Inferring activity budgets in wild animals to estimate the consequences of disturbances

Activity budgets can provide a direct link to an animal's bioenergetic budget and is thus a valuable unit of measure when assessing human-induced nonlethal effects on wildlife conservation status. However, activity budget inference can be challenging for species that are difficult to observe and require multiple observational variables. Here, we assessed whether whalewatching boat interactions could affect the activity budgets of minke whales (Balaenoptera acutorostrata). We used a stepwise modeling approach to quantitatively record, identify, and assign activity states to continuous behavioral time series data, to estimate activity budgets. First, we used multiple behavioral variables, recorded from continuous visual observations of individual animals, to quantitatively identify and define behavioral types. Activity states were then assigned to each sampling unit, using a combination of hidden and observed states. Three activity states were identified: nonfeeding, foraging, and surface feeding (SF). From the resulting time series of activity states, transition probability matrices were estimated using first-order Markov chains. We then simulated time series of activity states, using Monte Carlo methods based on the transition probability matrices, to obtain activity budgets, accounting for heterogeneity in state duration. Whalewatching interactions reduced the time whales spend foraging and SF, potentially resulting in an overall decrease in energy intake of 42%. This modeling approach thus provides a means to link short-term behavioral changes resulting from human disturbance to potential long-term bioenergetic consequences in animals. It also provides an analytical framework applicable to other species when direct observations of activity states are not possible.

All the animals are gone? The politics of contemporary hunter arcade games.

Recent proliferation and popularity of personal computer and console games has meant that scholarship around video arcade games has been largely ignored. Arcade games had their halcyon days during the 1970s and 1980s when 'Space Invaders', 'Pong' and 'Donkey Kong' were household names. The inception of scholarship into games occurred in the 1990s; a time when arcade games were writ small in the cultural imagination, at least compared to the newer home computer and video games. Thus in games theory they are typically discussed only in terms of their role as antecedents to their more popular kin. Moreover, they seem innocuous because they are so publicly accessible. Against this assumption, and lack of scholarship, this paper explores a selection of contemporary arcade games which we describe as 'hunting' games. Arcade hunting games are first-person shooter (FPS) involving one or more players shooting simulated wild animals. They are commonly situated in cinema foyers, hotels, and family entertainment centres. However, despite a presumption of institutional moderation afforded by the public accessibility of these spaces, this paper argues that this genre works through a range of political modalities that require more scholarly consideration than currently given.

Total arsenic accumulation in yabbies (Cherax Destructor Clark) exposed to elevated arsenic levels in Victorian gold mining areas, Australia

Arsenic is a proven carcinogen often found at high concentrations in association with gold and other heavy metals. The freshwater yabby, Cherax destructor Clark (Decapoda, Parastacidae), is a ubiquitous species native to Australia's central and eastern regions, with a growing international commercial market. However, in this region of Australia, yabby farmers often harvest organisms from old mine tailings dams with elevated environmental arsenic levels. Yabbies exposed to elevated environmental arsenic were found to accumulate and store as much as 100 μg/g arsenic in their tissues. The accumulation is proportional to the concentration of arsenic in the sediment and is high enough to be of concern for people who eat the yabbies. A comparison of arsenic levels in wild and lab-fed animals also was performed. Although there was no significant difference in the level of arsenic in the various organs of the wild animals, the animals purchased from a yabby farm showed a significantly higher arsenic concentration in their hepatopancreas (3.7 ± 0.9 μg/g) compared to other organs (0.6–1.8 μg/g). Furthermore, after a 40-d exposure to food containing 200 to 300 μg/g inorganic arsenic, arsenate (As[V])-exposed animals showed a significant increase in tissue-specific arsenic accumulation, whereas arsenite (As[III])-exposed animals showed a lower, nonsignificant increase in As uptake, primarily in the hepatopancreas. These results have important implications for yabby growers and consumers alike.

