Discriminating the Drivers of Edge Effects on Nest Predation: Forest Edges Reduce Capture Rates of Ship Rats (Rattus rattus), a Globally Invasive Nest Predator, by Altering Vegetation Structure

Nest predation risk often increases near forest edges in agricultural landscapes, but this pattern has rarely been found in forested landscapes. Whether this lack of relationship is general remains unclear, especially because no assessment of statistical power has been published. To (1) assess whether and how far nest predation risk is associated with forest edges and (2) avoid confounding effects of the surrounding landscape, we measured nest predator activity by placing baits at five distances (0, 30, 60, 90, and 120 m) from sharp, rectilinear forest edges that run along extensive tracts of forest. No association was found between distance to forest edges and bait discovery rates (P = 0.7). The lack of edge effect was unlikely to be caused by a lack of statistical power (1 - β > 0.8). However, bait discovery rates were significantly heterogeneous throughout the study area, and ground baits were taken at a greater rate than arboreal baits. Mice, voles, and red squirrels (Tamiasciurus hudsonicus (Erxleben)), all nest predators, were the main users of bait. Red squirrel occurrence, as estimated by playbacks, was higher in black spruce (Picea mariana (Mill.) BSP) than in balsam fir (Abies balsamea (L.) Mill.) stands but was not associated with a high bait predation rate. Our results strengthen support to the hypothesis that nests near open areas in managed boreal forests are not more at risk than forest-interior nests.

Download Full-text

Nest predation in Afrotropical forest fragments shaped by inverse edge effects, timing of nest initiation and vegetation structure

Journal of Ornithology ◽

10.1007/s10336-013-1021-9 ◽

2013 ◽

Vol 155 (2) ◽

pp. 411-420 ◽

Cited By ~ 11

Author(s):

Toon Spanhove ◽

Tom Callens ◽

Caspar A. Hallmann ◽

Petri Pellikka ◽

Luc Lens

Keyword(s):

Edge Effects ◽

Vegetation Structure ◽

Nest Predation ◽

Forest Fragments ◽

Nest Initiation

Download Full-text

Effects of habitat edges on vegetation structure and the vulnerable golden-brown mouse lemur (Microcebus ravelobensis) in northwestern Madagascar

BMC Ecology ◽

10.1186/s12898-020-00337-z ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Bertrand Andriatsitohaina ◽

Daniel Romero-Mujalli ◽

Malcolm S. Ramsay ◽

Frederik Kiene ◽

Solofonirina Rasoloharijaona ◽

...

Keyword(s):

Body Mass ◽

Edge Effects ◽

Vegetation Structure ◽

Species Abundance ◽

Tree Height ◽

Logistic Function ◽

Study Region ◽

Large Trees ◽

Significant Difference ◽

Vegetation Parameters

Abstract Background Edge effects can influence species composition and community structure as a result of changes in microenvironment and edaphic variables. We investigated effects of habitat edges on vegetation structure, abundance and body mass of one vulnerable Microcebus species in northwestern Madagascar. We trapped mouse lemurs along four 1000-m transects (total of 2424 trap nights) that ran perpendicular to the forest edge. We installed 16 pairs of 20 m2 vegetation plots along each transect and measured nine vegetation parameters. To determine the responses of the vegetation and animals to an increasing distance to the edge, we tested the fit of four alternative mathematical functions (linear, power, logistic and unimodal) to the data and derived the depth of edge influence (DEI) for all parameters. Results Logistic and unimodal functions best explained edge responses of vegetation parameters, and the logistic function performed best for abundance and body mass of M. ravelobensis. The DEI varied between 50 m (no. of seedlings, no. of liana, dbh of large trees [dbh ≥ 10 cm]) and 460 m (tree height of large trees) for the vegetation parameters, whereas it was 340 m for M. ravelobensis abundance and 390 m for body mass, corresponding best to the DEI of small tree [dbh < 10 cm] density (360 m). Small trees were significantly taller and the density of seedlings was higher in the interior than in the edge habitat. However, there was no significant difference in M. ravelobensis abundance and body mass between interior and edge habitats, suggesting that M. ravelobensis did not show a strong edge response in the study region. Finally, regression analyses revealed three negative (species abundance and three vegetation parameters) and two positive relationships (body mass and two vegetation parameters), suggesting an impact of vegetation structure on M. ravelobensis which may be partly independent of edge effects. Conclusions A comparison of our results with previous findings reveals that edge effects are variable in space in a small nocturnal primate from Madagascar. Such an ecological plasticity could be extremely relevant for mitigating species responses to habitat loss and anthropogenic disturbances.

