Read article from and briefly summarize it in your own words. Components from th

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Read article from and briefly summarize it in your own words. Components from the paper for summary: The direct observations or knowledge from published literature that motivated the present study. The question(s), or the goals/aims of the study posed by the researchers. The hypothesis tested. The predicted outcome of the test (if explicitly stated, or your predictions). The results of the study. Reference the paper. If there are no predictions given, make your own reasonable predictions for the study.

Special Issue Article: Tropical Insectivores Increased abundance, but reduced nest predation in the chestnut-backed antbird in costa rican rainforest fragments: surprising impacts of a pervasive snake species CrossMark Deborah M. Visco*, Thomas W. Sherry Dept. of Ecology & Evolutionary Biology, Tulane University, Boggs 400, New Orleans, LA 70118-6340, USA ARTICLE INFO ABSTRACT Article history: Received 1 April 2014 Received in revised form 8 January 2015 Accepted 17 January 2015 Available online 11 February 2015 Keywords: Birds Costa Rica Fragmentation La Selva Biological Station Myrmeciza exsul Nest predation Predators Pseustes Understory insectivorous birds often disappear from fragmented tropical rainforest landscapes before mechanisms such as increased rate of nest depredation can be evaluated. Here, we took advantage of chestnut-backed antbird (Myrmeciza exsul), a representative rainforest understory insectivore that per- sists in fragments (unlike many other understory species), to identify variables influencing nest predation rate and to test the hypothesis that nest predation underlies avian extirpation in tropical fragments. We compared nest predation rates, bird density, and predator identities in three habitats of lowland Carib- bean Costa Rica: two fragments, a peninsular reserve (La Selva Biological Station), and unfragmented rainforest. Our results suggest an inversely density-dependent nest predation pattern: In fragments, chestnut-backed antbirds reached their highest density and-contrary to predictions-experienced their lowest nest predation rates; La Selva on the other hand experienced the lowest density and highest pre- dation rate. Because nest predation decreased with fragmentation, it appears not to explain declines of understory insectivores from forest fragments generally. Nest survival models indicated that habitat best explained nest predation likelihood, whereas edge, annual, and nest age effects were unimportant. Video surveillance documented both bird-eating snake (Pseustes poecilonotus) causing 80% of nest loss overall (37 of 46 nests) and a larger variety of predators in fragments; thus, landscape factors influenced an understory bird's nest predation. Given the large effect on our focal species, Pseustes likely affects other understory nesters, a topic warranting further study. Tropical reserve conservation plans should consider potential impacts of specialized nest predators on vulnerable understory birds. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Mechanisms affecting bird populations in fragmented land- scapes typically reduce survival or reproduction. Nest predation Animal extirpation in fragmented tropical forest landscapes is is one such mechanism that may limit avian populations non-random; patterns of guild decline and loss following fragmen- (Newton, 2003; Ricklefs, 1969) and has long been suspected as a tation are often predictable (Bierregaard and Lovejoy, 1989; Ferraz factor threatening bird populations in temperate (Heske et al., et al., 2007). Larger animals, for example, tend to disappear first 2001) and tropical forest fragments (Oniki, 1979). However, it is from fragments due to the bushmeat trade (Duffy, 2003). Another generally difficult to generalize about nest predation over broad highly vulnerable group includes understory insectivorous birds scales, among birds with different nest structures, or even among and ant-following birds (ekerciolu et al., 2002; Sigel et al., similar species (Brawn et al., 2011). Whereas some studies find rel- 2006; Stouffer and Bierregaard, 1995; Stratford and Stouffer, atively high nest predation for tropical birds (Robinson et al., 1999). Whereas patterns of sensitivity have been identified, we 2000), others—especially at higher elevations—find rates similar still lack demographic or ecological explanations for most avian to those in temperate forests (Martin, 1996; Skutch, 1985). A responses to tropical forest fragmentation or other global change potential influence on nest predation that remains understudied phenomena, hampering conservation efforts (Robinson and in the tropics is density dependence (but see Boyle, 2008). Dense Sherry, 2012). territories can increase predators' ability to find the more clo- sely-spaced nests (Martin, 1988; McKellar et al., 2014; Page * Corresponding author. Tel.: +1 516 521 8317. et al., 1983). Yet bird density and nest predation are not always E-mail addresses: visco.deb@gmail.com (D.M. Visco), tsherry@tulane.edu positively correlated, and multiple life-history traits and contexts (T.W. Sherry). are relevant (Ricklefs, 2000; Schmidt and Whelan, 1999).

Explanation / Answer

Hypothesis: nest predation primary avian destroy in tropical fragment. nest predator differ spatially, and interfere the daily influence rate (DPR) was relatively sustained. Scientist contrast rate of nest predation, bird density, also predator similarities in three habitats of lowland Caribbean Costa Rica: two fragments, a peninsular reserve (La Selva Biological Station), and unfragmented rainforest. Results shows an inversely density-dependent nest predation pattern: In fragments, chestnut-backed antbirds extended their peak density and opposite to predictions accomplished their lowest rate of nest predation; On the other side La Selva accomplished the less density and large predation rate. Due to reduced nest predation with fragmentation, it emerge not to elaborate decrease of understory insectivores from forest fragments specifically. Models of nest survival shows that habitat best explained likelihood of nest predation, whereas edge, annual, and nest age effects were not essential. Video investigation described both bird-eating snake (Pseustes poecilonotus) resulting 80% of overall nest loss(37 of 46 nests) also a major diversity of predators in fragments; thus, landscape factors affect an understory nest predation of bird. Given the large effect on our focal species, Pseustes likely influence other understory nesters, a topic guarentee further study. Tropical reserve conservation plans should examine potential effects of exceptional nest predators on vulnerable understory birds.

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