Carlos Fonseca

Habitat Split and the Global Decline of Amphibians

The worldwide decline in amphibians has been attributed to several causes, especially habitat loss and disease. We identified a further factor, namely “habitat split”—defined as human-induced disconnection between habitats used by different life history stages of a species—which forces forest-associated amphibians with aquatic larvae to make risky breeding migrations between suitable aquatic and terrestrial habitats. In the Brazilian Atlantic Forest, we found that habitat split negatively affects the richness of species with aquatic larvae but not the richness of species with terrestrial development (the latter can complete their life cycle inside forest remnants). This mechanism helps to explain why species with aquatic larvae have the highest incidence of population decline. These findings reinforce the need for the conservation and restoration of riparian vegetation.

A global meta‐analysis of the relative extent of intraspecific trait variation in plant communities

Recent studies have shown that accounting for intraspecific trait variation (ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25% of the total trait variation within communities and 32% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies.

Wild boar populations up, numbers of hunters down? A review of trends and implications for Europe.

Across Europe, wild boar numbers increased in the 1960s-1970s but stabilised in the 1980s; recent evidence suggests that the numbers and impact of wild boar has grown steadily since the 1980s. As hunting is the main cause of mortality for this species, we reviewed wild boar hunting bags and hunter population trends in 18 European countries from 1982 to 2012. Hunting statistics and numbers of hunters were used as indicators of animal numbers and hunting pressure. The results confirmed that wild boar increased consistently throughout Europe, while the number of hunters remained relatively stable or declined in most countries. We conclude that recreational hunting is insufficient to limit wild boar population growth and that the relative impact of hunting on wild boar mortality had decreased. Other factors, such as mild winters, reforestation, intensification of crop production, supplementary feeding and compensatory population responses of wild boar to hunting pressure might also explain population growth. As populations continue to grow, more human-wild boar conflicts are expected unless this trend is reversed. New interdisciplinary approaches are urgently required to mitigate human-wild boar conflicts, which are otherwise destined to grow further.

Habitat Split as a Cause of Local Population Declines of Amphibians with Aquatic Larvae

Most amphibian species have biphasic life histories and undergo an ontogenetic shift from aquatic to terrestrial habitats. In deforested landscapes, streams and forest fragments are frequently disjunct, jeopardizing the life cycle of forest-associated amphibians with aquatic larvae. We tested the impact of habitat split--defined as human-induced disconnection between habitats used by different life-history stages of a species--on four forest-associated amphibian species in a severely fragmented landscape of the Brazilian Atlantic Forest. We surveyed amphibians in forest fragments with and without streams (referred to as wet and dry fragments, respectively), including the adjacent grass-field matrix. Our comparison of capture rates in dry fragments and nearby streams in the matrix allowed us to evaluate the number of individuals that engaged in high-risk migrations through nonforested habitats. Adult amphibians moved from dry fragments to matrix streams at the beginning of the rainy season, reproduced, and returned at the end of the breeding period. Juveniles of the year moved to dry fragments along with adults. These risky reproductive migrations through nonforested habitats that expose individuals to dehydration, predation, and other hazards may cause population declines in dry fragments. Indeed, capture rates were significantly lower in dry fragments compared with wet fragments. Declining amphibians would strongly benefit from investments in the conservation and restoration of riparian vegetation and corridors linking breeding and nonbreeding areas.

