Gap-crossing by Wood Thrushes (Hylocichla mustelina)in a fragmented landscape

2011 ◽  
Vol 89 (11) ◽  
pp. 1091-1097 ◽  
Author(s):  
T. MacIntosh ◽  
B.J.M. Stutchbury ◽  
M.L. Evans
Keyword(s):  
Radio Telemetry ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Forest Fragment ◽  
Hylocichla Mustelina ◽  
Continuous Forest ◽  
Migratory Songbirds ◽  
Gap Crossing ◽  
Wood Thrushes ◽  
Gap Width

We used radio-telemetry to study the movement patterns of Wood Thrushes ( Hylocichla mustelina (J.F. Gmelin, 1789)) occupying small forest fragments (<5 ha) to examine gap-crossing between fragments and edge use within fragments. We found that 82% (8/11) of males and 33% (2/6) of females made at least one foray off of its resident forest fragment and we documented a total of 26 off-fragment forays (n = 79 h tracking). Males spent, on average, 23.5% of their time off their fragment, while females were gone 12.8% of the time tracked. Most forays were >150 m in distance and foray rate to adjacent fragments declined with increasing gap width. Males on fragments spent more time off their territory (23.5%) and traveled farther (392 m) than males occupying territories within a continuous forest (4.8% and 99 m, respectively). In fragments, 10 out of 17 individuals spent >80% of their time within 20 m of the fragment edge and edge use was significantly more than expected based on the amount of edge available in each fragment. This study adds to the growing evidence for migratory songbirds that during the breeding season, forest fragmentation may increase rather than impede daily movements.

scholarly journals Sexual Differences in Gap-Crossing Ability of a Forest Songbird in a Fragmented Landscape Revealed Through Radiotracking

The Auk ◽  
2002 ◽  
Vol 119 (2) ◽  
pp. 528-532 ◽  
Author(s):  
D. Ryan Norris ◽  
Bridget J. M. Stutchbury
Keyword(s):  
Breeding Season ◽  
Radio Telemetry ◽  
Sexual Differences ◽  
Fragmented Landscape ◽  
Fragmented Habitat ◽  
Wilsonia Citrina ◽  
Continuous Forest ◽  
Gap Crossing ◽  
Hooded Warblers ◽  
Extrapair Copulation

Abstract We used radio telemetry to examine extraterritorial movements of female Hooded Warblers (Wilsonia citrina) breeding in small, isolated woodlots. Only 44% of the nine females tracked left their woodlots (n = 6 forays in total). Compared to males followed in the same fragments (Norris and Stutchbury 2001), females spent significantly less time off territory and traveled shorter distances across nonforested gaps. Unlike males in fragmented habitat and females in continuous forest, we found no evidence that females were actively seeking extrapair copulations. We conclude females are relatively more restricted to isolated fragments during the breeding season and suggest that the lack of extrapair copulation opportunity could contribute to female avoidance of fragmented habitat, resulting in a high number of unmated males. This study emphasizes the importance of examining the potential effects of fragmentation in both sexes.

scholarly journals Distribution of Atta (Hymenoptera - Formicidae) in "terra-firme" rain forest of Central Amazonia: density, species composition and preliminary results on effects of forest fragmentation

1988 ◽  
Vol 18 (3-4) ◽  
pp. 309-315 ◽  
Author(s):  
Heraldo Luís de Vasconcelos
Keyword(s):  
Species Composition ◽  
Rain Forest ◽  
Abundant Species ◽  
Forest Fragments ◽  
Forest Fragment ◽  
Terra Firme ◽  
Atta Sexdens ◽  
Conservation Areas ◽  
Continuous Forest ◽  
Leaf Cutting

One hundred and fourteen hectares of a "terra-fiirme" rain forest 70 km north of Manaus, Amazonas, Brazil, were surveyed for leaf-cutting ant colonies (Atta spp). One half of this area was in isolated forest fragments (surrounded by pastures or second growth) of two sizes: 1 and 10 ha. The other half was in non-isolated fragments (connected to a large parch of forest) of the same sizes. Only two species occured in this forest: Atta sexdens sexdens L. and A. cepfhalotes L. The first was the most abundant species with a mean density of 0.35 colonies per ha. The mean density of A. cephalotes colonies was 0.03 per ha. The density of colonies was not significantly different between the isolated fragments and the continuous forest. Furthermore, the species composition did not change with isolation. However, pre-isolation data and long term monitoring are necessary to conclude that the isolation of a forest fragment has no effect upon Atta colonies. The non-uniform spatial distribution of Atta colonics within the "terra-firme" forest must be taken into account when selecting conservation areas in the Amazon, in order to preserve this important group of ants together with their native habitat.

