Urban forest fragments as unexpected sanctuaries for the rare endemic ghost butterfly from the Atlantic forest

Abstract

Anthropogenic land expansion, particularly urbanization, is pervasive, dramatically modifies the environment and is a major threat to wildlife with its associated environmental stressors. Urban remnant vegetation can help mitigate these impacts and could be vital for species unable to survive in harsh urban environments. Although resembling nonurban habitats, urban vegetation remnants are subject to additional environmental stresses. Here, we evaluate the occurrence and density of the endemic ghost butterfly (Morpho epistrophus nikolajewna) that was once common, in the highly fragmented Atlantic forest of NE Brazil. We tested whether this butterfly would be found at lower densities in urban forest fragments of contrasting sizes as opposed to rural ones, given the number of environmental stressors found in urban areas. We surveyed 14 forest fragments (range 2.8 to over 3,000 ha) of semideciduous Atlantic forest in rural and urban locations using transect based distance sampling. The ghost butterflies showed strong seasonality; flying only from April to June. They were only identified in an urban fragment (515 ha), with an estimate of 720 individuals and a density 1.4 ind/ha. All forest fragments had experienced some level of logging in the past, which might have had an effect in the butterfly population. Nevertheless, rural forest fragments were subject to increased particulate matter concentrations, associated to biomass burning that we suggest might have had a more influential role driving the collapse of rural populations. Our findings show the importance of urban forest remnants to sustain population of this endangered species.

Cities as sanctuaries

“…2018; de Andrade et al . 2019). Mechanisms driving positive population growth in cities for both plants and animals include release from predators and human overexploitation, increased resources (food and water subsidies, horticultural activities), release from competition, reduced chemical inputs (relative to agricultural land uses), higher temperatures and longer growing seasons, and higher prey abundance (Spotswood et al .…”

“…For example, fragments of Atlantic Forest in cities in northeastern Brazil are home to rare ghost butterflies ( Morpho epistrophus nikolajewna ), a species no longer found in similar rural forest patches (de Andrade et al . 2019). Similarly, in the Hawaiian Islands, anchialine pools occur primarily in developed areas (Figure 4a), and the metropolitan region of Melbourne, Australia, contains 87 reserves established specifically to protect the critically endangered Natural Temperate Grasslands of the Victorian Volcanic Plain (Figure 4b; Kendal et al .…”

“…For instance, breeding densities of the burrowing owl (Athene cunicularia), a grassland specialist, were higher in urban grasslands than in neighboring rural grasslands, due to owl preference for and selection of predator-free nesting sites in the city (Rebolo-Ifrán et al 2017). Likewise, populations of two globally threatened species of parrots in the Dominican Republic were higher in cities than in natural and rural habitats, likely as a result of overexploitation and illegal wildlife trade in rural areas (Luna et al 2018;de Andrade et al 2019). Mechanisms driving positive population growth in cities for both plants and animals include release from predators and human overexploitation, increased resources (food and water subsidies, horticultural activities), release from competition, reduced chemical inputs (relative to agricultural land uses), higher temperatures and longer growing seasons, and higher prey abundance (Spotswood et al 2021).…”