The energetic and survival costs of growth in free-ranging chipmunks

The growth/survival trade-off is a fundamental aspect of life-history evolution that is often explained by the direct energetic requirement for growth that cannot be allocated into maintenance. However, there is currently no empirical consensus on whether fast-growing individuals have higher resting metabolic rates at thermoneutrality (RMRt) than slow growers. Moreover, the link between growth rate and daily energy expenditure (DEE) has never been tested in a wild endotherm. We assessed the energetic and survival costs of growth in juvenile eastern chipmunks (Tamias striatus) during a year of low food abundance by quantifying post-emergent growth rate (n = 88), RMRt (n = 66), DEE (n = 20), and overwinter survival. Both RMRt and DEE were significantly and positively related to growth rate. The effect size was stronger for DEE than RMRt, suggesting that the energy cost of growth in wild animals is more likely to be related to the maintenance of a higher foraging rate (included in DEE) than to tissue accretion (included in RMRt). Fast growers were significantly less likely to survive the following winter compared to slow growers. Juveniles with high or low RMRt were less likely to survive winter than juveniles with intermediate RMRt. In contrast, DEE was unrelated to survival. In addition, botfly parasitism simultaneously decreased growth rate and survival, suggesting that the energetic budget of juveniles was restricted by the simultaneous costs of growth and parasitism. Although the biology of the species (seed-storing hibernator) and the context of our study (constraining environmental conditions) were ideally combined to reveal a direct relationship between current use of energy and future availability, it remains unclear whether the energetic cost of growth was directly responsible for reduced survival.

The energetic and oxidative costs of reproduction in a free-ranging rodent

1. As understanding of the energetic costs of reproduction in birds and mammals continues to improve, oxidative stress is an increasingly cited example of a non-energetic cost of reproduction that may serve as a proximal physiological link underlying life-history trade-offs.

2. Here, we provide the first study to measure daily energy expenditure (DEE) and oxidative damage in a wild population. We measured both traits on eastern chipmunks (Tamias striatus) and assessed their relationships with age, reproductive status, litter size and environmental conditions.

3. We found that both physiological traits were correlated with environmental characteristics (e.g. temperature, seasons). DEE tended to increase with decreasing temperature, while oxidative damage was lower in spring, after a winter of torpor expression, than in autumn. We also found that DEE decreased with age, while oxidative damage was elevated in young individuals, reduced in animals of intermediate age and tended to increase at older age.

4. After controlling for age and environmental variables, we found that both female DEE and oxidative damage increased with litter size, although the latter increased weakly.

5. Our results corroborate findings from laboratory studies but highlight the importance of considering environmental conditions, age and reproductive status in broader analyses of the causes and consequences of physiological costs of reproduction in wild animals.

Indicators of the impact of climate change on migratory species

The Bonn Convention on the Conservation of Migratory Species of Wild Animals adopted a Resolution in 2005 recognising the impacts of climate change on migratory species. It called on Contracting Parties to undertake more research to improve our understanding of these impacts and to implement adaptation measures to reduce foreseeable adverse effects. Given the large diversity of taxa and species affected by climate change, it is impossible to monitor all species and effects thereof. However, it is likely that many of the key ecological and physical processes through which climate change may impact wildlife could be monitored using a suite of indicators, each comprising parameters of species/populations or groups of species as proxies for wider assemblages, habitats and ecosystems. Herein, we identify a suite of 17 indicators whose attributes could reveal negative impacts of climate change on the global status of migratory species: 4 for birds, 4 for marine mammals, 2 for sea turtles, 1 for fish, 3 for land mammals and 3 for bats. A few of these indicators would be relatively straightforward to develop, but most would require additional data collation, and in many cases methodological development. Choosing and developing indicators of the impacts of climate change on migratory species is a challenge, particularly with endangered species, which are subject to many other pressures. To identify and implement conservation measures for these species, indicators must account for the full ensemble of pressures, and link to a system of alerts and triggers for action.

Demographic and phenotypic effects of human mediated trophic subsidy on a large Australian lizard (Varanus varius): meal ticket or last supper?

Humans are increasingly subsidizing and altering natural food webs via changes to nutrient cycling and productivity. Where human trophic subsidies are concentrated and persistent within natural environments, their consumption could have complex consequences for wild animals through altering habitat preferences, phenotypes and fitness attributes that influence population dynamics. Human trophic subsidies conceptually create both costs and benefits for animals that receive increased calorific and altered nutritional inputs. Here, we evaluated the effects of a common terrestrial human trophic subsidies, human food refuse, on population and phenotypic (comprising morphological and physiological health indices) parameters of a large predatory lizard (∼2 m length), the lace monitor (Varanus varius), in southern Australia by comparison with individuals not receiving human trophic subsidies. At human trophic subsidies sites, lizards were significantly more abundant and their sex ratio highly male biased compared to control sites in natural forest. Human trophic subsidies recipient lizards were significantly longer, heavier and in much greater body condition. Blood parasites were significantly lower in human trophic subsidies lizards. Collectively, our results imply that human trophic subsidized sites were especially attractive to adult male lace monitors and had large phenotypic effects. However, we cannot rule out that the male-biased aggregations of large monitors at human trophic subsidized sites could lead to reductions in reproductive fitness, through mate competition and offspring survival, and through greater exposure of eggs and juveniles to predation. These possibilities could have negative population consequences. Aggregations of these large predators may also have flow on effects to surrounding food web dynamics through elevated predation levels. Given that flux of energy and nutrients into food webs is central to the regulation of populations and their communities, we advocate further studies of human trophic subsidies be undertaken to evaluate the potentially large ecological implications of this significant human environmental alteration.

