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Item Social interactions in New Zealand common bottlenose dolphins (Tursiops truncatus) : association dynamics, skin diseases and aggressive injuries, and variations in vocal signals : a thesis presented in partial fulfilment of the requirement for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Auckland Campus, New Zealand(Massey University, 2022) Patin̋o-Pérez, JessicaSocial behaviour is described as a series of interactions between two or more members of the same or different species that usually benefits all the individuals involved. Individuals form strong bonds because of these interactions, which might be cooperative, hostile, mutualistic, or altruistic. Depending on the nature of the relationships and participants, social behaviour can lead to the establishment of distinct social systems. Although it is evident that social behaviour does not have to be selfless, the question of why and how social behaviours occur in animals is still being debated. According to Krause and Ruxton (2002), sociality emerges when the advantages of long-term social contacts outweigh the drawbacks of such close relationships with conspecifics. Among the advantages of living in a group are increased opportunity for food and mating, as well as protection from predators. This sociality, on the other hand, might have negative implications, such as increased rivalry for mates and resources or increased disease transmission risks. I investigated multiple aspects of the social lives of common bottlenose dolphins Tursiops truncatus (hereafter bottlenose dolphins) in New Zealand. Historically, the north-eastern North Island bottlenose dolphin population has been intensively studied at the Bay of Islands since it was the only place where dolphins are constantly sighted. A rapid decline in this population and high calf mortality raised concern about the viability of this population. The key objective of my research was to understand how different social aspects influence the population of bottlenose dolphins at Great Barrier Island (GBI), New Zealand, an area that was recently describe as a ‘social hub’ for the species. Although, throughout my thesis I talk about the population of dolphins present in GBI, it is important to keep in mind that this is one part of the entire North Island population. In the first part of my thesis, I describe the social structure of bottlenose dolphins in GBI using historical data from the Bay of Islands (BOI) and GBI, in addition to my own data. I analysed their social structure by examining: (1) preferred/avoided companions, (2) strength and distribution of associations, (3) temporal and spatial patterning of associations, and (4) residence times. The analysis of BOI-GBI showed two distinct social communities, each of which is made up primarily of members photographed only in their respective areas. Only a few individuals were identified in both areas. For GBI, two datasets were analysed: 2011-2013 and 20015-2019. During both time periods, the population exhibited low levels of association, characteristic of fission-fusion societies like bottlenose dolphins, but the populations also showed some structure, with dolphins forming long-lasting bonds with some individual and avoiding others. Moreover, during 2015-2019, two social communities were identified in the population, exhibiting different ranging patterns and pattern of association within communities. The temporal analysis showed that during 2011-2013, the population exhibited a combination of stable associations among individuals and other individuals that associate, disassociate, and may reassociate again over extended periods of time. During 2015-2019, dolphins associate for short periods of times before breaking up, happening at two different times. Analysis of residency times during 2011-2013, showed that the models including emigration + reimmigration were the best to describe the population, while during 2015-2019, were the models including emigration/mortality. Bottlenose dolphins associate in groups that frequently change in size and composition, characteristic of fission-fusion societies. Skin lesions and tooth rakes can be used to assess natural and anthropogenic pressures within a population, which is useful information for better understanding population dynamics. In addition, tooth rake marks are a measure of the level of social contacts within a population and are usually the outcome of inter- and intra-specific interactions. Gregariousness is a major component in disease transmission and increases the likelihood of aggressive confrontations. When it comes to diseases, animals with a high incidence of interactions with others will increase the chances to spread diseases, putting their populations at risk. In this thesis, I described for the first time the prevalence of skin lesions and tooth rakes for the north-eastern population of bottlenose dolphins. In addition, I described the skin lesions found in, and determined the location of, the skin lesions and tooth rakes on dolphins’ bodies. I also proposed a protocol to assess skin lesions and what are the implications for future studies. Finally, I tested if there was an association between skin lesions and tooth rakes, and the strength of the dolphins in their social network. I wanted to know if presence or