Identifying the possibilities and pitfalls of conducting IUCN Red List assessments from remotely sensed habitat information based on insights from poorly known Cuban mammals

The International Union for Conservation of Nature's Red List of Threatened Species (RLS) is the key global tool for objective, repeatable assessment of species’ extinction risk status, and plays an essential role in tracking biodiversity loss and guiding conservation action. Satellite remote sensing (SRS) data sets on global ecosystem distributions and functioning show exciting potential for informing range-based RLS assessment, but their incorporation has been restricted by low temporal resolution and coverage of data sets, lack of incorporation of degradation-driven habitat loss, and noninclusion of assumptions related to identification of changing habitat distributions for taxa with varying habitat dependency and ecologies. For poorly known mangrove-associated Cuban hutias (Mesocapromys spp.), we tested the impact of possible assumptions regarding these issues on range-based RLS assessment outcomes. Specifically, we used annual (1985–2018) Landsat data and land-cover classification and habitat degradation analyses across different internal time series slices to simulate range-based RLS assessments for our case study taxa to explore potential assessment uncertainty arising from temporal SRS data set coverage, incorporating proxies of (change in) habitat quality, and assumptions on spatial scaling of habitat extent for RLS parameter generation. We found extensive variation in simulated species-specific range-based RLS assessments, and this variation was mostly associated with the time series over which parameters were estimated. However, results of some species-specific assessments differed by up to 3 categories (near threatened to critically endangered) within the same time series, due to the effects of incorporating habitat quality and the spatial scaling used in RLS parameter estimation. Our results showed that a one-size-fits-all approach to incorporating SRS information in RLS assessment is inappropriate, and we urge caution in conducting range-based assessments with SRS for species for which habitat dependence on specific ecosystem types is incompletely understood. We propose novel revisions to parameter spatial scaling guidelines to improve integration of existing time series data on ecosystem change into the RLS assessment process.     

Unexpected consequences of vertebrate pest control: predictions from a four-species community model.

Although indirect effects are important structuring forces in ecological communities, they are seldom considered in the design of pest control operations. However, such effects may cause unpredicted and deleterious changes in other populations that could reduce or even negate the benefit to endangered species for which control is undertaken. Furthermore, the complexity and nonlinearities inherent in interacting ecological communities may cause thresholds in the strength of pest control, on either side of which indirect effects could vary greatly in their magnitude and desirability. We constructed a four-species simulation model for a common pest community in New Zealand beech (Nothofagus spp.) forests: house mice, ship rats, stoats, and brushtail possums. When the model was perturbed to simulate common control techniques, marked increases in the abundance of nontarget pest species were observed at the next forest mast. Higher mouse numbers were observed following both toxin (1080) application and rat kill-trapping, and higher rat numbers were observed following stoat kill-trapping, due to a release from predation in all cases. In comparison, a marked decrease in stoat abundance at the next forest mast was observed following simultaneous control of rats and mice, due to the effects of decreased prey abundance on the stoat population. For rat control, the size of the indirect effect on mouse numbers increased monotonically with control strength. Because the curvature of the relationship is slight, the relationship between the direct benefits of control and the indirect costs incurred would remain relatively unchanged regardless of the strength of control employed. For simultaneous mouse and rat control, however, high levels of control (as initially simulated) were predicted to cause decreased peak stoat abundance at the next mast event, whereas intermediate and low levels of control were predicted to cause increased stoat abundance. Hence, this study demonstrates two points of concern for pest managers. First, indirect effects of control operations do have the potential to reduce the planned-for benefit. Second, thresholds in the strength of control employed can potentially occur, across which indirect effects switch from being of conservation benefit to being of conservation concern.     

Environmental Contaminants in Blood, Hair, and Tissues of Ocelots from the Lower Rio Grande Valley, Texas, 1986–1997

The ocelot (Felis pardalis) isan endangered neotropical cat distributed within asmall range in the Lower Rio Grande Valley (LRGV), inTexas, U.S.A. Studies of the impacts of environmentalcontaminants in wild cats are few. Approximately onefourth of the estimated population (about 100) ofocelots in the LRGV was sampled to evaluate theimpacts of chlorinated pesticides, polychlorinatedbiphenyls, and trace elements on the population. Hairwas collected from 32 ocelots trapped between 1986–1992,and blood was collected from 20 ocelots trappedbetween 1993–1997. A few blood samples were obtainedfrom individuals recaptured two or three times. Tissue samples from 4 road-killed ocelots were alsoanalyzed. DDE, PCBs, and Hg were some of the mostcommon contaminants detected in hair and blood. MeanHg levels in hair ranged from 0.5 to 1.25 g g^-1 dw,Se from 1.5 to 3.48 g g^-1 dw, and Pb from 0.56 to26.8 g g^-1 dw. Mean DDE concentrations in plasma ranged from 0.005 g g^-1 ww to 0.153 g g^-1 ww, and PCBs ranged from 0.006 g g^-1 ww to 0.092 g g^-1 ww. Mean Hg levels in red blood cells rangedfrom 0.056 g g^-1 dw to 0.25 g g^-1 dw. Concentrations of DDE, PCBs, or Hg, did not increasesignificantly with age, although the highestconcentrations of DDE and Hg were found in olderanimals. Overall, concentrations of DDE, PCBs, and Hgwere low and at levels that currently do not pose anythreat to health or survival of the ocelot. This isfurther supported by good reproduction of the ocelotin the LRGV, where adult females averaged about 1.5kittens/litter. Thus, it seems that the current majorthreat to recovery of the ocelot in the LRGV may behabitat loss, although potential impacts of newgeneration pesticides, such as organophosphorus andcarbamate insecticides need further study.     

