scholarly journals Food provisioning increases the risk of injury in a long-lived marine top predator

2016 ◽  
Vol 3 (12) ◽  
pp. 160560 ◽  
Author(s):  
Fredrik Christiansen ◽  
Katherine A. McHugh ◽  
Lars Bejder ◽  
Eilidh M. Siegal ◽  
David Lusseau ◽  
...  
Keyword(s):  
Prey Availability ◽  
Bottlenose Dolphins ◽  
Population Level ◽  
Food Provisioning ◽  
Contributing Factors ◽  
Human Interactions ◽  
Sarasota Bay ◽  
Dolphin Population ◽  
Spatio Temporal

Food provisioning of wildlife is a major concern for management and conservation agencies worldwide because it encourages unnatural behaviours in wild animals and increases each individual's risk for injury and death. Here we investigate the contributing factors and potential fitness consequences of a recent increase in the frequency of human interactions with common bottlenose dolphins ( Tursiops truncatus ) in Sarasota Bay, Florida. A rising proportion of the local long-term resident dolphin community is becoming conditioned to human interactions through direct and indirect food provisioning. We investigate variables that are affecting conditioning and if the presence of human-induced injuries is higher for conditioned versus unconditioned dolphins. Using the most comprehensive long-term dataset available for a free-ranging bottlenose dolphin population (more than 45 years; more than 32 000 dolphin group sightings; more than 1100 individuals), we found that the association with already conditioned animals strongly affected the probability of dolphins becoming conditioned to human interactions, confirming earlier findings that conditioning is partly a learned behaviour. More importantly, we found that conditioned dolphins were more likely to be injured by human interactions when compared with unconditioned animals. This is alarming, as conditioning could lead to a decrease in survival, which could have population-level consequences. We did not find a significant relationship between human exposure or natural prey availability and the probability of dolphins becoming conditioned. This could be due to low sample size or insufficient spatio-temporal resolution in the available data. Our findings show that wildlife provisioning may lead to a decrease in survival, which could ultimately affect population dynamics.

Pregnancy Cravings: Visitation at a Food-Provisioning Site is Driven by the Reproductive Status of Bottlenose Dolphins

2020 ◽  
Vol 15 (3) ◽  
pp. 237-248
Author(s):  
Valeria Senigaglia ◽  
Lars Bejder
Keyword(s):  
Prey Availability ◽  
Southern Oscillation ◽  
Bottlenose Dolphins ◽  
Reproductive Status ◽  
Food Provisioning ◽  
Human Interactions ◽  
Increase Risk ◽  
Lactating Females ◽  
Tourism Attractions ◽  
Marine Wildlife

Marine wildlife tourism attractions often use food rewards to ensure close-up encounters with freeranging animals. In Bunbury, Western Australia, the Dolphin Discovery Centre (DDC) conducts a foodprovision program where bottlenose dolphins (N = 22; between 2000 and 2018) are offered food rewards to encourage their visitation at a beach in front of the DDC. We used historical records on individual beach visits by adult female dolphins collected by the DDC from 2000 to 2018 to develop generalized mixed effects models (GLMM) to test whether the frequency of beach visitation was influenced by their reproductive status (pregnant, lactating, nonreproductive) or climatic events (El Niño-Southern Oscillation phases) that could affect prey availability. We also quantified the behavioral budget of dolphins during food-provisioning sessions and documented intra- and interspecific aggressive behaviors using individual focal follows collected in 2017–2018. Provisioned females spend most of the time resting within the interaction area (66.3%) and aggressive interactions arise as a consequence of dominance behavior over food access. Visitation rates were most influenced by reproductive status with pregnant and lactating females visiting the provisioning area more frequently (z = 2.085, p = 0.037 and z = 2.437, p = 0.014, respectively). Females that frequently visit the provisioning area expose their dependent calves to regular human interactions at an early age when they are more susceptible to behavioral conditioning. Such experiences could cause the loss of awareness towards humans and promote maladaptive behaviors such as begging that increase risk of entanglement in fishing gear, boat strikes, and propeller injuries.

scholarly journals Predictors of invertebrate biomass and rate of advancement of invertebrate phenology across eight sites in the North American Arctic

