Biology subjects

Ascensao, F.

Publications and source records attributed to Ascensao, F..

3 recordsLinked to original sources

bioRxiv2022

Assessing the impact of roadkill on the persistence of wildlife populations: a case study on the giant anteater

Human activity is depleting biodiversity, and road networks are directly contributing to this trend due to roadkill. Nevertheless, few studies empirically estimated the impact of roadkill on wildlife populations. We integrated information on roadkill rates, population abundance, and animal movement to estimate the survival rates and the proportion of the population likely to be extirpated due to roadkill, using giant anteater (Myrmecophaga tridactyla) as model species. We then assessed the consequent implications of roadkill on population persistence using population viability analysis (PVA). The yearly survival rate of resident anteaters inhabiting road vicinity areas (0.78; CI:0.62-0.97) was considerably lower than for those living far from roads (0.95; CI:0.86-1.00). The real number of anteaters being road-killed is considerably higher than the one recorded in previous studies (by a factor of 2.4), with ca. 20% of the population inhabiting road vicinity areas being road-killed every year. According to PVA results, roadkill can greatly affect the persistence of the giant anteater populations by reducing the growth rate down to null or negative values. This study confirms that roads have significant impacts on local population persistence. Such impacts are likely to be common to other large mammals, calling for effective mitigation to reduce roadkill rates.

ecology↗

bioRxiv2022

Road encroachment mediates species occupancy, trait filtering and dissimilarity of songbird communities

Assessing the road effects on biodiversity is challenging because impacts may depend on both wildlife responses to roads and on the spatial arrangement of roads. We questioned whether an increase in road encroachment i.e., the advancement of roads into non-urban areas, leads to significant changes (positive and negative) in species occurrence, and if so, whether those changes are linked to specific traits related to perturbation sensitiveness, therefore acting as filters that increase the community compositional dissimilarity. Using a large citizen-science dataset of point-counts performed throughout Iberian Peninsula (4,459 unique survey sites), we modelled the effect of road density on the occurrence of common songbirds (n=58), while accounting for potential confounding effects of environment and survey effort. We then tested if species occurrence patterns would be linked to specific traits related to the ability to cope with human presence. Finally, we assessed how road density affect the community compositional dissimilarity. We estimated 24 (41%) and 12 (21%) species to be negatively and positively affected by roads, respectively. Increased road encroachment was positively related with a higher prevalence of urban dwellers and negatively related with the occurrence of species nesting and foraging on the ground. Furthermore, increasing road density translated into an increasing community compositional dissimilarity, mostly due to species turnover. Our study support previous research showing that roads have different effects on the occurrence of different species, but we revealed that at least three species' traits have a clear relation with such road responses. Such trait filtering is probably causing a high species turnover between songbird communities occurring in roaded and nearby roadless areas. Overall, we found that different species-specific responses to roads translates into changes at the community level. Landscape and road-network management should be conceived acknowledging that roads are contributing to biodiversity changes. As so, building upon the concepts of Land Sharing / Land Sparing, conservation actions should be tailored according to the different species responses e.g., road verge management targeting species having a positive relation with road density; and compensation actions targeting species showing a negative response toward roads.

ecology↗

bioRxiv2021

Roads as ecological traps for giant anteaters

Wildlife-vehicle collisions (WVC) represent a serious source of mortality for many species, threatening local populations persistence while also carrying a high economic and human safety cost. Animals may adapt their behaviour to road associated threats, but roadside resources can act as attractants, providing misleading signals about the quality of roadside habitats, ultimately acting as an ecological trap. Yet, the extent to which individuals modify their behaviour and space use to roads is largely unknown for most taxa. Using fine-scale movement data from 41 giant anteaters (Myrmecophaga tridactyla), tracked in the Brazilian Cerrado, we aimed to identify facets of movement behaviour that might exhibit plasticity to roads and traffic volume. Specifically, the analysis of daily and instantaneous movement speeds, home range characteristics, and crossing rates/times, allowed us to test for an effect of road proximity, traffic volume and natural linear features on movement behaviour. We found no effect of road proximity or traffic volume on space use or movement behaviour. While individuals tended to reduce their movement speed when approaching roads and crossed roads ~3 times less than would have been expected by random chance, none of the highways we monitored were impervious. The majority of tracked anteaters living near roads (<2km) crossed them, with higher crossing rates for males. Consequently, habitat near roads may function as an ecological trap where healthy individuals occupy the territories nearby or bisected by roads but eventually are road-killed given their regular crossings, leaving the territory vacant for subsequent occupation. Crucially, we found no evidence that anteaters actively searched for passage structures to cross the roads. This suggests that crossing structures alone are unlikely to mitigate WVC induced mortality. Our research reinforces the need to implement fencing, properly linked to existing passages, and minimising the amount of night-time driving to reduce the number of WVCs. Article Impact StatementAnalyses of giant anteater movement show how roads act as ecological traps, reinforcing the need for fencing and reduced night-time driving.

ecology↗