaps (Gibson et al. 2013). These mothers are most likely adjusting their ranging patterns based on finding the best suited habitat at the time for either her calf’s protection or for satisfying her own energetic needs.

5.3 Management and Research Recommendations The entire Roanoke Sound should be considered an important nursery habitat for the NNCESS, and management and outreach efforts should focus on the entire area rather than a specific portion of the Sound. An example of a possible conservation measure is to improve water quality between the eastern side of Roanoke Island and Nags Head through promoting efficient stormwater management in local areas. Establishing voluntary speed reduction zones for boats in the southern section of Roanoke Sound between Duck Island and Rabbit Island would decrease the risk of boat strikes in the population. For outreach efforts, information on the local dolphin community and best practices should be included in rental boat agreements. ‘Dolphin- 101’ classes could be provided to local boaters and business owners and outreach programs could be developed and implemented at local schools and festivals to teach conservation practices. A specific example of public outreach to promote the conservation of these dolphins is a lesson plan I developed and implemented for eighth grade science classes showing how abiotic and biotic factors can affect habitat use. I created a Powerpoint presentation, a photo-ID fin- matching activity, a home range mapping activity and discussion questions. I won first place for this lesson plan at SciRen Coast in February 2020, an environmental education networking event in North Carolina. This lesson plan is included as an additional file on the Duke University Nicholas School of the Environment’s Master’s Project Database under this report.

5.4 Limitations and Future Research My study had a small sample size, especially of females without calves and non-nursery groups, so it is difficult to draw broad conclusions at the population level. Importantly, however, my study does suggest that the entire Roanoke Sound acts as a nursery area for females with dependent calves. A fuller analysis should be completed in a few years, once more data is available from the Outer Banks Center for Dolphin Research and other collaborating research institutions. To assist in improved documentation of mother-calf pairs, photo-identification surveys should note on the survey sheet when a distinct female and her calf are observed. To facilitate location of photographs of mother-calf pairs when uploading and matching pictures, a member of the survey crew should make a hand signal and the photographer should snap a picture of it immediately after capturing the mother-calf pair. In the database, an option should be created for female dolphins that allows a “with or without calf” field for each of her sightings. Known females and calves should be formally documented over time, to better determine lengths of calf dependency and interbirth intervals.

6. Acknowledgements I would like to sincerely thank Jess Taylor, the Executive Director for the Outer Banks Center for Dolphin Research, for being an amazing client for this project, a wonderful internship supervisor, and the best seventh grade science teacher. Thank you, Jess, for sparking my interest in ecology back in middle school and leading me down this path! I would also like to thank Dr. Andy Read for supporting me throughout this project and for his enthusiasm in regard to the coastal bottlenose dolphins of North Carolina. Thank you for letting me share the slides of FB717 from 1995 – us Generation Z kids have never seen those before! I extend my gratitude to the collaborators of the Mid-Atlantic Bottlenose Dolphin Catalogue for their willingness to share their survey efforts with me to complete FB717’s history. A big thank you to Kim Urian for facilitating the request for data and for the assistance in navigating the world of photo-ID catalogues. Thank you as well to Amy Engelhaupt (HDR Inc.), Rich Mallon-Day (Nags Head Dolphin Watch), Keith Rittmaster and Nan Bowles (North Carolina Maritime Museum) and Dr. Vicky Thayer (NC Division of Marine Fisheries). 19

7. Works Cited Burt, W.H. 1943. Territoriality and home range concept as applied to mammals. Journal of Mammalogy, Volume 24, pg. 346–352.

Gannon, D. P., and D. M. Waples. 2004. Diets of coastal bottlenose dolphins from the U.S. mid- Atlantic coast differ by habitat. Marine Mammal Science, Volume 20, pg. 527- 545.

Gibson, Q., and J. Mann. 2008. The size, composition and function of wild bottlenose dolphin (Tursiops sp.) mother–calf groups in Shark Bay, Australia. Animal Behavior, Volume 76, pg. 389–405.

Gibson, Q., Howells, E., Lambert, J., Mazzoi, M., and J. Richmond. 2013. The ranging patterns of female bottlenose dolphins with respect to reproductive status: Testing the concept of nursery areas. Journal of Experimental Marine Biology and Ecology, Volume 445, pg. 53-60.

Gorgone, A. M., T. Eguchi, B. L. Byrd, K. M. Altman and A. A. Hohn. 2014. Estimating the abundance of the Northern North Carolina Estuarine System Stock of common bottlenose dolphins (Tursiops truncatus). NOAA Tech. Memo. NMFS-SEFSC-664. 22 pp.

Grellier, K. 2000. Reproductive biology of bottlenose dolphins (Tursiops truncatus) using the Moray Firth, Scotland. Master's Dissertation, University of Aberdeen.

Hansen, L. J., L. H. Schwacke, G. B. Mitchum, A. A. Hohn, R. S. Wells, E. S. Zolman and P. A. Fair. 2004. Geographic variation in polychlorinated biphenyl and organochlorine pesticide concentrations in the blubber of bottlenose dolphins from the U.S. Atlantic coast. Science of the Total Environment, Volume 319, pg. 147–172.

Outer Banks Voice. 2018. “Dolphin rescued after tangling with crab pots in Roanoke Sound.” News article, web.