Polar Biology ◽  
2021 ◽  
Vol 44 (2) ◽  
pp. 237-257
Author(s):  
Rebecca Shaftel ◽  
Daniel J. Rinella ◽  
Eunbi Kwon ◽  
Stephen C. Brown ◽  
H. River Gates ◽  
...  
Keyword(s):  
Prey Availability ◽  
Population Level ◽  
The Arctic ◽  
Environmental Drivers ◽  
Chick Survival ◽  
The North ◽  
Phenological Mismatch ◽  
Nesting Sites ◽  
North American Arctic

AbstractAverage annual temperatures in the Arctic increased by 2–3 °C during the second half of the twentieth century. Because shorebirds initiate northward migration to Arctic nesting sites based on cues at distant wintering grounds, climate-driven changes in the phenology of Arctic invertebrates may lead to a mismatch between the nutritional demands of shorebirds and the invertebrate prey essential for egg formation and subsequent chick survival. To explore the environmental drivers affecting invertebrate availability, we modeled the biomass of invertebrates captured in modified Malaise-pitfall traps over three summers at eight Arctic Shorebird Demographics Network sites as a function of accumulated degree-days and other weather variables. To assess climate-driven changes in invertebrate phenology, we used data from the nearest long-term weather stations to hindcast invertebrate availability over 63 summers, 1950–2012. Our results confirmed the importance of both accumulated and daily temperatures as predictors of invertebrate availability while also showing that wind speed negatively affected invertebrate availability at the majority of sites. Additionally, our results suggest that seasonal prey availability for Arctic shorebirds is occurring earlier and that the potential for trophic mismatch is greatest at the northernmost sites, where hindcast invertebrate phenology advanced by approximately 1–2.5 days per decade. Phenological mismatch could have long-term population-level effects on shorebird species that are unable to adjust their breeding schedules to the increasingly earlier invertebrate phenologies.

Assessing variation in assemblages of large marine fauna off ocean beaches using drones

2020 ◽  
Vol 71 (1) ◽  
pp. 68 ◽  
Author(s):  
Brendan P. Kelaher ◽  
Andrew P. Colefax ◽  
Alejandro Tagliafico ◽  
Melanie J. Bishop ◽  
Anna Giles ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Bottlenose Dolphins ◽  
Spatial And Temporal Variation ◽  
Marine Animals ◽  
Marine Fauna ◽  
South Wales ◽  
Carcharhinus Leucas ◽  
Spatio Temporal ◽  
Marine Wildlife

The turbulent waters off ocean beaches provide habitat for large marine fauna, including dolphins, sharks, rays, turtles and game fish. Although, historically, these assemblages have proven difficult to quantify, we used a new drone-based approach to assess spatial and temporal variation in assemblages of large marine fauna off four exposed beaches in New South Wales, Australia. In total, 4388 individual large marine animals were identified from 216 drone flights. The most common taxa, bottlenose dolphins (Tursiops spp.) and Australian cownose rays (Rhinoptera neglecta), occurred in 25.5 and 19.9% of flights respectively. White (Carcharodon carcharias), bull (Carcharhinus leucas) and other whaler (Carcharhinus spp.) sharks were observed in <1% of flights. There was significant variation in the structure of assemblages of large fauna among beaches, with those adjacent to riverine estuaries having greater richness and abundance of wildlife. Overall, drone surveys were successful in documenting the spatio-temporal dynamics of an impressive suite of large marine fauna. We contend that emerging drone technology can make a valuable contribution to the ecological information required to ensure the long-term sustainability of sandy-beach ecosystems and associated marine wildlife.

