Landscape-level effects on avifauna within tropical agriculture in the Western Ghats: Insights for management and conservation Jai Ranganathan a, * , Jagdish Krishnaswamy b , M.O. Anand c,d a National Center for Ecological Analysis and Synthesis, 735 State Street, Suite 300, Santa Barbara, CA 93101, USA b Ashoka Trust for Research in Ecology and the Environment, 659, 5th A Main, Hebbal, Bangalore 560024, India c National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road GKVK, Bangalore, Karnataka 560065, India d Nature Conservation Foundation, 3076/5, Fourth Cross, Gokulam Park, Mysore 570002, India article info Article history: Received 30 November 2009 Received in revised form 6 April 2010 Accepted 9 April 2010 Available online 30 June 2010 Keywords: Arecanut Betelnut Coffee Remote sensing Silver oak Greviella robusta Tasseled cap transformation Kauth–Thomas transformation abstract A critical handicap to tropical biodiversity conservation efforts in agroecosystems is the unknowns regarding the influence of landscape-scale factors on the persistence of species. To address these uncer- tainties, we explored two essential landscape-scale questions, within India’s biologically-rich Western Ghats, examining two nearby human-dominated landscapes that dramatically differed in their pattern of land cover. First, how does the proximity of intact forest patches affect bird community composition within agricultural landscapes? Second, can simple remote sensing-derived measures (brightness, wet- ness, and NDVI) be used to estimate native bird species composition within those landscapes? In both landscapes, as distance to intact forest decreased, the similarity in bird community composition between agricultural areas and intact forest increased. This suggests that the retention of tropical forest bird com- munities within human-dominated landscapes critically depends on the maintenance of nearby intact forest. In an answer to the second question, the remote sensing measures correlated with forest-affiliated avian species richness in only one of the two landscapes, reflecting an ecological difference between the two in the response of forest bird species to local agricultural conditions. In the landscape where a cor- relation was found, there was high variation in vegetative structure, which strongly impacted both the remote sensing measures and forest bird species richness. In the other landscape, forest species richness strongly correlated with changes in tree species composition in the agriculture, a factor that could not be detected by the remote sensing metrics. In order to successfully conserve biodiversity in tropical agricul- tural landscapes, our findings show that it is essential to conserve intact forest within those landscapes and to understand the effect of local agricultural practices on species. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction It has become apparent that the current biodiversity crisis will not be solved with protected areas alone, due to concerns of isola- tion, insufficient coverage, uncertain ecological performance, and likely vulnerability to large-scale human impacts like climate change (Rosenzweig, 2003; Gaston et al., 2008; Lee and Jetz, 2008). Consequently, much conservation attention has focused on lands outside of protected areas that form the vast majority of almost all landscapes, with recent findings strongly suggesting that species persistence depends largely on the quality of these unpro- tected lands (e.g. Debinski and Holt, 2000; Prugh et al., 2008). Hu- man pressures are rapidly intensifying on the native ecosystems that comprise these unprotected lands (Wackernagel et al., 2002), with agricultural expansion and intensification driving much of the ecosystem conversion and degradation (Jha et al., 2000; Barve et al., 2005; Foley et al., 2005; Kareiva et al., 2007). Be- cause agriculture so commonly displaces native ecosystems (Til- man et al., 2001), understanding the conditions under which agricultural landscapes can sustain native species is one of the most essential questions in conservation today (Sutherland et al., 2009). A frequent hallmark of agricultural landscapes is extremely complex mixtures of land covers (e.g. Estrada et al., 1994; Fischer et al., 2009), especially within areas that experience relatively low agricultural intensity (Vandermeer et al., 1998; Fischer et al., 2008). The standard landscape metrics and the standard methods of structuring landscape used in conservation sometimes do not capture the full complexity of agricultural landscapes (Franklin and Lindenmayer, 2009). The effect of this landscape complexity on species communities remains poorly understood (Turner, 2005). In fact, the unknowns surrounding the interactions between 0006-3207/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.biocon.2010.04.018 * Corresponding author. Tel.: +1 805 892 2134; fax: +1 805 892 2510. E-mail addresses: jai.ranganathan@gmail.com (J. Ranganathan), jagdish.krish- naswamy@gmail.com (J. Krishnaswamy). Biological Conservation 143 (2010) 2909–2917 Contents lists available at ScienceDirect Biological Conservation journal homepage: www.elsevier.com/locate/biocon