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

Abstract

Food-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.

Tourism, Empowerment and Sustainable Development: A New Framework for Analysis

“…Too often tourism has contributed to damage to marine life, whether by mangrove removal to reclaim more coastal land for construction [83,84], hotels and cruise ships discharging waste into the water [85], or habituation of dolphins through provisioning [86]. Similarly, overcrowding of tourism sites along with inadequate provision of infrastructure can lead to degradation of flora and fauna.…”

Elevated Calf Mortality and Long-Term Responses of Wild Bottlenose Dolphins to Extreme Climate Events: Impacts of Foraging Specialization and Provisioning

“…However, provisioned adult females had similar behavioral activity budgets to non-provisioned females when they were away from the human interaction area. At another provisioning site, in Bunbury, Western Australia, female calving success was also negatively impacted by provisioning (Senigaglia et al, 2019), presumably from harmful interactions with humans (such as boat begging), rarely engaged in by non-provisioned dolphins (Mann et al, 2018). At the third bottlenose dolphin site, in Tangalooma, Australia, calf survival was reported to be 100% with few deleterious impacts of provisioning (Neil and Holmes, 2008) other than aggressive behavior toward humans (Orams et al, 1996).…”

Morphological differences between coastal bottlenose dolphin (Tursiops aduncus) populations identified using non-invasive stereo-laser photogrammetry

“…The SWMRP has identified approximately 500 individual dolphins, facilitating the development of a long-term demographic dataset comprising of photo-identification 64 , demographic (age and sex) 65 and sighting-history information (Supplementary Table S5). Additional photo-identification, demographic and sighting data have been obtained on food-provisioned dolphins since 1989, following the establishment of a not-for-profit dolphin-tourism centre conducting dolphin-provisioning and eco-tours 66 .…”