scholarly journals Impacts of Housing Developments on Wood Thrush Nesting Success in Hardwood Forest Fragments

The Condor ◽  
2005 ◽  
Vol 107 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Judith Phillips ◽  
Erica Nol ◽  
Dawn Burke ◽  
Wendy Dunford
Keyword(s):  
Nest Predation ◽  
Molothrus Ater ◽  
Forest Edge ◽  
Forest Fragments ◽  
Hylocichla Mustelina ◽  
Wood Thrush ◽  
Housing Developments ◽  
Las Casas ◽  
Wood Thrushes ◽  
Small Forest

Abstract We studied the impacts of low density, exurban housing developments on Wood Thrushes (Hylocichla mustelina) breeding in small forest fragments in two regions of rural southern Ontario. In both regions, Wood Thrushes breeding in woodlots with embedded houses (housing penetrating the forest border) experienced significantly higher rates of parasitism by Brown-headed Cowbirds (Molothrus ater) than Wood Thrushes breeding in woodlots with adjacent houses (houses within 100 m of the forest edge), or undeveloped woodlots (no houses within 100 m of the forest edge). Wood Thrushes breeding in Peterborough area woodlots with embedded or adjacent houses experienced significantly increased rates of nest predation compared to Wood Thrushes breeding in undeveloped woodlots. This increased nest predation resulted in significant reductions in seasonal productivity in developed woodlots. No increase in nest predation was experienced by Wood Thrushes nesting in developed woodlots in the Ottawa region. The effects of housing developments appear to be region-specific and may depend on other factors influencing the overall abundance of cowbirds. Impactos de la Construcción de Viviendas en el Éxito de Nidificación de Hylocichla mustelina en Fragmentos de Bosque Resumen. Estudiamos los impactos de la construcción en baja densidad de viviendas peri-urbanas sobre individuos de Hylocichla mustelina que se encontraron criando en fragmentos pequeños de bosque en dos regiones rurales del sur de Ontario. En ambas regiones, los individuos de H. mustelina que se reprodujeron en bosques donde había casas inmersas (que penetraban el borde del bosque) experimentaron tasas de parasitismo por Molothrus ater significativamente mayores que los individuos criando en bosques con casas adyacentes (dispuestas a menos de 100 m del borde del bosque), o en bosques no alterados por la presencia de casas (a más de 100 m del borde del bosque). Los individuos de H. mustelina que se encontraron criando en áreas boscosas de Peterborough, donde las casas estaban adentro o adyacentes al bosque, experimentaron incrementos significativos en las tasas de depredación de nidos comparados con individuos que criaron en bosques no alterados. Este incremento en la depredación de nidos llevó a reducciones significativas en la productividad estacional en los bosques con viviendas. No registramos un incremento en la depredación de nidos de H. mustelina en bosques con viviendas en la región de Ottawa. Los efectos de la construcción de viviendas parecen estar relacionados de modo específico con la región y podrían depender de otros factores que influencian la abundancia de M. ater.

scholarly journals Species richness and relative abundance of birds in natural and anthropogenic fragments of Brazilian Atlantic forest

2004 ◽  
Vol 76 (2) ◽  
pp. 429-434 ◽  
Author(s):  
Luiz dos Anjos
Keyword(s):  
Species Richness ◽  
Atlantic Forest ◽  
Relative Abundance ◽  
Feeding Habits ◽  
Species Number ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Forest Fragment ◽  
Forest Patches ◽  
Forest Remnants