absence of tooth rakes was defined by the strength in their social network and if dolphins with a higher coverage score of tooth rakes will have a higher strength in their social network. In addition, I examined if tooth rake scores were different based on the presence and absence of skin lesions. From the literature, I found 19 skin lesions with distinct and non-overlapping definitions. These lesions were the foundation of the protocol that I used to assess lesion presence in my population. Eight skin lesions were present in bottlenose dolphins at Great Barrier Island, with different prevalence in the population and varying distribution across different parts of the dolphin body. Pale lesions had the highest prevalence at 84.4% and were found across four body parts, but mainly in the dorsal fin. Similarly, black lesions, white-fringe spots, nodules, and dark-fringe spot were found in four body parts but their prevalence in the population were lower (33.1%, 17.5%, 11.7%, and 15.6%, respectively). Finally, spotted lesions (10.4%), white fin fringe (5.84%), and tattoo-like disease (4.54%) had the lowest prevalence and were found in three, two, and one body region(s), respectively. Tooth rakes also had a high prevalence in the population (94%), and they were found mostly on the dorsal fin (100%, n = 150), followed by mid-flank (90.2%, n = 139), and anterior section (88.3%, n = 136). The mean coverage score did not change significantly over time (images were compared up to 20 months apart). From the 150 dolphins included in the tooth rake analysis, individuals sighted four or more times were included in the analysis of tooth rakes and strength of associations, giving a sample size of 50 dolphins. I found that the strength of the individual (i.e., it is the individual’s gregariousness) in the social network does not affect the tooth rakes an individual has and having tooth rakes is not dependent on strength. In addition, coverage score (a value obtained dividing the presence of skin lesions in 12 body parts by their visibility) did not change with the presence of skin lesions. In this chapter, I emphasised the need to determine the overall health of cetaceans in the North Island, as well as the need for more precise and systematic evaluations of the skin lesions of this population and other cetaceans in the region. Cetaceans are highly vocals animal that depend on sound to communicate, navigate, and find food. Most dolphins can produce three different types of sound, from which whistles have been the most studied due to this type of vocalisation being within the human hearing range and more easily visualised in spectrograms for analysis. Whistles are narrowband, frequency modulated sounds with strong harmonic structure and are used in social interactions. Geographic variation in whistle characteristics has been reported in many populations of bottlenose dolphins around the world and the causes of this variation are diverse. For the first time in New Zealand, I have compared the variation in whistle characteristics of two isolated populations of bottlenose dolphins, GBI and Fiordland, using seven time-frequency variables. In addition, I compared the parameters between these isolated populations using Random Forests analysis (RF) and assessed the influence of location, group size, and presence of immatures on these characteristics. Finally, I compared the whistle characteristics of bottlenose dolphin populations from around the world with New Zealand populations using a hierarchical cluster analysis. Whistle characteristics of both populations were similar to other populations around the world, surprisingly, my populations were similar to other populations from the northern rather than the southern hemisphere regions. A comparison of whistle parameters between GBI and Fiordland, showed that the Fiordland population had longer whistles and more inflection points than whistles from the GBI population. Whistles from these two populations were distinct enough to be correctly allocated to one population based on acoustic measures alone with a 90% of accuracy. The most important variables for classification were whistle type contour, duration, and end frequency. I obtained two principal components from the NIPALS PCA. The first principal component (PC1) explained 55.6% and the second component (PC2) explained 44.4% of the variance. Linear Mixed Models on PC1 and PC2 were used to assess whether whistles acoustic parameters were influenced by location, group size, and presence of immatures. I found that PC1 was not different between areas or with the presence of immatures. However, minimum frequency and duration differed between the two populations (location). Overall, my research has produced significant new knowledge on the social structure, prevalence of skin lesions and tooth rakes, and geographic variation in vocalisations of bottlenose dolphins. My research provides better understanding of the high degree of social and acoustic plasticity of bottlenose dolphins by applying state-of-the-art approaches such as social network and random forests analyses to multiple temporally and spatially diverse datasets. In addition, I developed a useful tool for non-invasive categorisation of infectious skin diseases that can be used by researchers and conservation practitioners worldwide to assess the health of