Side effects of contraceptive treatment

The efficacy of contraceptive treatments has been extensively tested, and several formulations are effective at reducing fertility in a range of species. However, these formulations should minimally impact the behaviour of individuals and populations before a contraceptive is used for population manipulation, but these effects have received less attention. Potential side effects have been identified theoretically and we reviewed published studies that have investigated side effects on behaviour and physiology of individuals or population-level effects, which provided mixed results. Physiological side effects were most prevalent. Most studies reported a lack of secondary effects, but were usually based on qualitative data or anecdotes. A meta-analysis on quantitative studies of side effects showed that secondary effects consistently occur across all categories and all contraceptive types. This contrasts with the qualitative studies, suggesting that anecdotal reports are insufficient to investigate secondary impacts of contraceptive treatment. We conclude that more research is needed to address fundamental questions about secondary effects of contraceptive treatment and experiments are fundamental to conclusions. In addition, researchers are missing a vital opportunity to use contraceptives as an experimental tool to test the influence of reproduction, sex and fertility on the behavior of wildlife species.This work was supported by the Nevada Arid Rangeland Initiative (grant numbers NOA15353CG, 110615253BS, 140115253BS, 140215253BS) and Hatch Grant (grant number 13215353BS).http://www.srf-reproduction.org

Spotted hyaena space use in relation to human infrastructure inside a protected area

Increasing human population growth has led to elevated levels of human-carnivore conflict. However, some carnivore populations have adapted to urban environments and the resources they supply. Such associations may influence carnivore ecology, behaviour and life-history. Pockets of urbanisation sometimes occur within protected areas, so that anthropogenic influences on carnivore biology are not necessarily confined to unprotected areas. In this study we evaluated associations between human infrastructure and related activity and space use of spotted hyaenas within one of the largest protected areas in South Africa, the Kruger National Park. Home range size was smaller for the dominant female of a clan living in close proximity to humans than that of the dominant female of a clan without direct access to human infrastructure. The home range including human infrastructure was also used less evenly during the night, presumably when the animals were active. Within this home range, a village area was preferred during the night, when the least modified areas within the village were preferred and administration and highly modified areas were avoided. During the day, however, there were no preference or avoidance of the village area, but all habitats except unmodified habitats within the village area were avoided.Wesuggest that human infrastructure and associated activity influenced hyaena space use, primarily through alterations in the spatial distribution of food. However, these effects may have been indirectly caused by habitat modification that generated favourable hunting habitat rather than a direct effect caused by access to human food such as garbage. Because of the often pivotal effects of apex predators in terrestrial ecosystems, we encourage further work aimed to quantify how human presence influences large carnivores and associated ecosystem processes within protected areas.Supplement 1. Estimation of convergence of home range size estimates. To evaluate whether or not we had sufficient sample sizes to estimate seasonal home ranges we created accumulation curves for each clan and season. We created randomized sets of coordinates with increasing sample sizes from 10 relocations up to the actual sample size used for each seasonal range. For each sample size, we randomly drew 100 data sets without replacements from the original sets of coordinates that was utilized to calculate each seasonal home range, and for each random data set we calculated the area covered by a 100% MCP. These areas were plotted against sample size. (10.7717/peerj.2596/supp-1)Supplement 2. Raw data on animal locations. (DOI: 10.7717/peerj.2596/supp-2)This study was funded through incentive funding for rated researchers by the National Research Foundation (E Cameron, F Dalerum), a research fellowship from University of Pretoria (F Dalerum) as well as a Ramón y Cajal fellowship by the Spanish Ministry of Comptitiveness and Economy (F Dalerum).https://peerj.comam2017Mammal Research InstituteZoology and Entomolog

Spotted hyaena space use in relation to human infrastructure inside a protected area