Suitability of a young deciduous-dominated forest for American marten and the effects of forest removal

2004 ◽  
Vol 82 (3) ◽  
pp. 423-435 ◽  
Author(s):  
Kim G Poole ◽  
Aswea D Porter ◽  
Andrew de Vries ◽  
Chris Maundrell ◽  
Scott D Grindal ◽  
...  
Keyword(s):  
Populus Tremuloides ◽  
Forest Cover ◽  
Agricultural Land ◽  
Prey Availability ◽  
Population Level ◽  
Home Ranges ◽  
American Marten ◽  
Individual Level ◽  
The Individual

American marten (Martes americana (Turton, 1806)) are generally considered to be reliant upon and most successful in continuous late-successional coniferous forests. By contrast, young seral forests and deciduous-dominated forests are assumed to provide low-quality marten habitat, primarily as a result of insufficient structure, overhead cover, and prey. This study examined a moderate-density population of marten in northeastern British Columbia in what appeared to be comparatively low-quality, deciduous-dominated habitat, overgrown agricultural land primarily consisting of 30- to 40-year-old stands of regenerating trembling aspen (Populus tremuloides Michx.). Over 4 years, we monitored 52 radio-collared marten. The population appeared to be stable, as indicated by large numbers of adults, relatively constant densities, long-term residency of many individuals, low mortality rates, and older age structure. Relatively small home ranges (males, 3.3 km2; females, 2.0 km2) implied good habitat quality and prey availability. Shearing (removal of immature forest cover) of 17% of the study area resulted in home range shifts at the individual level but no detectable impact at the population level. Categorically, marten avoided nonforested cover types and preferred mature coniferous (>25% conifer) stands (7% of the study area) but otherwise appeared to use all forested stands relative to their availability, including extensive use of deciduous-dominated stands and deciduous stands <40 years of age. Thus, these young deciduous forests appeared to have sufficient structure, overhead cover, and prey to maintain moderate densities of resident marten on a long-term basis.

scholarly journals How to Work on a Non-endangered Species and Contribute to Cetacean Conservation: An Example by the Sarasota Dolphin Research Program

2021 ◽  
Vol 8 ◽  
Author(s):  
Frances M. D. Gulland
Keyword(s):  
Endangered Species ◽  
Research Program ◽  
Bottlenose Dolphins ◽  
Cetacean Species ◽  
Sarasota Bay ◽  
Conservation Actions ◽  
Data Deficient ◽  
Iucn Red Data List ◽  
Term Data

The world’s most endangered small cetaceans are found in countries many miles from Sarasota Bay and its common bottlenose dolphins (Tursiops truncatus). Information on the ecology and threats to many of these endangered cetaceans is often far more limited than that on bottlenose dolphins, with the IUCN Red Data List describing many species as “data deficient.” In many developing nations where these rare species occur, resources for research and monitoring are scant, and logistical challenges further limit research into marine mammal health and population status and their threats. The Sarasota Dolphin Research Program (SDRP) has tackled this problem by using the bottlenose dolphin as a model for cetacean species in other parts of the world and using its resources to assist scientists working with more endangered species of cetacean. The celebration of 50 years of study by the SDRP exemplifies how using long-term data on known individuals can advance the fields of cetacean behavior, ecology, life history, physiology, toxicology, and medicine, all providing information for informing certain conservation actions. The Sarasota team has used their work to inform conservation policy both home and abroad.

scholarly journals Body Composition of Common Bottlenose Dolphins in Sarasota Bay, Florida

2021 ◽  
Vol 8 ◽  
Author(s):  
Stephanie K. Adamczak ◽  
Rachel R. Holser ◽  
Daniel P. Costa ◽  
Elizabeth J. Berens McCabe ◽  
Randall S. Wells
Keyword(s):  
Body Composition ◽  
Prey Availability ◽  
Bottlenose Dolphins ◽  
The Body ◽  
Catch Per Unit Effort ◽  
Young Males ◽  
Young Females ◽  
Common Bottlenose Dolphin ◽  
Significant Difference ◽  
Sarasota Bay

Marine mammal body composition has been an important tool that is used as a proxy for the health and condition of individuals within a population. Common bottlenose dolphin (Tursiops truncatus) body composition is influenced by variations in blubber thickness resulting from changes in temperature, prey availability, health, and life-history traits. We examined how environmental, ontogenetic, and reproductive variables influenced the body composition of common bottlenose dolphins in Sarasota Bay using data collected from a long-term monitoring project by the Sarasota Dolphin Research Program (SDRP). We found that both sea surface temperature (SST) and catch per unit effort (CPUE), used as a proxy for prey availability, influenced body composition. There was a high degree of seasonality in body composition, with higher values occurring in winter when SST and CPUE were both low. Ontogeny also greatly influenced body composition, as younger dolphins typically had thicker blubber than mature individuals. Interestingly, young females allocated more energy to allometric growth than deposition of blubber for body composition when compared to young males. However, as females matured and their growth slowed, they invested more in body composition. We found no significant difference in body composition of females of varying reproductive states, providing further evidence of their status as true income breeders. Our work highlights that changes in body composition result from fluctuations in environmental variables and that energy allocation to body composition changes with ontogeny.