The Five Freedoms of Animal Welfare are Rights

In this paper I defend a theory of welfare rights for nonhuman animals. I do this by demonstrating that a well-established framework for protecting the interests of farm animals, the ‘Five Freedoms of Animal Welfare’, is already functioning just as a set of rights. To support this claim I adopt a common approach to detecting evidence for deontological reasoning and look at the structural features of rights. I first consider Hohfeld’s system of legal rights and consider whether the Five Freedoms may be understood as liberties or claim rights, before making a more successful comparison with side constraints and an interest theory of rights as understood by Nozick and Raz. I also respond to a likely objection that it is not possible to have some welfare rights without a right to freedom from exploitation. The argument therefore contributes to breaking down the stubborn division between ‘animal welfare’ and ‘animal rights’.     

A practical guide to avoid giving up on giving-up densities

The giving-up density (GUD) framework provides a powerful experimental approach with a strong theoretical underpinning to quantify foraging outcomes in heterogeneous landscapes. Since its inception, the GUD approach has been applied successfully to a vast range of foraging species and foraging scenarios. However, its application is not simple, as anyone who has tried to use it for the first time might attest. Limitations of the technique were noted at its conception, yet only the artificiality of the patches, the appropriateness of the food resource, and the possibility of multiple visiting foragers were identified. Here we show the current uses of GUD and outline the practical benefits as well as the often overlooked limitations of the technique. We define seven major points that need to be addressed when applying this methodology: (1) the curvilinearity between harvest rate and energy, (2) the energetic state of the forager, (3) the effect of group foraging, (4) food quality and substrate properties, (5) the predictability of the patch, (6) behavioral traits of the forager, and (7) nontarget species. We also suggest how GUD experiments can be enhanced by incorporating complementary methods (such as cameras) to better understand the foraging processes involved in the GUD itself. We conclude that the benefits of using GUD outweigh the costs, but that its limitations should not be ignored. Incorporating new methods when using GUD can potentially offer novel and important insights into the study of foraging behavior.     

Spatial scale of the patchiness of plant poisons: a critical influence on foraging efficiency

Generalist mammalian browsers and folivores feed on a range of chemically different plant species, which may assist them in diluting toxins and diversifying nutrient consumption. The frequency and order in which their diets are mixed are important determinants of intake. As a result, the degree of plant heterogeneity in an environment, and the spatial scale at which this occurs, should directly influence herbivore foraging decisions. We tested whether altering the Spatial scale of plants, and thus plant secondary metabolites (PSMs), affected foraging efficiency of a generalist folivore, the common brushtail possum (Trichosurus vulpecula). First, we demonstrated that possums were able to consume more from a mixed diet of two chemically different species, Eucalyptus globulus and E. tenuiramis, than when either of these species was offered alone. We then tested whether altering the spatial scale between E. globulus and E. tenuiramis, as small- or large-scale plant heterogeneity "patches," affected possum foraging behavior and, ultimately, their foraging efficiency. Possums increased their foraging efficiency when the spatial scale of plant heterogeneity was small rather than large. We argue that the ability to regularly switch diets, when plant spatial distribution is at a small scale, reduces the negative effects of PSM ingestion. We predict that the heterogeneity of plant patches, in relation to PSM distribution, and the scale at which this occurs across a landscape, are critical factors that influence foraging efficiency and, ultimately, fitness of mammalian herbivores. This research provides a fundamental link between plant chemistry, foraging, and habitat heterogeneity.     

Ancient manuring practices pollute arable soils at the St Kilda World Heritage Site, Scottish North Atlantic

The impact of ancient fertilization practices on the biogeochemistry of arable soils on the remote Scottish island of Hirta, St Kilda was investigated. The island was relatively unusual in that the inhabitants exploited seabird colonies for food, enabling high population densities to be sustained on a limited, and naturally poor, soil resource. A few other Scottish islands, the Faeroes and some Icelandic Islands, had similar cultural dependence on seabirds. Fertilization with human and animal waste streams (mainly peat ash and bird carcases) on Hirta over millennia has led to over-deepened, nutrient-rich soils (plaggen). This project set out to examine if this high rate of fertilization had adversely impacted the soil, and if so, to determine which waste streams were responsible. Arable soils were considerably elevated in Pb and Zn compared to non-arable soils. Using Pb isotope signatures and analysis of the waste streams, it was determined that this pollution came from peat and turf ash (Pb and Zn) and from bird carcases (Zn). This was also confirmed by ¹³C and ¹⁵N analysis of the profiles which showed that soil organic matter was highly enriched in marine-derived C and N compared to non-arable soils. The pollution of such a remote island may be typical of other ‘bird culture’ islands, and peat ash contamination of marginal arable soils at high latitudes may be widespread in terms of geographical area, but less intense at specific locations due to lower population densities than on Hirta.     

Environmentally adjusted productivity measurement: an Australian case study

This paper critically examines various methods for estimating productivity incorporating environmental effects for the Australian agricultural sector. The agricultural sector has been selected because of its strategic position in the economy of Australia. The findings of this study indicate that the application of environmentally adjusted productivity methods is a credible approach to measure productivity, in the context of sustainable development. Although the empirical findings of this research are case study specific, the results provide evidence supporting the adoption of these techniques to other sectors of the economy when measuring productivity and needing to be cognisant of sustainable development. The findings suggest that adjusting for the environmental impacts of soil erosion can result in higher or lower agricultural productivity depending on the assumptions we make regarding damage costs of erosion. It is argued in this paper that, for soil erosion in Australia, assumptions yielding higher productivity (i.e., upwardly adjusted) are justified. Finally, the findings of this study and the use of the methods presented point to important gaps in data availability. This gap needs to be addressed by policy makers if sustainable development objectives are to be credibly assessed using these techniques.