Field margins as ecological corridors: Uncovering connectivity in agricultural landscapes using high-resolution tracking data and translocation experiments

Ecological corridors are key for reducing habitat fragmentation, yet their
designation often relies on structural connectivity analysis based on
expert opinion, land uses, and species occurrence rather than actual
movement analysis, limiting our understanding of their effectiveness. This
study aims to explore and experimentally test how different habitats
facilitate or impede species movement in an intensive agricultural
landscape designated as ecological corridors. Using a cutting-edge
tracking system (ATLAS), we monitored the movement of 68 white-spectacled
bulbuls (Pycnonotus xanthopygos) at high resolution (4 or 8-second
intervals) and explored fine-scale habitat selection through integrated
step selection analysis, focusing on movement segments while excluding
static periods. To validate our observational findings, we conducted a
translocation experiment with 64 bulbuls across three habitat treatments:
natural, arable fields, and arable fields intersected by a main paved
road. We compared return time, number of stops, the movement straightness
of return flights across treatments, and the habitat selection during
these flights. Bulbuls avoided arable fields, which significantly impeded
their movement through the agricultural landscape. This was further
confirmed in the translocation experiment, where bulbuls from the
'arable field' treatment took the longest to return, made the
most stops, and followed the most tortuous paths.  Bulbuls
demonstrated a strong preference for vegetative features, such as narrow
field-margins, which comprised only 2.2% of the study area, underscoring
their importance as movement corridors. The translocation experiment
reinforced this result, with bulbuls consistently selecting field-margins
regardless of their treatment group. Additionally, bulbuls from the
‘natural’ treatment returned the fastest and followed the most direct
paths.  Synthesis and applications: Our study demonstrates that
field-margins can play a major role in maintaining connectivity and
enhancing ecological corridor functionality in intensive agriculture
landscapes, even for habitat generalist species like the bulbul. The use
of high-resolution movement data enabled fine-scale habitat analysis,
revealing the key role of these vegetative features in facilitating
movement. Conservation efforts should prioritize maintaining these
small-scale elements to enhance corridor effectiveness in agricultural
landscapes.