Population, behavioural and physiological responses of an urban population of black swans to an intense annual noise event

Wild animals in urban environments are exposed to a broad range of human activities that have the potential to disturb their life history and behaviour. Wildlife responses to disturbance can range from emigration to modified behaviour, or elevated stress, but these responses are rarely evaluated in concert. We simultaneously examined population, behavioural and hormonal responses of an urban population of black swans Cygnus atratus before, during and after an annual disturbance event involving large crowds and intense noise, the Australian Formula One Grand Prix. Black swan population numbers were lowest one week before the event and rose gradually over the course of the study, peaking after the event, suggesting that the disturbance does not trigger mass emigration. We also found no difference in the proportion of time spent on key behaviours such as locomotion, foraging, resting or self-maintenance over the course of the study. However, basal and capture stress-induced corticosterone levels showed significant variation, consistent with a modest physiological response. Basal plasma corticosterone levels were highest before the event and decreased over the course of the study. Capture-induced stress levels peaked during the Grand Prix and then also declined over the remainder of the study. Our results suggest that even intensely noisy and apparently disruptive events may have relatively low measurable short-term impact on population numbers, behaviour or physiology in urban populations with apparently high tolerance to anthropogenic disturbance. Nevertheless, the potential long-term impact of such disturbance on reproductive success, individual fitness and population health will need to be carefully evaluated.

Drivers and fitness consequences of individual and sexual foraging specialisation in fur seals

What did you eat today? Yesterday? Do you think the person on your right had similar meals? Probably not! Similar variability exists in wild animals. During my PhD, I studied variation in feeding strategies among individuals of a same population, focusing on the main drivers and consequences in fur seals.

Assortative mating among animals of captive and wild origin following experimental conservation releases

Captive breeding is a high profile management tool used for conserving threatened species. However, the inevitable consequence of generations in captivity is broad scale and often-rapid phenotypic divergence between captive and wild individuals, through environmental differences and genetic processes. Although poorly understood, mate choice preference is one of the changes that may occur in captivity that could have important implications for the reintroduction success of captive-bred animals. We bred wild-caught house mice for three generations to examine mating patterns and reproductive outcomes when these animals were simultaneously released into multiple outdoor enclosures with wild conspecifics. At release, there were significant differences in phenotypic (e.g. body mass) and genetic measures (e.g. Gst and F) between captive-bred and wild adult mice. Furthermore, 83% of offspring produced post-release were of same source parentage, inferring pronounced assortative mating. Our findings suggest that captive breeding may affect mating preferences, with potentially adverse implications for the success of threatened species reintroduction programmes.

Spawning season, fecundity and proximate composition of the gonads of wild-caught blacklip abalone (Haliotis rubra) from Port Fairy waters, south eastern Australia

This study was based on wild-caught blacklip abalone Haliotis rubra L., from Port Fairy waters, south eastern Australia (142°15′E; 38°21′S), from July  1998 to November 1999, and was initiated to evaluate the spawning season and other aspects of its reproductive biology. The shell length and body weight of female and male abalone sampled ranged from 12.0 to 18.6 and 12 to 15 cm, and 137 to 529 and 148 to 585 g, respectively. The sex ratio did not vary significantly from 1:1 through the year. The gonadosomatic index (GSI) ranged from 3.0% to 8.4% in males, and 2.5% to 14.1% for females, and the highest GSI as well as the highest proportion of mature animals were recorded from September to October. During these months the hepatosomatic index (HSI) was low, and an inverse correlation between GSI and HSI (P < 0.05) was evident. Fecundity of blacklip abalone ranged from 1.09 to 7.5 million eggs for females of 12–14.5 cm in length, and 115–487 g in total body weight, respectively. The lipid content of the female gonad increased significantly from about July to November, and an opposite trend was observed for lipid content of the digestive gland. Seasonal changes in the protein and ash contents of the gonad and/or the digestive gland were not always significant.