Download Full-text

Urbanization Impacts on Mammals across Urban-Forest Edges and a Predictive Model of Edge Effects

PLoS ONE ◽

10.1371/journal.pone.0097036 ◽

2014 ◽

Vol 9 (5) ◽

pp. e97036 ◽

Cited By ~ 30

Author(s):

Nélida R. Villaseñor ◽

Don A. Driscoll ◽

Martín A. H. Escobar ◽

Philip Gibbons ◽

David B. Lindenmayer

Keyword(s):

Predictive Model ◽

Edge Effects ◽

Urban Forest ◽

Forest Edges

Download Full-text

Predation of artificial Xantus's murrelet (Synthliboramphus hypoleucus scrippsi) nests before and after black rat (Rattus rattus) eradication

Environmental Conservation ◽

10.1017/s0376892906002608 ◽

2005 ◽

Vol 32 (4) ◽

pp. 320-325 ◽

Cited By ~ 14

Author(s):

HOLLY P. JONES ◽

R. WILLIAMHENRY ◽

GREGG R. HOWALD ◽

BERNIE R. TERSHY ◽

DONALD A. CROLL

Keyword(s):

Nest Predation ◽

Life Stage ◽

Deer Mouse ◽

Rattus Rattus ◽

Small Population ◽

Eradication Programme ◽

Artificial Nests ◽

Black Rat ◽

Before And After ◽

Synthliboramphus Hypoleucus

Introduced rats depredate every life stage of island nesting seabirds, but the extent of predation is rarely quantified. Introduced black rat (Rattus rattus) and native deer mouse (Peromyscus maniculatus anacapae) predation on Xantus's murrelet (Synthliboramphus hypoleucus scrippsi) nests was experimentally quantified using artificial nests before and after rat eradication on Anacapa Island (California). The staged rat eradication programme provided experimental treatments: in 2002 rats were eradicated on one island (East Anacapa Islet) and remained on two islands (Middle and West Anacapa Islets), providing a control comparison, and, in 2003, rats were eradicated from the remaining islands (Middle and West Anacapa Islets). In 2002, 96% of artificial nests were depredated on control islands (rats present) with rats accounting for most predation. Nest predation on the treatment island (rats eradicated) in 2002 was significantly lower: 8% of artificial nests were depredated, mostly by endemic deer mice. In 2003, following rat eradication on the remaining islands (Middle and West Anacapa Islets), nest predation was reduced from 96% in 2002 to 3% of total nests in 2003. Predation of nests on East Anacapa Islet (rats eradicated in 2002) increased significantly due to reintroduction and recovery of native deer mouse populations, with 23% of artificial nests depredated. The inference is that rat predation on real Xantus's murrelet nests was responsible for the historically low nesting success and small population sizes of breeding murrelets on Anacapa Island. With rats removed, the hatching success of Xantus's murrelet chicks and the number of individuals nesting on Anacapa Island will increase dramatically. Artificial nest studies are particularly well suited to quantifying introduced rat impacts on hole and crevice nesting seabirds and can simultaneously serve as an effective monitoring tool to detect the presence of rats and the recovery of native nest predators.

Download Full-text

Vegetative and Fruit Resources as Determinants of Habitat use by Mature-Forest Birds During the Postbreeding Period

The Auk ◽

10.1093/auk/124.2.494 ◽

2007 ◽

Vol 124 (2) ◽

pp. 494-507 ◽

Cited By ~ 7

Author(s):

Andrew C. Vitz ◽

Amanda D. Rodewald

Keyword(s):