Bird communities were studied in two types of fragmented habitat of Atlantic forest in the State of Paraná, southern Brazil; one consisted of forest fragments that were created as a result of human activities (forest remnants), the other consisted of a set of naturally occurring forest fragments (forest patches). Using quantitative data obtained by the point counts method in 3 forest patches and 3 forest remnants during one year, species richness and relative abundance were compared in those habitats, considering species groups according to their general feeding habits. Insectivores, omnivores, and frugivores presented similar general tendencies in both habitats (decrease of species number with decreasing size and increasing isolation of forest fragment). However, these tendencies were different, when considering the relative abundance data: the trunk insectivores presented the highest value in the smallest patch while the lowest relative abundance was in the smallest remnant. In the naturally fragmented landscape, time permitted that the loss of some species of trunk insectivores be compensated for the increase in abundance of other species. In contrast, the remnants essentially represented newly formed islands that are not yet at equilibrium and where future species losses would make them similar to the patches.

scholarly journals Delayed effects of climate on vital rates lead to demographic divergence in Amazonian forest fragments

2021 ◽  
Author(s):  
Eric R Scott ◽  
Emilio Miguel Bruna ◽  
María Uriarte
Keyword(s):  
Amazon Basin ◽  
Life History Stage ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Vital Rates ◽  
Climate Data ◽  
Plant Populations ◽  
Delayed Effects ◽  
Continuous Forest ◽  
Flowering Probability

Deforestation often results in landscapes where remaining forest habitat is highly fragmented, with remnants of different sizes embedded in an often highly contrasting matrix. Local extinction of species from individual fragments is common, but the demographic mechanisms underlying these extinctions are poorly understood. It is often hypothesized that altered environmental conditions in fragments drive declines in reproduction, recruitment, or survivorship. The Amazon basin, in addition to experiencing continuing fragmentation, is warming and experiencing changes in precipitation leading to altered frequency and intensity of droughts and unusually wet periods. Whether plant populations in tropical forest fragments are particularly susceptible to extremes in precipitation remains unclear. Most studies of plants in fragments are relatively short (1-6 years), focus on a single life-history stage, and often do not compare to populations in continuous forest. Even fewer studies consider delayed effects of climate on demographic vital rates despite the importance of delayed effects in studies that consider them. Using a decade of demographic and climate data from an experimentally fragmented landscape in the Central Amazon, we assess the effects of climate on populations of an understory herb (Heliconia acuminata, Heliconiaceae). We used distributed lag non-linear models to understand the delayed effects of temperature and precipitation on survival, growth, and flowering. We detected delayed effects of climate up to 36 months. Drought two dry seasons prior to the February census decreased survival and increased flowering probability while drought in the wet season a year prior to the census decreased flowering probability and increased growth. The effects of extremes in precipitation on survival and growth were more pronounced in forest fragments compared to continuous forest. The complex delayed effects of climate and habitat fragmentation in our study point to the importance of long-term demography experiments in understanding the effects of anthropogenic change on plant populations.

scholarly journals Effects of Forest Fragmentation on the Vertical Stratification of Neotropical Bats

Diversity ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 67 ◽  
Author(s):  
Inês Silva ◽  
Ricardo Rocha ◽  
Adrià López-Baucells ◽  
Fábio Z. Farneda ◽  
Christoph F. J. Meyer
Keyword(s):  
Forest Fragmentation ◽  
Vertical Structure ◽  
Three Dimensional ◽  
Vertical Stratification ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Continuous Forest ◽  
Forest Strata ◽  
Neotropical Bats ◽  
Artibeus Lituratus

Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional forest space, studies are biased towards understory-based surveys and only few assessments of vertical stratification were done in fragmented landscapes. Using both ground and canopy mist-nets, we investigated how the vertical structure of bat assemblages is influenced by forest fragmentation in the experimentally fragmented landscape of the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Over a three year-period, we captured 3077 individuals of 46 species in continuous forest (CF) and in 1, 10 and 100 ha forest fragments. In both CF and forest fragments, the upper forest strata sustained more diverse bat assemblages than the equivalent understory layer, and the midstory layers had significantly higher bat abundance in fragments than in CF. Artibeus lituratus and Rhinophylla pumilio exhibited significant shifts in their vertical stratification patterns between CF and fragments (e.g., R. pumilio was more associated with the upper strata in fragments than in CF). Altogether, our study suggests that fragmentation modulates the vertical stratification of bat assemblages.

scholarly journals Small mammal glucocorticoid concentrations vary with forest fragment size, trap type, and mammal taxa in the Interior Atlantic Forest