Increasing human population growth has led to elevated levels of human-carnivore conflict. However, some carnivore populations have adapted to urban environments and the resources they supply. Such associations may influence carnivore ecology, behaviour and life-history. Pockets of urbanisation sometimes occur within protected areas, so that anthropogenic influences on carnivore biology are not necessarily confined to unprotected areas. In this study we evaluated associations between human infrastructure and related activity and space use of spotted hyaenas within one of the largest protected areas in South Africa, the Kruger National Park. Home range size was smaller for the dominant female of a clan living in close proximity to humans than that of the dominant female of a clan without direct access to human infrastructure. The home range including human infrastructure was also used less evenly during the night, presumably when the animals were active. Within this home range, a village area was preferred during the night, when the least modified areas within the village were preferred and administration and highly modified areas were avoided. During the day, however, there were no preference or avoidance of the village area, but all habitats except unmodified habitats within the village area were avoided.Wesuggest that human infrastructure and associated activity influenced hyaena space use, primarily through alterations in the spatial distribution of food. However, these effects may have been indirectly caused by habitat modification that generated favourable hunting habitat rather than a direct effect caused by access to human food such as garbage. Because of the often pivotal effects of apex predators in terrestrial ecosystems, we encourage further work aimed to quantify how human presence influences large carnivores and associated ecosystem processes within protected areas.Supplement 1. Estimation of convergence of home range size estimates. To evaluate whether or not we had sufficient sample sizes to estimate seasonal home ranges we created accumulation curves for each clan and season. We created randomized sets of coordinates with increasing sample sizes from 10 relocations up to the actual sample size used for each seasonal range. For each sample size, we randomly drew 100 data sets without replacements from the original sets of coordinates that was utilized to calculate each seasonal home range, and for each random data set we calculated the area covered by a 100% MCP. These areas were plotted against sample size. (10.7717/peerj.2596/supp-1)Supplement 2. Raw data on animal locations. (DOI: 10.7717/peerj.2596/supp-2)This study was funded through incentive funding for rated researchers by the National Research Foundation (E Cameron, F Dalerum), a research fellowship from University of Pretoria (F Dalerum) as well as a Ramón y Cajal fellowship by the Spanish Ministry of Comptitiveness and Economy (F Dalerum).https://peerj.comam2017Mammal Research InstituteZoology and Entomolog

Behavioural and endocrine correlates to the aardwolf mating system

It is now widely recognized that mating systems contain both social and genetic components, where social components describe patterns of social associations while genetic components reflect patterns of mating activities. In many species these two components do not coincide. If the level of sexual asymmetry differs between these two components, for instance in monogamous pairs with high levels of infidelity, each component may impose different selection pressures on behavioural and physiological characteristics. However, we have limited knowledge of how social and genetic components influence behaviour and physiology. The aardwolf (Proteles cristata) is a small insectivorous hyaenid, which has been described as socially monogamous but sexually promiscuous. In this study, we evaluated if aardwolf space use, scent marking, foraging behaviour and endocrine fluctuations relate to predictions from social monogamy or polygamous mating. Our results did not show sex differences in behaviour or physiology that would be consistent with predictions from polygamous mating, and we suggest that social mate associations may regulate the observed endocrine and behavioural parameters more than actual mating patterns in this species. Such an interpretation would suggest that the fitness effect of promiscuous mating may be low, since it appears to impose little selection pressure on mating related behaviour. We stress that it is then unclear how promiscuous mating is maintained in this socially monogamous species.The study was financially supported by an NRF focal area grant (EZC,grant number AA895595), NRF incentive funds (FD), an NRF SARCHi chair in mammal behavioural ecology and physiology awarded to Prof. Nigel Bennett and a research fellowship from University of Pretoria (FD).http://www.elsevier.com/locate/mambiohb201

Transforming encounters: A review of the drivers and mechanisms of macrofaunal plastic fragmentation in the environment

Plastic has infiltrated every ecosystem on the planet, making encounters between this anthropogenic pollutant and fauna inevitable. Abiotic environmental breakdown involving light, oxygen, temperature and mechanical forces is well-characterized, while biotic degradation mechanisms are less well-understood. Reports of the role of macrofauna in the fragmentation of plastic debris are increasing. This review explores the driving factors for macrofaunal fragmentation, as well as the physiological mechanisms by which plastic items are fragmented. The presence, and access to plastic within an organism’s habitat are the key determinants of macrofaunal plastic degradation. Foraging strategies, along with burrowing and nesting behaviors increase the likelihood of macrofauna interacting with plastics. Though this type of fragmentation can occur externally, it often follows ingestion, which in itself can be driven by resemblance to food. Four physical mechanisms of macrofaunal plastic fragmentation were identified, namely biting, drilling, grazing and grinding. Biting, restricted to the mouthparts of an organism, was the most common form of macrofaunal fragmentation reported in literature. Similarly, the use of specialized mouthparts for drilling or grazing can produce secondary plastic particles. Lastly, grinding, through manipulation by the gizzard or gastric mill following ingestion can significantly reduce the size of the plastic material. Prolonged and/or repeated interactions with plastics pose the risk of increased wear on the mouthparts and digestive organs involved. Through mechanisms that directly affect the plastic’s structural integrity, physical fragmentation by macrofauna can amplify overall plastic degradation rates and the formation of micro- and nanoplastics in the environment, while long internal retention times can contribute to their dispersal, trophic transfer, and the organism’s exposure to plastic additives. To more fully understand the extent of macrofaunal plastic fragmentation and allow predictive modeling, we suggest the reporting of evidence in a unified and systematic way. Our findings further highlight the urgency for the implementation of a global plastic waste management system to reduce the burden of micro- and nanoplastics

Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus)

The occurrence of stress-inducing factors in captive crocodilians is a concern, since chronic stress can negatively affect animal health and reproduction, and hence production. Monitoring stress in wild crocodiles could also be beneficial for assessing the state of health in populations which are potentially threatened by environmental pollution. In both cases, a non-invasive approach to assess adrenocortical function as a measure of stress would be preferable, as animals are not disturbed during sample collection, and therefore sampling is feedback-free. So far, however, such a non-invasive method has not been established for any crocodilian species. As an initial step,we therefore examined the suitability of two enzyme-immunoassays, detecting faecal glucocorticoid metabolites (FGMs) with a 11β,21-diol-20-one and 5β-3α-ol-11-one structure, respectively, for monitoring stress-related physiological responses in captive Nile crocodiles (Crocodylus niloticus). An adrenocorticotropic hormone (ACTH) challenge was performed on 10 sub-adult crocodiles, resulting in an overall increase in serum corticosterone levels of 272% above the pre-injection levels 5 h post-injection. Saline-treated control animals (n=8) showed an overall increase of 156% in serum corticosterone levels 5 h post-administration. Faecal samples pre- and post-injection could be obtained from three of the six individually housed crocodiles, resulting in FGMconcentrations 136–380% above pre-injection levels, always detected in the first sample collected post-treatment (7–15 days post-injection). FGM concentrations seem comparatively stable at ambient temperatures for up to 72 h post-defaecation. In conclusion, non-invasive hormone monitoring can be used for assessing adrenocortical function in captive Nile crocodiles based on FGM analysis.University of Pretoria.The IUCN-SSC Crocodile Specialist Group (SRAS Project 10/12) and Novartis/SAVF Wildlife Research Fundhttp://www.elsevier.com/locate/cbpahb201

Sex ratio variation in a eusocial mammal, the Damaraland mole-rat, Fukomys damarensis

Sex allocation theory predicts that mothers benefit from adjusting the sex ratio of their offspring in relation to their offspring's future reproductive success. In cooperative breeders, parents are expected to bias the sex ratio in relation to their current need for help and the benefit received from helpers of each sex as proposed by the local resource enhancement (LRE) and helper repayment hypotheses (HR). Consequently, as group size increases, sex ratios are expected to be biased towards the sex that is more likely to disperse to avoid competition as proposed in the local resource competition hypothesis (LRC). The current study aimed to investigate helper effects on breeder fecundity and offspring sex ratio adjustments in a eusocial mammal the Damaraland mole-rat Fukomys damarensis. Both sexes equally contribute to helping in this species, but breeding dispersal is male biased. We found no evidence for helper effects on maternal body mass and litter size. Offspring sex ratio was not affected by maternal mass or litter size. However, the probability of male pups to be born increased with the number of female helpers and decreased with the number of male helpers. In addition, the number of male pups in a litter increased significantly with the number of female but not male helpers, while no helper effects were apparent for the number of female pups born. Hence, our data suggest that the mechanisms underlying the LRE, HR and LRC may operate simultaneously in the study species.The National Research Foundation and the University of Pretoria.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-79982015-10-30hj201

Spatial and temporal dimensions to the taxonomic diversity of arthropods in an arid grassland savannah