Are most samples of animals systematically biased? Consistent individual trait differences bias samples despite random sampling

Sampling animals from the wild for study is something nearly every biologist has done, but despite our best efforts to obtain random samples of animals, ‘hidden’ trait biases may still exist. For example, consistent behavioral traits can affect trappability/catchability, independent of obvious factors such as size and gender, and these traits are often correlated with other repeatable physiological and/or life history traits. If so, systematic sampling bias may exist for any of these traits. The extent to which this is a problem, of course, depends on the magnitude of bias, which is presently unknown because the underlying trait distributions in populations are usually unknown, or unknowable. Indeed, our present knowledge about sampling bias comes from samples (not complete population censuses), which can possess bias to begin with. I had the unique opportunity to create naturalized populations of fish by seeding each of four small fishless lakes with equal densities of slow-, intermediate-, and fast-growing fish. Using sampling methods that are not size-selective, I observed that fast-growing fish were up to two-times more likely to be sampled than slower-growing fish. This indicates substantial and systematic bias with respect to an important life history trait (growth rate). If correlations between behavioral, physiological and life-history traits are as widespread as the literature suggests, then many animal samples may be systematically biased with respect to these traits (e.g., when collecting animals for laboratory use), and affect our inferences about population structure and abundance. I conclude with a discussion on ways to minimize sampling bias for particular physiological/behavioral/life-history types within animal populations.

Individual (co)variation in thermal reaction norms of standard and maximal metabolic rates in wild-caught slimy salamanders

Standard metabolic rate (SMR) and maximal metabolic rate (MMR) are fundamental measures in ecology and evolution because they set the scope within which animals can perform activities that directly affect fitness. In ectotherms, both SMR and MMR are repeatable over time when measured at a single ambient temperature (Ta). Many ectotherms encounter variable Ta from day to day and over their lifetime, yet it is currently unknown whether individual differences hold across an ecologically relevant range of Ta (i.e. thermal repeatability; RT). Moreover, it is possible that thermal sensitivity of SMR and MMR are important individual attributes, and correlated with one another, but virtually nothing is known about this at present. We measured SMR and MMR across an ecologically relevant Ta gradient (i.e. from 10 to 25 °C) in wild-caught salamanders (Plethodon albagula) and found that RT was significant in both traits. SMR and MMR were also positively correlated, resulting in a lower RT in absolute and factorial aerobic scopes (AAS and FAS). We found significant individual differences in thermal sensitivity for both SMR and MMR, but not for AAS and FAS. The intercept (at Ta = 0 °C) and the slope of the thermal reaction norms were negatively correlated; individuals with low MR at low Ta had a higher thermal sensitivity. Finally, individuals with a high thermal sensitivity for SMR also had high thermal sensitivity for MMR. Our results suggest that natural selection occurring over variable Ta may efficiently target the overall level of - and thermal sensitivity in - SMR and MMR. However, this may not be the case for metabolic scopes, as the positive correlation between SMR and MMR, in addition to their combined changes in response to Ta, yielded little individual variation in AAS and FAS. Our results support the idea that organisms with low metabolism at low Ta have a high metabolic thermal sensitivity as a compensatory mechanism to benefit in periods of warmer environmental conditions. Hence, our study reveals the importance of considering within-individual variation in metabolism, as it may represent additional sources of adaptive (co)variation.

Energy expenditure and personality in wild chipmunks

© 2015, Springer-Verlag Berlin Heidelberg. According to the “pace-of-life syndrome” concept, slow-fast life-history strategies favored under different ecological conditions should lead to co-adaptations between metabolic rate and personality traits such as activity, exploration, and boldness. Although the relationships between resting metabolic rate (RMR) and personality traits have been recently tested several times, we still do not know whether personality is related to the daily energy expenditure (DEE) of free-living individuals in their natural habitat. The objectives of this study were to assess the links between RMR, DEE, and two personality traits (exploration in an open-field and docility during handling) in wild eastern chipmunks (Tamias striatus). Using a multivariate mixed model, we found that exploration and docility were significantly correlated at the among-individual level, confirming the presence of a behavioral syndrome within our population. We also found that exploration, but not docility, was negatively correlated with DEE. Hence, fast explorers show lower DEE levels than slow explorers, independently of RMR and docility. This result adds to an increasingly large (and complex) literature reporting the impacts of personality traits on the biology, ecology, and physiology of animals in their natural environment.