The hard-tick fauna of mainland Portugal (Acari: Ixodidae): an update on geographical distribution and known associations with hosts and pathogens

This work is an updated revision of the available information on Portuguese ixodid tick species. It includes data on tick biology, ecology, taxonomy and host/pathogen-associations. The current list of Portuguese ixodid ticks comprises twenty species: Dermacentor marginatus (Sulzer, 1776), Dermacentor reticulatus (Fabricius, 1794), Haemaphysalis hispanica Gil Collado, 1938, Haemaphysalis inermis Birula, 1895, Haemaphysalis punctata Canestrini & Fanzago, 1878, Hyalomma lusitanicum Koch, 1844, Hyalomma marginatum Koch, 1844, Ixodes acuminatus Neumann, 1901, Ixodes bivari Dias, 1990, Ixodes canisuga Johnston, 1849, Ixodes frontalis (Panzer, 1798), Ixodes hexagonus Leach, 1815, Ixodes ricinus (Linnaeus, 1758), Ixodes simplex Neumann, 1906, Ixodes ventalloi Gil Collado, 1936, Ixodes vespertilionis Koch, 1844, Rhipicephalus (Boophilus) annulatus (Say, 1821), Rhipicephalus bursa Canestrini & Fanzago, 1878, Rhipicephalus pusillus Gil Collado, 1938, and Rhipicephalus sanguineus (Latreille, 1806).

Herbivory and the Long-Lived Leaves of an Amazonian Ant-Tree

1 Tachigali myrmecophila (Caesalpinaceae) is an Amazonian myrmecophytic canopy tree. The saplings are shade-tolerant, surviving in a suppressed state for several years in the rainforest understorey, the hollow leaf rachis and petiole being inhabited by the stinging ant Pseudomyrmex concolor (Pseudomyrmecinae). An experiment was designed (a) to evaluate the role of insect herbivory in the mutualism between T. myrmecophila and P. concolor and (b) to test a falsifiable hypothesis proposed by a current trade-off model of chemical and ant defences which predicts that myrmecophytic traits should be limited to plants with leaves of low longevity. 2 Plants from which the ants were experimentally removed had 4.3 times more herbivorous insects than plants with ants. All recorded orders of insects were attacked similarly by the ants. Rates of herbivory were: (a) ten times higher on experimental plants lacking ants, (b) about three times higher on immature than mature leaves, (c) about two and a half times higher in the wet than the dry season. After 18 months, the experimental plants presented an accumulated level of leaf herbivory which was about twice as high as for the plants with ants. 3 Observations on the phenology of control, experimental, and naturally unoccupied plants revealed that the leaf longevity of plants with active ant colonies was unexpectedly high for rainforest (81 months), and about 1.8 and 2.6 times as high as the experimental (45 months) and the naturally unoccupied (31 months) plants, respectively. The high leaf longevity of the myrmecophytic T. myrmecophila does not support the current trade-off model of chemical and ant defences. The rate of apical growth was 1.6 times higher for plants with ants than plants from the experimental group. The slow growth rate of T. myrmecophila, about 14 cm year-1, is compatible with the resource availability hypothesis. 4 Phenological differences between experimental and naturally unoccupied plants suggest that descriptive-correlative studies would not always give a true picture and that the actual paradigm of ant-plant interactions, derived in part from this approach, should be carefully revised. 5 The results corroborate the hypothesis that the interaction between Tachigali myrmecophila and Pseudomyrmex concolor is mutualistic, and suggest that attack by phytophagous insects is the prime factor in the evolution of the myrmecophytism.

The silent mass extinction of insect herbivores in biodiversity hotspots.

Habitat loss is silently leading numerous insects to extinction. Conservation efforts, however, have not been designed specifically to protect these organisms, despite their ecological and evolutionary significance. On the basis of species-host area equations, parameterized with data from the literature and interviews with botanical experts, I estimated the number of specialized plant-feeding insects (i.e., monophages) that live in 34 biodiversity hotspots and the number committed to extinction because of habitat loss. I estimated that 795,971-1,602,423 monophagous insect species live in biodiversity hotspots on 150,371 endemic plant species, which is 5.3-10.6 monophages per plant species. I calculated that 213,830-547,500 monophagous species are committed to extinction in biodiversity hotspots because of reduction of the geographic range size of their endemic hosts. I provided rankings of biodiversity hotspots on the basis of estimated richness of monophagous insects and on estimated number of extinctions of monophagous species. Extinction rates were predicted to be higher in biodiversity hotspots located along strong environmental gradients and on archipelagos, where high spatial turnover of monophagous species along the geographic distribution of their endemic plants is likely. The results strongly support the overall strategy of selecting priority conservation areas worldwide primarily on the basis of richness of endemic plants. To face the global decline of insect herbivores, one must expand the coverage of the network of protected areas and improve the richness of native plants on private lands.