individuals and populations.Item The ecology of bottlenose dolphins (Tursiops truncatus) in the Hauraki Gulf, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, New Zealand(Massey University, 2018) Outhwaite, Blair R.Bottlenose dolphins (Tursiops truncatus) are one of the most studied cetacean species in the world. In New Zealand, this species is classified as Nationally Endangered and studies are generally limited to just a few known core areas. Herein, I examine the use of social media in citizen science as a means of collecting occurrence data of bottlenose dolphins in the inner Hauraki Gulf. A dedicated research vessel was employed to verify data collected by citizen scientists. This study also investigated the habitat selection of bottlenose dolphins at Great Barrier Island, an area only recently described for its importance to the north-eastern North Island population. Data collected for a behavioural budget and whistle repertoire were recorded on a dedicated research vessel with the aim of understanding habitat selection. Environmental variables were used to model behavioural states in order to determine how habitats were utilised by the dolphins. The whistle repertoire was assessed to understand how it correlated with behavioural states and group dynamics. A total of 260 sightings of bottlenose dolphins were reported by citizen scientists between April 2015 and July 2016. Only 42 of these were independent reports. Of the total number of reports, 73.5% did not identify a dolphin species. Citizen scientists identified three species of cetacean. Killer whales (Orcinus orca) were often reported correctly, however all five reports of common dolphins (Delphinus delphis) were misidentified, and 33.3% (n=5) of the reports identifying bottlenose dolphin were either unconfirmed or misclassified. Researchers’ verifying the identity of the species reported was the most useful method of confirming citizen science reports in this study (34.8%). Citizen scientists failed to detect dolphins on only three occasions that the research vessel or platform of opportunity did. Yet, citizen scientists were able to detect bottlenose dolphins more often than either the research vessel or platform of opportunity. The number of independent citizen science reports, research vessel encounters and platform of opportunity encounters for bottlenose dolphins were similar over each austral season. Notably, only the platform of opportunity had encounters over summer, both of which were in deeper water, outside of the study area. Bottlenose dolphin group size was often underestimated by citizen scientists in this study, though rigid comparisons were not possible for group size or behavioural state due to small sample sizes. The proportion of total reports varied temporally between seasons, and was highest in the mornings for autumn and winter, but peaked during the afternoons in spring. Bottlenose dolphins did not appear to use the study area frequently and were usually recorded travelling. The majority of behavioural observations at Great Barrier Island were made during winter and spring. Bottlenose dolphins were recorded between 13.5 and 24.1°C and in depths of 1.8 to 55.3m. The largest group sizes were recorded in autumn while the smallest group sizes were recorded most often in spring and summer. While the largest group sizes were recorded in the warmest sea surface temperatures and greatest depths, there was no significant difference between group size categories. Resting made up the largest proportion of the behavioural budget (32.1%), while foraging (8.2%) and socialising (9%) were rarely recorded. The models predicted that the behavioural budgets at Great Barrier Island were determined primarily by abiotic factors (e.g. depths and sea surface temperature). The mean whistle rate, calculated as the number of whistles per minute per dolphin, recorded at Great Barrier Island for bottlenose dolphins was 0.50 (SD=0.53) and the highest whistle rate was recording during foraging (1.17, SD=0.98). There was no significant difference in whistle rates between group size categories. Whistles recorded lasted on average 0.84s (SD=0.52), with a mean frequency of 11.6kHz (SD=2.34). The parameters with the highest variation were the number of inflection points, length, and frequency range of whistles. The Ascending whistle type was the most commonly recorded, and particular whistle types were correlated to behavioural state and group size category. This study represents the first instance that citizen science utilised social media in the Hauraki Gulf and suggests there is potential for continued monitoring of bottlenose dolphins with citizen science, if recommendations are applied. It also presents the first behavioural budget and whistle repertoire for bottlenose dolphins at Great Barrier Island. This study reported a unique behavioural budget and acoustic parameters that imply its importance for the north-eastern North Island population. Continued monitoring of this population is recommended to ensure this population is managed appropriately.Item Context-specific signal plasticity of two common bottlenose dolphin ecotypes (Tursiops truncatus) in Far North waters, New Zealand : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Albany, New Zealand(Massey University, 2018) Peters, Catherine H.Common bottlenose dolphin (Tursiops