scholarly journals Habitat complexity and lifetime predation risk influence mesopredator survival in a multi-predator system

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Laura C. Gigliotti ◽  
Rob Slotow ◽  
Luke T. B. Hunter ◽  
Julien Fattebert ◽  
Craig Sholto-Douglas ◽  
...  
Keyword(s):  
Habitat Selection ◽  
Habitat Use ◽  
Predation Risk ◽  
Prey Availability ◽  
Scale Up ◽  
Population Level ◽  
Apex Predators ◽  
Acinonyx Jubatus ◽  
Selection Of

Abstract Variability in habitat selection can lead to differences in fitness; however limited research exists on how habitat selection of mid-ranking predators can influence population-level processes in multi-predator systems. For mid-ranking, or mesopredators, differences in habitat use might have strong demographic effects because mesopredators need to simultaneously avoid apex predators and acquire prey. We studied spatially-explicit survival of cheetahs (Acinonyx jubatus) in the Mun-Ya-Wana Conservancy, South Africa, to test hypotheses related to spatial influences of predation risk, prey availability, and vegetation complexity, on mesopredator survival. For each monitored cheetah, we estimated lion encounter risk, prey density, and vegetation complexity within their home range, on short-term (seasonal) and long-term (lifetime) scales and estimated survival based on these covariates. Survival was lowest for adult cheetahs and cubs in areas with high vegetation complexity on both seasonal and lifetime scales. Additionally, cub survival was negatively related to the long-term risk of encountering a lion. We suggest that complex habitats are only beneficial to mesopredators when they are able to effectively find and hunt prey, and show that spatial drivers of survival for mesopredators can vary temporally. Collectively, our research illustrates that individual variation in mesopredator habitat use can scale-up and have population-level effects.

scholarly journals Bias, incompleteness and the ‘known unknowns’ in the Holocene faunal record

2019 ◽  
Vol 374 (1788) ◽  
pp. 20190216 ◽  
Author(s):  
Jennifer J. Crees ◽  
Ben Collen ◽  
Samuel T. Turvey
Keyword(s):  
Fossil Record ◽  
Extinction Risk ◽  
Population Level ◽  
Sampling Bias ◽  
Error Type ◽  
The Holocene ◽  
Continental Population ◽  
Spatio Temporal ◽  
Known Unknowns

Long-term faunal data are needed to track biodiversity change and extinction over wide spatio-temporal scales. The Holocene record is a particularly rich and well-resolved resource for this purpose but nonetheless represents a biased subset of the original faunal composition, both at the site-level assemblage and when data are pooled for wider-scale analysis. We investigated patterns and potential sources of taxonomic, spatial and temporal bias in two Holocene datasets of mammalian occurrence and abundance, one at the global species level and one at the continental population-level. Larger-bodied species are disproportionately abundant in the Holocene fossil record, but this varies according to trophic level, probably owing to past patterns of human subsistence and exploitation. Despite the uneven spatial distribution of mammalian occurrence records, we found no specific source of sampling bias, suggesting that this error type can be avoided by intensive data collection protocols. Faunal assemblages are more abundant and precisely dated nearer to the present as a consequence of taphonomy, past human demography and dating methods. Our study represents one of the first attempts to quantify incompleteness and bias in the Holocene mammal record, and failing to critically assess the quality of long-term faunal datasets has major implications for understanding species decline and extinction risk. This article is part of a discussion meeting issue ‘The past is a foreign country: how much can the fossil record actually inform conservation?’

scholarly journals Food-provisioning negatively affects calf survival and female reproductive success in bottlenose dolphins