Vegetation Structure ◽

A Priori ◽

Forest Birds ◽

Canopy Height ◽

Theoretic Approach ◽

Mature Forest ◽

Risk Of Predation ◽

Structure Density ◽

Information Theoretic Approach ◽

Capture Rates

AbstractRecent studies have demonstrated that many birds of mature forests heavily use early-successional habitat during the postbreeding period. Two frequently invoked hypotheses to explain these shifts are that postbreeding birds select (1) dense cover to reduce risk of predation and (2) abundant fruit resources to facilitate foraging. Using mist nets between 15 June and 16 August in 2002 and 2003, we captured mature-forest birds during the postbreeding period in 12 regenerating hardwood clearcuts (three to seven years old) in southeast Ohio. Vegetation structure and fruit resources were measured at nine net locations within each clearcut. We applied an information-theoretic approach, where we used vegetative and fruit variables as predictors in seven a priori models to evaluate how habitat factors might explain capture rates. In two seasons, we captured 1,089 hatch-year (HY) and 445 after-hatch-year (AHY) postbreeding birds of 32 mature-forest species. In general, models reflecting habitat structure (density of low vegetation, canopy height) best explained variation in capture rates, which were negatively related to the density of low vegetation (<1.5 m) and positively related to canopy height. Extremely dense low vegetation may be disadvantageous if it inhibits movements and provides cryptic locations for ground predators. Instead, habitats with greater vertical structure (e.g., taller vegetation) and relatively less dense low vegetation below may provide better protection from aerial and ground predators. Overall, results suggest that vegetation structure may explain high use of early-successional forests by many birds during the postbreeding period, though fruit may be the most important factor for seasonal frugivores.Recursos Vegetativos y de Frutos como Determinantes del Uso de Hábitat por Aves de Bosque Maduro Durante el Período Posterior a la Reproducción

Download Full-text

Nest-predator prevalence along a mountain birch - alpine tundra ecotone

Wildlife Research ◽

10.1071/wr11031 ◽

2011 ◽

Vol 38 (6) ◽

pp. 525

Author(s):

Åshild Ø. Pedersen ◽

Lasse Asmyhr ◽

Hans Christian Pedersen ◽

Nina E. Eide

Keyword(s):

Nest Predation ◽

Alpine Tundra ◽

Mountain Birch ◽

Pine Marten ◽

Willow Ptarmigan ◽

Generalist Species ◽

Management Actions ◽

Nest Predator ◽

Predation Rates ◽

Birch Forests

Context Nest predation is a major factor influencing life history and population dynamics of ground-nesting birds. The transitions between the northern boreal mountain birch forests and the low-alpine tundra are important habitats for the willow ptarmigan, Lagopus lagopus (Linnaeus, 1758). During the past decades, these landscapes have been extensively developed with cabin resorts in southern Norway, which has led to an increased number of roads and foot paths in relatively undisturbed habitats. Aims The aim of the present study was to investigate relative nest-predation rates in elevation gradients (ecotones) spanning from northern boreal mountain birch forests to low-alpine tundra in three locations with contrasting willow ptarmigan densities. Methods We conducted an artificial nest study by using baited track boards (n = 108). Track boards were placed along transects (200 m) in the following three habitat types: birch forest, edge habitat and low-alpine tundra. Predator prevalence was analysed in relation to study-design variables (location, habitat, study period) and the load of human infrastructure (i.e. distance to foot paths and roads), using generalised linear mixed-effect models assuming binomial distribution for the response variable. Key results Prevalence of avian predators was consistently high (range 38.2–85.3%), in contrast to much lower prevalence of mammalian predators (range 2.8–22.9%). Raven (Corvus corax) was the dominant nest predator, followed by hooded crow (C. cornix) and pine marten (Martes martes). Location, as contrasted by differences in willow ptarmigan density, was not significantly related to total relative predation rates. Species-specific predator prevalence was habitat specific and related to human infrastructure, but with opposite relative predation patterns between pine marten and raven. Hooded crow predation was similar across the ecotone and not related to human infrastructure. Conclusions Predator prevalence was habitat specific and affected by human infrastructure (distance to human foot paths). Our study confirmed that human activity might alter the predation rates by generalist species in these low-alpine environments. Implications We recommend that attractive willow ptarmigan habitat should be avoided when planning human infrastructure in alpine ecosystems. To reduce predation pressure in this ecosystem, it appears that generalist predators should be considered for management actions. Further research is needed to explain the underlying mechanism driving expansion of generalist species into alpine habitats. Such knowledge is also important in developing alternative management actions with focus other than predator control.

Download Full-text