Until death do us part: abundance and survival of necrophagous beetle species associated with fox scats in fragmented landscapes

Abstract

Forestry companies have replaced and fragmented the native landscapes, generating a large number of unpaved roads, which can have a negative effect on non-flying invertebrates. Polynoncus bullatus is a common necrophagous beetle species depend on fox scats present on unpaved roads in fragmented landscapes in central Chile. Here, the effect of different habitat types (native forest, clear-cuts and unpaved roads) on the abundance of Lycalopex culpaeus scats as well as abundance and survival of P. bullatus in the fragmented landscape was evaluated. Scats and beetles were counted in seven independent fragments during 6 months and through sampling transects. Both responses and factors were associated with GLM, whereas survival was evaluated with a Kaplan-Meier test. Higher scats abundance was found on unpaved roads than other habitat types. Higher P. bullatus abundance was also significantly associated with unpaved roads than clear-cuts and native forest fragments. An additive model between habitat type and scat abundance was correlated with beetle abundance. Survival was significantly lower in unpaved roads, generating up to 42 % of beetles road-killed. Lycalopex culpaeus response positively to fragmentation defecating more on unpaved roads because foxes use it to move through the landscape. This fact attracts more P. bullatus individuals, being run-over by cars and trucks, representing an ecological trap for beetles. This interaction can be predictable and modeled for any period, length or road type avoiding potential massive road-kill events. Implications for insect conservation. Common and threatened invertebrate species are run-over when minor roads cross valuable natural or protected areas, evidencing the need of advance in road designs compatible with their conservation and mitigating negative impacts of forestry.