Quantifying the drivers of biodiversity variation is a key topic in contemporary ecology. While the geographic distribution of biodiversity is broadly determined by water and energy, local environmental conditions may be important. We evaluated the relative effects of spatial and temporal variation on taxonomic diversity of ground living arthropod communities in central South Africa. Seasonal climate variation was a major driver of arthropod abundance, but seasonal effects differed between habitats. We did not find any evidence for modular community structures, even across different habitats, or any evidence for a nested pattern across seasons. Instead, we observed a spatial nestedness which was only partly related to specific habitats. Our results suggest that neutral processes had influenced arthropod community structure, but also that very local processes may have been pivotal in determining local and regional arthropod diversity. Such processes may not necessarily have been neutral, but could have been caused by niche deterministic processes acting at scales smaller the distinct habitat classes we used for our study. We further suggest that alterations in climate likely will have substantial effects on the spatial and temporal distribution of arthropod diversity in this arid region.The South African Research Chair Initiative chair of Mammal Behavioural Ecology and Physiology - National Research Foundation (NRF), the University of Pretoria and the Spanish Ministry of Competitiveness and Economy.http://www.elsevier.com/locate/jaridenv2018-09-30hj2017Mammal Research InstituteZoology and Entomolog

Multi-year fertility reduction in free-roaming feral horses with single-injection immunocontraceptive formulations

Abstract Context. Contraception is increasingly used as a management technique to reduce fertility in wildlife populations; however, the feasibility of contraceptive formulations has been limited until recently because they have required multiple treatments to achieve prolonged infertility. Aims. We tested the efficacy and evaluated potential side effects of two contraceptive formulations, a porcine zona pellucida (PZP) formulation, SpayVac ® and a gonadotrophin-releasing hormone (GnRH) formulation GonaCon-BÔ, in a population of free-roaming feral horses (Equus caballus). Both formulations were developed to provide several years of infertility with one injection. Methods. Females were treated in June 2005 with either GonaCon-B (n = 24), SpayVac (n = 20), adjuvant only (n = 22), or received no injection (n = 18). Females were monitored for fertility status year round for 3 years after treatment. Key results. Both contraceptive treatments significantly reduced fertility for 3 years. Fertility rates for GonaCon-B mares were 39%, 42% and 31%, respectively, and 37%, 50% and 44% for SpayVac mares. During the same seasons, 61%, 67% and 76% of control females were fertile. We found no significant effects from contraceptive treatment on the sex ratio of foals, birthing season or foal survival. Conclusions. These results demonstrated that both vaccines are capable of significantly reducing fertility for several years without boosters. Implications. Contraceptive vaccines examined in the present study represent a useful tool for the management of feral horses, because of their being efficacious for 3 years in the absence of booster immunisations

Devil Declines and Catastrophic Cascades: Is Mesopredator Release of Feral Cats Inhibiting Recovery of the Eastern Quoll?

The eastern quoll (Dasyurus viverrinus) is a medium-sized Australian marsupial carnivore that has recently undergone a rapid and severe population decline over the 10 years to 2009, with no sign of recovery. This decline has been linked to a period of unfavourable weather, but subsequent improved weather conditions have not been matched by quoll recovery. A recent study suggested another mechanism: that declines in Tasmanian devil (Sarcophilus harrisii) populations, due to the spread of the fatal Devil Facial Tumour Disease, have released feral cats (Felis catus) from competitive suppression, with eastern quoll declines linked to a subsequent increase in cat sightings. Yet current evidence of intraguild suppression among devils, cats and quolls is scant and equivocal. We therefore assessed the influences of top-down effects on abundance and activity patterns among devils, feral cats and eastern quolls. Between 2011 and 2013, we monitored four carnivore populations using longitudinal trapping and camera surveys, and performed camera surveys at 12 additional sites throughout the eastern quoll's range. We did not find evidence of a negative relationship between devil and cat abundance, nor of higher cat abundance in areas where devil populations had declined the longest. Cats did not appear to avoid devils spatially; however, there was evidence of temporal separation of cat and devil activity, with reduced separation and increasing nocturnal activity observed in areas where devils had declined the longest. Cats and quolls used the same areas, and there was no evidence that cat and quoll abundances were negatively related. Temporal overlap in observed cat and quoll activity was higher in summer than in winter, but this seasonal difference was unrelated to devil declines. We suggest that cats did not cause the recent quoll decline, but that predation of juvenile quolls by cats could be inhibiting low density quoll populations from recovering their former abundance through a 'predator pit' effect following weather-induced decline. Predation intensity could increase further should cats become increasingly nocturnal in response to devil declines