truncatus, referred to hereafter as bottlenose dolphin) fission-fusion groupings are temporary in nature, lasting from minutes to hours, necessitating efficient signal exchange. The selective pressures and contexts acting on signal exchange, such as ecotype variation, are not well understood. The objectives of the current study are three-fold to: 1) quantify the density, distribution and abundance of bottlenose dolphin ecotypes and identify the nature and areas of spatial overlap between the two in Far North waters; 2) examine aspects of mechanical signal exchange based on biotic and abiotic factors; and 3) estimate the effect of key ecotype specific contexts on group multimodal signal exchange. This thesis applies a holistic approach to the assessment of signal exchange in ecotypes using the highly social bottlenose dolphin as a model genus. Additionally, this body of work provides the first comprehensive assessment of oceanic bottlenose dolphin distribution, abundance, and behaviour ecology and the first ecotype spatial and behavioural overlap within New Zealand waters. Knowledge of population size, social behaviour, threats, and ability to integrate new individuals is required to define management units. Although it has long been recognised that the nationally endangered coastal bottlenose dolphin is not resident in the Bay of Islands but genetically part of a North East coast population, no studies have quantified bottlenose dolphin distribution in Far North waters outside of the Bay of Islands. This study provides the first systematic analysis of detectability, distribution, and spatial overlap of both the coastal bottlenose dolphin and the previously unquantified oceanic bottlenose dolphin in Far North waters. Results suggest Far North waters are important for the coastal bottlenose dolphin, supported by a higher average density (0.620 individuals/kilometre) than that reported for the coastal bottlenose dolphin in other areas of the North East coast population. The importance of assessment outside areas of commercial interest is further reinforced in this study. The Bay of Islands local abundance is not reflective of the coastal bottlenose dolphin in the wider area, as indicated by the higher Far North waters estimates of 212.8% (Austral Summer) and 196.1% (Austral Winter). With no previous density or abundance estimates for oceanic bottlenose dolphin in New Zealand, no comparisons can be drawn with other studies or historic research. However, the distance sampling-based population estimate of 3,634 (SE = 152) indicates oceanic bottlenose dolphin abundance is much higher than the 389 (SE = 108) coastal bottlenose dolphin abundance estimate in Far North waters, even though their distribution is seasonal with detection only in austral Summer and Autumn. Kernel density also indicates the representative ranges (95 % kernel range) of the coastal bottlenose dolphin are smaller than the oceanic bottlenose dolphin, extending over a total area of ~794 km2 and ~1,003 km2, respectively. This study further suggests these ecotypes should be described as largely parapatric and non-resident in nature, with a minimal spatial overlap of only 7.4 % of Far North waters surveyed (~196 km2). This is further supported by no sightings of the two ecotypes within the same survey zone on the same day (n = 372 bottlenose dolphin sightings) during the present study. Behaviour can further add insight into the partitioning and variation of parapatric units within a species. In Far North waters, whilst research on surface behaviour has been previously conducted in the Bay of Islands, behavioural assessment in wider areas and based on a holistic assessment of multiple signal forms is lacking in the literature. This study, however, applies a systematic sampling technique and integrated analysis to identify trends in signal exchange use. This is done by examining multiple behavioural modes (states and events, surface and subsurface) concurrently. This ultimately provides an additional method for quantifying group behavioural plasticity as a result of covariates acting on parapatrically occurring bottlenose dolphin groups. In one assessment, cues were taken from avian acoustic research to accurately quantify and analyse ecotype variation in call repertoire. In support of the parapatric definition, call repertoire was correctly assigned to ecotype, with an 89.4% success rate (n = 31,432 calls). Of all parameters examined, 71.4% exhibited significant variation, with harmonics and contour inflections used significantly more in oceanic bottlenose dolphin. Both Dynamic Time Warping in Luscinia and Hidden Markov Models add reliable insight into the categorisation of key signal parameters and important tools for the primary assessment of differences in bottlenose dolphin behaviour within Far North waters. Including the full behavioural repertoire of oceanic bottlenose dolphin and coastal bottlenose dolphin through Hidden Markov Models adds additional insight to the possible drivers behind the divergence in the call parameters noted. It is notable that signal parameters are not influenced by the same key drivers for both ecotypes. This is an important finding in a species in which most communication exchanges involve acoustic signals in some form. The formation of interspecific groupings has the largest effect on social