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
V. Senigaglia ◽  
F. Christiansen ◽  
K. R. Sprogis ◽  
J. Symons ◽  
L. Bejder
Keyword(s):  
Reproductive Success ◽  
Bayes Factor ◽  
Linear Models ◽  
Southern Oscillation ◽  
Bottlenose Dolphins ◽  
Food Provisioning ◽  
Female Reproductive Success ◽  
Climatic Fluctuations ◽  
Calf Survival

AbstractFood-provisioning of wildlife can facilitate reliable up-close encounters desirable by tourists and, consequently, tour operators. Food-provisioning can alter the natural behavior of an animal, encouraging adverse behavior (e.g. begging for food handouts), and affect the reproductive success and the viability of a population. Studies linking food-provisioning to reproductive success are limited due to the lack of long-term datasets available, especially for long-lived species such as marine mammals. In Bunbury, Western Australia, a state-licensed food-provisioning program offers fish handouts to a limited number of free-ranging bottlenose dolphins (Tursiops aduncus). Coupled with long-term historical data, this small (<200 individuals), resident dolphin population has been extensively studied for over ten years, offering an opportunity to examine the effect of food-provisioning on the reproductive success of females (ntotal = 63;nprovisioned females = 8). Female reproductive success was estimated as the number of weaned calves produced per reproductive years and calf survival at year one and three years old was investigated. The mean reproductive success of provisioned and non-provisioned females was compared using Bayes factor. We also used generalized linear models (GLMs) to examine female reproductive success in relation to the occurrence of food-provisioning, begging behavior and location (within the study area). Furthermore, we examined the influence of these variables and birth order and climatic fluctuations (e.g. El Niño Southern Oscillation) on calf survival. Bayes factor analyses (Bayes factor = 6.12) and results from the best fitting GLMs showed that female reproductive success and calf survival were negatively influenced by food-provisioning. The negative effects of food-provisioning, although only affecting a small proportion of the adult females’ population (13.2%), are of concern, especially given previous work showing that this population is declining.

Cranial crassicaudiasis in two coastal dolphin species from South Africa is predominantly a disease of immature individuals

2020 ◽  
Vol 139 ◽  
pp. 93-102 ◽  
Author(s):  
MF Van Bressem ◽  
P Duignan ◽  
JA Raga ◽  
K Van Waerebeek ◽  
N Fraijia-Fernández ◽  
...  
Keyword(s):  
South Africa ◽  
Bone Development ◽  
Bottlenose Dolphins ◽  
Fatal Outcome ◽  
Population Level ◽  
Cape Coast ◽  
Osteolytic Lesions ◽  
Immune Mediated ◽  
Significant Difference ◽  
The Difference

Crassicauda spp. (Nematoda) infest the cranial sinuses of several odontocetes, causing diagnostic trabecular osteolytic lesions. We examined skulls of 77 Indian Ocean humpback dolphins Sousa plumbea and 69 Indo-Pacific bottlenose dolphins Tursiops aduncus, caught in bather-protecting nets off KwaZulu-Natal (KZN) from 1970-2017, and skulls of 6 S. plumbea stranded along the southern Cape coast in South Africa from 1963-2002. Prevalence of cranial crassicaudiasis was evaluated according to sex and cranial maturity. Overall, prevalence in S. plumbea and T. aduncus taken off KZN was 13 and 31.9%, respectively. Parasitosis variably affected 1 or more cranial bones (frontal, pterygoid, maxillary and sphenoid). No significant difference was found by gender for either species, allowing sexes to be pooled. However, there was a significant difference in lesion prevalence by age, with immature T. aduncus 4.6 times more likely affected than adults, while for S. plumbea, the difference was 6.5-fold. As severe osteolytic lesions are unlikely to heal without trace, we propose that infection is more likely to have a fatal outcome for immature dolphins, possibly because of incomplete bone development, lower immune competence in clearing parasites or an over-exuberant inflammatory response in concert with parasitic enzymatic erosion. Cranial osteolysis was not observed in mature males (18 S. plumbea, 21 T. aduncus), suggesting potential cohort-linked immune-mediated resistance to infestation. Crassicauda spp. may play a role in the natural mortality of S. plumbea and T. aduncus, but the pathogenesis and population level impact remain unknown.

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