Agricultural fields structure affects landscape perception and movement decisions of understory birds

Habitat fragmentation in forest landscapes, often resulting from agricultural expansion, poses significant challenges to wildlife movement and persistence. The ability of forest-dependent species to traverse non-forested areas, such as sugarcane and Eucalyptus plantations (i.e. matrix), is crucial for maintaining population connectivity. This study investigates how matrix composition and gap distance influence the gap-crossing behavior of two understory bird species: the Variable Antshrike ( Thamnophilus caerulescens ) and the Sooty-fronted Spinetail ( Synallaxis frontalis ). We conducted playback experiments in ten sinuous forest fragments within the Brazilian Atlantic Forest, each surrounded by either sugarcane or Eucalyptus plantations. Birds were presented with two route options to reach the opposite edge: (1) a shorter path crossing the matrix or (2) a longer path along the forest edge. We hypothesized that: (a) birds would prefer routes within the forest edge over crossing the matrix; (b) the likelihood of gap crossing would decrease with increasing distance; and (c) Eucalyptus plantations would be more permeable than sugarcane. Edge-to-edge distances ranged from 30 to 130 meters. Control trials within continuous forest were also conducted for comparison. Results indicated a strong preference for forested routes ( T. caerulescens : 16% matrix crossings; S. frontalis : 10%). Additionally, a negative correlation was observed between gap distance and crossing probability, with longer distances deterring matrix crossings. Contrary to our expectations, sugarcane plantations exhibited higher permeability than Eucalyptus plantations. These findings highlight the importance of matrix composition in facilitating or impeding avian movement and emphasize its relevance for landscape-level conservation strategies.​