signal exchange in oceanic bottlenose dolphin of all covariates considered. The response magnitude is associated with group parameters, for example, the ratio of individuals (e.g. pilot whales (Globicephala sp.) to oceanic bottlenose dolphins) and the behaviour and/or overall size of the focal group. These aspects in turn determine the effect of participation in interspecific groups on oceanic bottlenose dolphin behaviour. Oceanic bottlenose dolphins in interspecific groups with pilot whales display higher call plasticity, both in the time and frequency domain, utilising significantly higher measures for 66.7% of parameters, including longer and more complex calls (increased number of harmonics and inflects), than in intraspecific oceanic bottlenose dolphin groups. Signal adaptation is more evident when oceanic bottlenose dolphins and pilot whales are directly interacting with each other during social events. During socialising states, the predominant subsurface event type observed is aggression (59.4%, n = 233). As the ratio of pilot whales to oceanic bottlenose dolphins increases, the use of long-distance signal exchange decreases. This suggests that the observed decreases in interspecific similarity of whistle parameters during social interactions may act to increase the ability to differentiate species-specific rather than whole group signal exchange cues. Although species-specific call differentiation is likely heightened by variation in gross morphology, phylogeny and geographical constraints, frequency domain characteristic overlap between oceanic bottlenose dolphins and pilot whales. The detected adjustments in signal structure away from intermediate values may suggest a decrease in the increment in this overlap. Support is given to the theory that signal exchange might be modified not only as a result of group behaviour state but also due to the signaller’s motivational state (i.e. stress). While the full biological effects of changes in whistle rates and parameters remain uncertain, these changes add initial insights to the dynamics of interspecific groupings. Number of vessels had largest effects on coastal bottlenose dolphin social signal exchange, with response magnitude significantly related to group composition (ex. with or without calves) and use of other signal exchange behaviours (ex. tactile type and rate). The response is also influenced by acoustic parameters considered (frequency or call rate). The highest coastal bottlenose dolphin density area, the Bay of Islands, contains the highest proportion of groups with calves and the highest level of vessel traffic in Far North waters. Groups with calves favour sounds typically used for short-distance signal exchange, appearing to increase the use of mechano-reception in the presence of vessels. Overall, coastal bottlenose dolphins are more likely to: (1) leave the low-call-rate state in the presence of one to two vessels (within 300m); (2) leave the high-call-rate state when three or more vessels (adults only), or two or more vessels in the case of groups with calves, are within 300m; and (3) stay in a relatively silent state when more than three vessels are present. Furthermore, coastal bottlenose dolphins are more likely to (1) leave the low-call-rate state when contact rate is low; (2) leave the high-callrate state when contact rate is high; and (3) stay in a relatively silent state when contact rate is high. This suggests an inverse relationship exists between call rate and contact rate, i.e. as possible vessel effect increases, vocalisation-mediated coordination decreases, and mechanomediated coordination increases with a lower threshold for groups with calves than groups without. Several drivers of elevated signal exchange rates have been suggested in the presence of vessels. These include an increased motivation for individuals to stay close together, a changed group cohesion and amplified arousal. However, this study adds new insights with the quantification of multi-modal signal exchange in the presence of vessel. This has not been the focus of previous research in any of the bottlenose dolphin populations in New Zealand. Distribution, density, and abundance is now available for both bottlenose dolphin ecotypes, with multimodal group behaviour in ecotype specific contexts additionally quantified. As such, supplementary monitoring and reviews of the coastal bottlenose dolphin and oceanic bottlenose dolphin parapatric populations in New Zealand are essential. Pre-emptive rather than reactive conservation is recommended to effectively manage both bottlenose dolphin ecotypes separately and efficiently in New Zealand waters.Item Spatial ecology of delphinids in Queen Charlotte Sound, New Zealand : Implications for conservation management : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Marine Ecology Massey University, Albany, New Zealand(Massey University, 2019) Cross, Cheryl LynneUnderstanding species’ ecological interactions and area usage depends on clear insight into their temporal and spatial patterns. Such information combined with recognition of regional human-invested interests, is crucial for developing conservation management efforts. Queen Charlotte Sound (QCS), South Island, New Zealand is a unique environment inhabited by diverse marine life, including several cetacean species. The area is subject to