Read, A. J., Wells, R. S., Hohn, A. A., and M. D. Scott. 1993. Patterns of growth in wild bottlenose dolphins, Tursiops truncatus. Journal of Zoology, Volume 231, pg. 107 – 123.

Schwacke, L.H., E.O. Voit, L.J. Hansen, R.S. Wells, G.B. Mitchum, A.A. Hohn and P.A. Fair. 2002. Probabilistic risk assessment of reproductive effects of polychlorinated biphenyls on bottlenose dolphins (Tursiops truncatus) from the southeast United States coast. Environmental Toxicology and Chemistry, Volume 21, pg. 2752–2764.

Thayer, V. 2008. Life History Parameters and Social Associations of Female Bottlenose Dolphins (Tursiops Truncatus) Off North Carolina, USA. Dissertation, Duke University.

Waring, G. T., E. Josephson, K. Maze-Foley, and P. E. Rosel. 2018. "U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments – 2017." National Marine Fisheries Service.

Weir, J. S., N. M.T. Duprey, and B. Würsig. 2008. Dusky Dolphin (Lagenorhynchus Obscurus) Subgroup Distribution: Are Shallow Waters a Refuge for Nursery Groups? Canadian Journal of Zoology, Volume 86, pg. 1225–34.

Whitehead, H. and J. Mann. 2000. Female reproductive strategies of cetaceans: life histories and calf care. Cetacean Societies: Field Studies of Dolphins and Whales. The University of Chicago Press, Chicago, pg. 219–246.

Würsig, B. and M. Würsig. 1977. The photographic determination of group size, composition and stability of coastal porpoises, Tursiops truncatus. Science, Volume 198, pg. 755-756.

16 USC CHAPTER 31-Marine Mammal Protection Act of 1972 as Amended. Marine Mammal Commission. Amended 2007.

8. Appendix

Figure A1. Spatial Analysis ArcPro Model Example

Figure A2. Spatial Analysis Reference Data

Data Source Application

Marine Mammal 2016 NC ESI NOAA Office of Response Used to create land mask to clip ranges through Habitat Shapefile and Restoration Raster Reclassify Seagrass Polygon Intersected with ranges to find seagrass coverage North Carolina One Map Geospatial Portal Shapefile percentages Bathymetric Point NOAA Raster Navigational Chart, NOAA Interpolated using Inverse Distance Weighted to Data Office of Coast Survey website use in Zonal Stats of ranges Seasonal OBXCDR dedicated surveys surface water Interpolated using Inverse Distance Weighted to Temperature and testing use in Zonal Stats of ranges Salinity Point Data

Figure A3. Maps of Annual Group Spatial Results

Figure A4. Chart of Annual Group Spatial Results

Home Home Group Sample Core Area Core Area Seagrass Average Year Range Size Range Type Size (n) Size (km2) Overlap Coverage Depth (m) (km2) Overlap Nursery 8 0.93 2.21 0.04% 1.025 2008 17% 18% Non 4 2.01 9.24 14% 1.01 Nursery 9 9.37 58.60 21% 1.224 2009 45% 64% Non 7 4.46 17.21 35% 0.654 Nursery 13 3.14 11.36 24% 0.776 2010 0% 30% Non 2 0.85 6.17 23% 0.839 Nursery 18 6.46 29.01 39% 0.867 2011 0% 57% Non 7 2.34 9.70 26% 1.115 Nursery 22 11.21 42.23 28% 0.905 2012 80% 76% Non 11 7.15 23.57 48% 0.867 Nursery 11 3.47 15.97 27% 0.999 2013 25% 38% Non 4 3.43 12.43 27% 1.27 Nursery 8 15.25 44.54 22% 1.09 2014 25% 94% Non 11 2.19 12.53 47% 0.811 Nursery 11 6.93 18.93 17% 0.906 2015 43% 49% Non 2 0.85 1.51 0% 0.966 Nursery 10 0.49 11.15 16% 0.914 2016 0% 52% Non 7 1.35 4.16 54% 0.538 Nursery 9 4.35 13.40 20% 0.847 2017 88% 100% Non 2 0.37 0.69 27% 0.690 Nursery 14 4.46 31.80 32% 0.848 2018 80% 92% Non 8 3.80 17.12 46% 0.825 Nursery 37 6.69 19.79 37% 0.847 2019 25% 55% Non 3 2.78 8.99 24% 0.960

Figure A5. Map of Seasonal Group Spatial Results

Figure A6. Chart of Seasonal Group Spatial Results

Core Home Core Home Average Average Average Group Sample Area Range Seagrass Season Area Range Depth Temp. Salinity Type Size (n) Size Size Coverage Overlap Overlap (m) (F) (ppt) (km2) (km2) Spring Nursery 46 18.65 32.39 31% 0.958 79.60 13.06 87% 61% (April – June) Non 20 9.32 44.14 22% 0.915 79.73 13.85 Summer Nursery 109 9.57 41.88 24% 0.913 82.19 17.02 (July – 48% 80% 81.88 16.62 September) Non 34 12.31 34.82 30% 0.933 Fall Nursery 14 2.12 10.11 13% 0.836 70.76 17.37 14% 25% (October – 69.80 20.21 December) Non 14 3.17 14.45 31% 0.828