Evaluation of Camera Trapping for Estimating Red Fox Abundance

Abstract The nature reserve Serra da Malcata, Portugal, was recently considered a site for Iberian lynx (Lynx pardinus) reintroduction. Because of potential disease risk posed by red foxes (Vulpes vulpes) in the area, a reliable estimate of fox abundance was critical for a dependable reintroduction program. We adapted camera-trapping techniques for estimating red fox abundance in the reserve. From July 2005 to August 2007, we conducted 7 camera-trapping sessions, allowing for individual identification of foxes by physical characteristics. We estimated abundance using the heterogeneity (Mh) model of the software program CAPTURE. Estimated density ranged from 0.91 ± 0.12 foxes/km2 to 0.74 ± 0.02 foxes/km2. By estimating red fox density, it is possible to define the number of foxes that must be sampled to assess the presence of potential fox-transmitted diseases that may affect lynx reintroduction.

Distribution, abundance and density of the wild boar on the Iberian Peninsula, based on the CORINE program and hunting statistics

Abstract. Wild boar population size in the Iberian Peninsula was estimated using hunting bag statistics from Spain and Portugal. Density was estimated assigning the wild boar population size to the “potential resources” or suitable habitats categorized by their importance to provide food and/or shelter to wild boars. Land uses were selected from CORINE, the EU database for land cover, using scientific literature and statistical significance for wild boar presence from published data. The hunting bag was 176245 and 15167 in Spain and Portugal, respectively. The average density was 0.373/km2 (min 0.014-max 2.22) in Spain and 0.13/km2 (min 0.00048-max 1.99) in Portugal, being 0.31/km2 (0.00048-2.22) over the entire Peninsula. Statistical analysis showed that wild boar presence was significantly (p < 0.05) associated to thirteen of the seventeen CORINE land uses selected. Agro-forestry, moors and heathland land use were not statistically significant but were included in the model due to their biological importance. Suitable habitats and distribution of wild boar were mapped for the Iberian Peninsula. This approach is a preliminary step intended to be useful in environmental management and animal health.

Comparative use of forest habitats by roe deer and moose in a human-modified landscape in southeastern Norway during winter

The negative impact of anthropogenic disturbance and land-use changes on large mammals is generally recognized within conservation biology. In southeastern Norway, both moose (Alces alces) and roe deer (Capreolus capreolus) occur throughout human-modified landscapes, facilitating an interesting comparative study of their habitat use. By using pellet group counts, we looked at the importance of forest structure, vegetation characteristics and human disturbance (e.g., distance to the nearest house, nearest paved road, and nearest edge between field and forest) in shaping the winter distribution of both species at multiple spatial scales, in non-agricultural habitats. Moose occurred more often in areas with higher densities of heather and Vaccinium sp. in the ground layer, and used areas with more open forest structure. The proportion of built-up areas, within a 1,000-m buffer, negatively influenced moose occurrence. Roe deer occurred more often in areas with deciduous trees and patches with juniper and Vaccinium sp. in the ground layer, used areas near roads less, but were significantly associated with areas near the field–forest ecotone. The proportion of built-up areas positively influenced roe deer distribution within a 2,500-m buffer. Roe deer seem to be able to persist in more human-dominated landscapes, possibly due to the availability of field–forest edges providing both high-quality fodder and cover in close proximity. Moose, on the contrary, did not show any preference for areas associated with human disturbance, and their distribution was only associated with patches providing food.