rising levels of anthropogenic activity inclusive of marine farming, tourism and vessel traffic. With conservation management in mind, this thesis focused on three key delphinid species: Hector’s (Cephalorhynchus hectori), bottlenose (Tursiops truncatus) and dusky dolphins (Lagenorhynchus obscurus). Specifically, this study sought to: 1) explore long-term historical temporal and spatial trends in delphinid occurrence 2) identify recent patterns in delphinid distribution, density and range 3) investigate delphinid species’ habitat use 4) initiate research of regional swim-with-dolphin tourism. Dolphin sighting data were: 1) collated from tour vessel logbooks spanning 1995–2011 and 2) collected during dedicated surveys aboard opportunistic platforms from 2011–2014. Dynamic and static environmental variables were sourced from local government agency databases to use in analyses with both datasets. Historical delphinid presence (from logbook data) was correlated with dynamic environmental variables during two separate time frames (1995–2002; 2003–2011), using Generalized Additive Models (GAMs) and Generalized Linear Models (GLMs). Spatial patterns of these sightings were explored across temporal periods (i.e., seasons; blocks of year). Dedicated survey data were used to generate kernel density estimates and to determine species’ range and central range. These dolphin density estimates were correlated with static and dynamic habitat parameters using (GAMs). Spatial predictions were then generated from the resultant significant variables. Bottlenose dolphin engagement in swim-with-dolphin encounters was assessed according to several proxies using Linear Models (LMs) and GLMs. A total of 5,295 historical records consisting of 6,055 delphinid sightings were compiled, demonstrating a long-term presence of the focal species. Of these, Hector’s dolphins consistently had the highest trip encounter rate. Seasonal patterns indicated peaks in occurrence for Hector’s during summer/autumn, bottlenose during autumn/winter and dusky dolphins during winter/spring. Further investigation with GAMs suggested that each species’ presence was associated with a unique set or range of dynamic variables. Annual variation occurred amongst all species. During both historical time frames (1995–2002 and 2003–2011), Hector’s dolphin occurrence was associated with higher SST values. Bottlenose dolphins displayed an association with mid-low SST (during 1995–2002) and with high turbidity (during 2003–2011). Dusky dolphins were influenced by low SST (during both time frames) and from 2003–2011 were also influenced by low turbidity and mid-value tidal range. Spatial patterns illustrated that Hector’s and dusky dolphins have become more restricted in their use of QCS over time. Finally, logbook data indicated an increased prevalence of swim-with-dolphin encounters, suggesting an expansion of local tourism from 2004–2011. A total of 677 dedicated opportunistic surveys were completed. These equalled 1,613 hrs of search effort spanning 263 km2. Sighting rate calculations indicated that Hector’s and bottlenose dolphins occurred more frequently than dusky dolphins. Seasonality was particularly notable amongst Hector’s dolphins, whereas the sighting and encounter rates were higher during summer and autumn. The collective range of all species suggests that delphinids utilized most of QCS. However, both the range and central range of Hector’s dolphins were more limited. Notable spatial patterns included peaks in Hector’s dolphin density mid-Sound, during summer/autumn and peaks in bottlenose dolphin density toward the outer Sound during summer/autumn. Temporal overlap was relatively high for bottlenose and Hector’s dolphins (0.67) and low for Hector’s and dusky dolphins (0.22), while spatial overlap was quite low for all species combinations. The patterns explored here offer evidence of temporal and spatial multi-species habitat partitioning within QCS. This may be due to the broader ecological trends within New Zealand and is likely attributed to the availability and movement of prey. Habitat models (GAMs) indicated a unique set of significant drivers associated with dolphin density for each species. Hector’s dolphins displayed an association with dynamic and static variables (SST, fluorescence, depth, slope and distance to the closest marine farm). Dusky dolphins were influenced by the same variables, as well as year. Consistency with the earlier models in the association with SST for Hector’s (higher values) and dusky dolphins (lower values) was detected. Bottlenose dolphins were only influenced by static variables (depth, slope and distance to the closest marine farm) and year. The habitat differences suggested by these models offer further insight to the ecological meaning of dolphin spatial patterns in QCS. In particular, these findings offer additional evidence of delphinid resource partitioning, specifically on a trophic scale. This likely occurred because all three species exhibit both dietary and foraging plasticity. While similarities were observed between comparable studies in other areas, the presence of some variation is likely due to unique physical and hydrographic regional characteristics. Spatial predictions that were generated from significant model variables were valuable in estimating potential locations of dolphin