Movement of Moths Through Riparian Reserves Within Oil Palm Plantations

Abstract

Tropical forests are becoming increasingly fragmented through conversion to agriculture, with negative consequences for biodiversity. Movement of individuals among the remaining fragments is critical to allow populations of forest-dependent taxa to persist. In SE Asia, conversion of forests to oil palm plantations is a particular threat. Many oil palm dominated landscapes retain forested riparian reserves along streams and rivers, but the extent to which these riparian reserves are used for movement, relative to the oil palm matrix, is poorly understood. We used mark-release-recapture methods to investigate the movement of five moth taxa in riparian reserves connected to a continuous forest area within oil palm matrix in Sabah, Malaysian Borneo. Moths were recaptured on average 68 m from the release point, and the mean time to recapture was between 2 and 3 days. Moths showed a significant tendency to move within forested riparian reserves than into adjacent oil palm. When moving within riparian reserves moths also showed a tendency to orient their movement away from the continuous forest into the riparian reserve rather than toward continuous forest or into oil palm. Overall, our results show a role for riparian reserves as movement corridors through oil palm plantations for some invertebrate species, strengthening the case for their retention and re-establishment.

Movement of forest‐dependent dung beetles through riparian buffers in Bornean oil palm plantations

“…Remaining forest patches within mosaic oil palm landscapes are often found in the form of strips of natural or restored vegetation by the side of waterways known as riparian buffers (also called riparian reserves or riparian strips; Luke et al, 2019). These riverine forest areas are primarily set aside to reduce run-off into streams (Sweeney et al, 2004) but can also improve water quality (Mayer et al, 2007) and benefit aquatic and forest-dependent terrestrial fauna (Gray et al, 2014(Gray et al, , 2019bMarczak et al, 2010;Ricketts, 2004). In addition, riparian buffers have the potential to serve as movement corridors between forest fragments and continuous forest (Beier & Noss, 1998;Tewksbury et al, 2002).…”

“…As forest patches within oil palm landscapes become increasingly fragmented and isolated, the persistence of species within forest patches may become critically dependent on the connectivity between fragments (Ewers & Didham, 2006;Hanski, 1999;Lucey & Hill, 2012). Therefore, understanding how animal species move through the landscape separating fragments has become a key consideration in conservation and management strategies for humanmodified landscapes (Doherty et al, 2021;Gray et al, 2019b).…”

“…These species typically have restricted ranges and are reluctant to cross forest boundaries, resulting in small, isolated populations which can suffer local extinctions with little prospect of recolonisation (Scriven et al, 2015;Sodhi et al, 2010). However, despite the importance of connectivity of fragments for conservation planning, relatively few studies have investigated the movement behaviour of tropical forest-associated taxa (Bouchard & Brooks, 2004;Brouwers & Newton, 2009;Gray et al, 2019b;Khazan, 2014;Lucey & Hill, 2012;Scriven et al, 2017).…”

“…We used mark-release-recapture (MRR) methods, a common technique for the study of insect movement (Gray et al, 2019b;Hanski, 1999;Lewis et al, 1997;Slade et al, 2013) and the newly developed Joint Species Movement Modelling approach (JSMM- Ovaskainen et al, 2019). JSMM allows both species-and communitylevel movement parameters to be estimated simultaneously.…”

Importance of Small Forest Fragments in Agricultural Landscapes for Maintaining Orangutan Metapopulations

“…These corridors are often set aside as high conservation value forests to meet sustainability certification criteria, either as riparian buffers or other linkages between forest patches. Retaining or creating forest corridors within oil palms will improve the permeability of the landscape for many species, in addition to orangutans (Gray et al, 2019;Scriven et al, 2019). The presence of resident adult females and their offspring in some of the isolated forest patches suggests that males are able to cross the human-modified landscape to search for receptive females and reproduce, but this hypothesis needs further investigation.…”