Wildlife is imperiled in peri-urban landscapes: threats to arboreal mammals

Abstract

Urbanization and deforestation impose severe challenges to wildlife, particularly for forest-living vertebrates. Understanding how the peri-urban matrix impacts their survival is critical for designing strategies to promote their conservation. We investigated the threats faced by brown howler monkeys (Alouatta guariba clamitans) in peri-urban regions of Rio Grande do Sul (RS) and Santa Catarina (SC) states, southern Brazil, by compiling conflicts reported over more than two decades. We assessed the major conflicts, their distribution among age-sex classes, and the predictors of conflict-related mortality using GLMMs. After 20+ years of monitoring, we compiled 540 conflicts (RS=248 and SC=292). Electrocution in power lines was the most frequent cause of death or injury (37%), followed by dog attack (34%), run over (17%), and human mistreatment (12%). The occurrence of lethal injuries ranged from 5% to 69% depending on the type of conflict and state. The overall post-conflict mortality was 56%. Adult males and females were the major victims in both states. The minimal adequate GLMM explained 83% of the variation in conflict-related mortality. State, conflict type, and age-sex class were the main predictors of mortality. Overall, mortality was lower in SC and after human mistreatment, and higher among adult females than in the other classes. We found that the survival of brown howlers in the forest-urban interface is constrained by both the urban infrastructure and the growing interactions with humans and domestic and stray dogs. We propose the placement of aerial bridges, road signs and speed bumps in areas of frequent animal crossing, the sterilization of stray dogs, and the sensitization of local inhabitants on the importance of respecting and protecting wildlife to reduce their conflicts with humans and domestic animals in the forest-urban interface.Graphical AbstractHIGHLIGHTSWe investigated the threats faced by brown howler monkeys in peri-urban regions of southern Brazil.After 20+ years of monitoring, we compiled 540 conflicts between monkeys and humans in the two study regions.The main conflicts were electrocution (37%), dog attack (34%), run over (17%), and mistreatment (12%).Lethal injuries ranged from 5% to 69% depending on conflict type.State, conflict type, and age-sex class explained 83% of the variation in conflict-related mortality.

Effects of a sprawling city in the viability of the black-horned capuchin

“…Management actions are being studied and implemented in several locations where primate populations are at risk in peri-urban zones. Some examples that can also be implemented in EERP are: the allocation of corridors, aerial bridges (Donaldson and Cunneyworth, 2015;Lindshield, 2016; NGO Kids Saving the Rainforest), and speed reducers to mitigate roadkill (Chaves et al, 2022); use of insulated cables to prevent electrocution (Chaves et al, 2022;Lindshield, 2016;Lokschin et al, 2007;Printes et al, 2010); sterilization of domestic and stray dogs to diminish their number and prevent attacks (Chaves et al, 2022;Lindshield, 2016;Oliveira et al, 2008) and environmental education and use of signs in sites where citizens are used to feeding the monkeys in order to discourage food supplementation in the long term, to keep the primates as wild as possible (Maibeche et al, 2015).…”

“…Further urbanization of EERP surroundings will probably increase threats faced by Sapajus nigritus population and then increase its mortality. A possible scenario may be similar to those of Alouatta guariba clamitans in urbanized areas in southern Brazil, where a long-term study suggested the main threats faced by these populations are electrocution, mistreatment, dog attacks, and roadkill (Chaves et al, 2022). So, we modeled the viability with a 2,5%, 5%, and 10% increase in mortality at all ages and sexes, except 0-1 year.…”

“…Even though primates are often considered intelligent and adaptable animals, 75% of all primate species are under population decline, mainly due to human activities (Estrada et al, 2017). Hence, primates around the world have been somehow affected by habitat loss due to city sprawl, either by specific urban threats (Chaves et al, 2022); changes in feeding behavior (Ilham et al, 2017;Maibeche et al, 2015); impacts in demographic traits, travel distances, home range size and foraging patterns (Hoffman and O'Riain, 2011); and increase in parasite load (Thatcher et al, 2021).…”