density beyond sighting locations, including areas that they previously occupied. Data representing animal area usage, like those presented here, are integral to conservation management, especially amidst growing anthropogenic influences, like tourism. This first ever tourism-based study in QCS indicated bottlenose dolphins as the main target species for swim-with-dolphin activity. A total of 190 bottlenose dolphin swim encounters were assessed according to several proxies. Interactions were very short (𝑥̅=4.2 min), with most dolphin reactions neutral (82.9 %), suggesting animal disinterest. Swim encounters occurred regularly, irrespective of group composition or behavioural state. Furthermore, tour operators travelled great distances (𝑥̅=11.7 km) amongst dolphin groups to complete swim encounters, demonstrating pursuit of interaction. Collectively, these proxies suggest a lack of dolphin engagement in swim activity. This thesis encompassed the first multi-species comprehensive assessment of delphinid density, range, habitat use and swim-with-dolphin tourism in QCS. It established a baseline of data, contributing to regional ecological knowledge. Detailed evidence of when and where three sympatric dolphin species utilized QCS was provided. Moreover, this work established an understanding of delphinid inter-specific interactions and associations with habitat variables. Applications of the findings presented here include contributions to developing comprehensive conservation management and further research. Periods and regions of high density and predicted density may be considered in regional management decisions regarding anthropogenic use of the Sound and during the design of future surveys.Item Abundance and behavioural ecology of bottlenose dolphins (Tursiops truncatus) in the Marlborough Sounds, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University(Massey University, 2007) Merriman, Monika GayleIn order to survive, animals require both food and protection from predators. These ecological factors are major determinants in habitat selection and social interactions. Determining the causes of habitat selection and examining the behavioural ecology of marine mammals is often a difficult task. In the ever-changing marine environment, factors such as shifts in prey availability, turbidity, sea surface temperature, and salinity result in a highly dynamic ecosystem that influences distribution. This research's primary focus was to establish baseline information on the behavioural ecology of bottlenose dolphins, Tursiops truncatus in and around the Marlborough Sounds, New Zealand. Boat based surveys, photo-identification, and group focal follows were used to assess spatial distribution, abundance, home range, and social interactions. Boat based surveys were conducted from 2003 to 2005. Photo-identification data collected from 1997 to 2005 were used in analysis. Uniquely marked individuals (n = 335) were sighted throughout the Marlborough Sounds and long-term site fidelity was observed among members in this large open population. Aggregations of between 3 to 172 individuals were observed with a median group size of 12. Group size was influenced by the presence of calves, with groups tending to be larger when calves were present. Larger groups were found to rest more than smaller groups and resting occurred less in the spring months. Association patterns revealed long- and short-term preferred associations between individuals throughout the Sounds. Distribution and movement patterns of dolphins showed they used all areas within the Marlborough Sounds. The population of bottlenose dolphins observed in the Marlborough Sounds were found to be semi-resident with 211.5 (C.I. = 195 - 232) individuals utilising the Sounds year round while other individuals were found to migrate in and out of the area on an annual basis. The Marlborough Sounds appear to be only a portion of a much larger home range for this population.Item Spatial ecology and conservation of cetaceans using the Hauraki Gulf, New Zealand : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Marine Ecology at Massey University, Albany, New Zealand(Massey University, 2014) Dwyer, Sarah L.Understanding species’ distributions and habitat use, and how they change spatially and temporally, is crucial for conservation management. The Hauraki Gulf, North Island, New Zealand is a highly productive marine ecosystem that is important for a range of marine megafauna, including cetaceans. This study investigated the spatial and temporal distribution and habitat use of three focal species: common dolphin (Delphinus sp.), Bryde’s whale (Balaenoptera edeni) and bottlenose dolphin (Tursiops truncatus) in the Hauraki Gulf, with the overarching goal of providing scientific information for conservation and management. A dedicated research vessel was used for data collection and surveys were focused in the inner Hauraki Gulf (IHG) and off the west coast of Great Barrier Island (GBI; outer Hauraki Gulf). The likely spatial use of the Hauraki Gulf by cetaceans, and how that likelihood changes seasonally, was investigated using species distribution modelling (SDM). A novel approach to SDM for cetaceans that incorporates detection probability was investigated with occupancy models and compared with generalised linear model (GLM) outputs. Additionally, photo-identification was used to assess the population ecology of bottlenose dolphins using GBI waters for the first time in light of the reported decline in abundance in what has formerly been recognised as the core region (i.e. Bay of Islands) for the North Island population. Survey effort totalled 20,803 km in IHG and GBI waters during 279 survey days between January 2010 and November 2012. Central northern IHG regions were important for common dolphins year-round, with increased probabilities of encounter during winter and spring compared with summer and autumn at GBI. The inshore movement of common dolphins in Hauraki Gulf waters during winter may represent an overall offshore to inshore shift in distribution, combined with an influx of dolphins into the Gulf from the wider surrounding areas of the northeast coast. This is likely to be related to prey distribution. Estimates of the functional habitat models suggested that the use of more southerly waters in the IHG during summer and autumn reflects habitat use by nursery rather than by feeding dolphin groups. However, the overall predictive maps were more temporally and spatially similar to the feeding than the nursery group predictions, indicating that prey availability likely has important implications for the general distribution and habitat use patterns of common dolphins in the Hauraki Gulf. Furthermore, occupancy model outputs showed similar spatial and temporal trends in distribution and habitat use of common dolphins in the IHG as the GLMs. While incorporating detection probability reduced the bias in parameter estimates, the depth covariate was still identified as the most important predictor of seasonal occurrence using both model types. Overall, the spatial and temporal distribution patterns of Bryde’s whales were the most unpredictable of the focal species, particularly inter-annually off GBI. Notably, habitat use by Bryde’s whales and common dolphins in GBI waters was considerably different, unlike in IHG waters. This may be indicative of whales foraging more frequently on krill in outer Hauraki Gulf waters than in the IHG, albeit dependent on inter-annual variation in prey availability. It is important to note that the results of this study occurred under predominantly La Niña conditions. Given the strong effects of winds on ocean circulation in the Hauraki Gulf, variations in patterns described here may vary under more neutral and El Niño conditions. The high encounter rates of bottlenose dolphins at GBI compared with the IHG support the hypothesis that GBI is a hotspot for the North Island population. Groups using GBI waters were larger than previously reported for the North Island population and predominantly contained neonates and calves. In particular, the southwest coast of GBI appeared important for bottlenose dolphins, possibly due to a combination of factors including food availability, its suitability for breeding or calving, and the likely decreased levels of anthropogenic pressures associated with other regions of the population’s home range. Photo-identification analyses confirmed overall site fidelity (MSR = 0.33) to the GBI region was high, albeit with variable re-sighting patterns among individuals. A total of 171 dolphins (CI = 162–180) used the area during the study period, representative of a significant proportion of the North Island population. Seasonal abundance estimates peaked in summer and autumn and were lower during winter months, with individuals leaving the study area for multiple seasons but subsequently returning. Thus, individuals of the North Island population clearly spend extended periods of time outside of what has formerly been recognised as their core home range. It is apparent that the GBI region is not simply being used as a corridor to reach other destinations but instead is a key location for at least a part of the North Island population. A number of important baselines have been identified via this study and the future challenge will lie in securing enough resources to ensure continuity in research and monitoring for further conservation purposes. The fact that the use of GBI waters by bottlenose dolphins has been overlooked until now highlights the need for researchers, managers and funding agencies to maintain an open outlook on their population of interest as a whole when conducting or funding research. For management of North Island bottlenose dolphins to be effective, a comprehensive approach including the entire home range of this population along the northeast coast is required. This research also demonstrated for the first time that occupancy models can be successfully applied to cetacean sighting data to assess habitat use while simultaneously accounting for imperfect detection. There was strong agreement between predicted areas of high use for common dolphins identified by the GLMs and occupancy models. This congruency between different model types suggests that the predictive maps presented here provide reliable seasonal distributional information that will be useful to support current and future conservation initiatives. An improved understanding of the processes driving the differences in habitat use will enable refined predictions of spatial and temporal distribution, which is required for effective management and conservation of cetaceans using the Hauraki Gulf.