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sarah A. Boyle ◽  
Noé U. de la Sancha ◽  
Pastor Pérez ◽  
David Kabelik
Keyword(s):  
Atlantic Forest ◽  
Small Mammals ◽  
Acute Stress ◽  
Physiological Stress ◽  
Fragment Size ◽  
Hair Shaft ◽  
Forest Fragments ◽  
Forest Fragment ◽  
Trapping Methods ◽  
Free Ranging

AbstractSpecies that live in degraded habitats often show signs of physiological stress. Glucocorticoid hormones (e.g., corticosterone and cortisol) are often assessed as a proxy of the extent of physiological stress an animal has experienced. Our goal was to quantify glucocorticoids in free-ranging small mammals in fragments of Interior Atlantic Forest. We extracted glucocorticoids from fur samples of 106 small mammals (rodent genera Akodon and Oligoryzomys, and marsupial genera Gracilinanus and Marmosa) from six forest fragments (2–1200 ha) in the Reserva Natural Tapytá, Caazapá Department, Paraguay. To our knowledge, this is the first publication of corticosterone and cortisol levels for three of the four sampled genera (Akodon, Oligoryzomys, and Marmosa) in this forest system. We discovered three notable results. First, as predicted, glucocorticoid levels were higher in individuals living withing small forest fragments. Second, animals captured live using restraint trapping methods (Sherman traps) had higher glucocorticoid levels than those animals captured using kill traps (Victor traps), suggesting that hair glucocorticoid measures can reflect acute stress levels in addition to long-term glucocorticoid incorporation. These acute levels are likely due to urinary steroids diffusing into the hair shaft. This finding raises a concern about the use of certain trapping techniques in association with fur hormone analysis. Finally, as expected, we also detected genus-specific differences in glucocorticoid levels, as well as cortisol/corticosterone ratios.

scholarly journals The persistence of ant-following birds in small amazonian forest fragments

1989 ◽  
Vol 19 (0) ◽  
pp. 249-263 ◽  
Author(s):  
Lee H. Harper
Keyword(s):  
Forest Fragments ◽  
Ant Colonies ◽  
Amazonian Forest ◽  
Army Ant ◽  
Continuous Forest ◽  
Introduced Birds ◽  
Small Forest

SUMMARYMist-net captures of army ant-following bird were monitored during the isolation of central Amazonian forest fragments of 1 ha (n = 5), 10 ha (n = 4) and 100 ha (n = 1). Post-isolation captures of the three obligate ant-following birds Dendrocinela merula, Pithys albifrons, and Gymnopithys rufigula decreased significantly in all fragments. post-isolation captures of four facultative ant-following species were not significantly different in forest fragments of 1 ha and 10 ha, although two species decreased significantly in the 100 ha fragment. Experimental introductions of obligate species into small forest fragments in the absence and presence of introduced Eciton burchelli army ant colonies resulted in significantly greater recaptures of introduced birds when active army ant colonies were present. Of the 105 birds introduced, 58 ' 55%) crossed 100-320 m od dedorested area an were recaptured in continuous forest.

scholarly journals Arboreal aperitifs: Space use and activity of a major songbird nest predator in a tropical Thailand forest

2021 ◽  
Author(s):  
Anji D’souza ◽  
George Gale ◽  
Benjamin Michael Marshall ◽  
Daphawan Khamcha ◽  
Surachit Waengsothorn ◽  
...  
Keyword(s):  
Brownian Bridge ◽  
Radio Telemetry ◽  
Space Use ◽  
Evergreen Forest ◽  
Boiga Irregularis ◽  
Forest Fragment ◽  
Predator Species ◽  
Avian Nest ◽  
Nest Predator ◽  
Nesting Season

ABSTRACTPredator-prey interactions are fundamental drivers of population dynamics, yet rarely are both predator and prey species simultaneously studied. Despite being significant, widespread avian nest predators, research on the ecology of Southeast Asian snakes in relation to birds remains scarce. The green cat snake (Boiga cyanea) is a primary nest predator, responsible for ≈24% of forest songbird depredation in Northeast Thailand. We explored both diurnal and nocturnal movements of 14 (5 male, 9 female) adult B. cyanea with radio-telemetry for an average of 68 ± 16 days per individual, between 21 October 2017 and 8 June 2019 in the dry evergreen forest of the Sakaerat Biosphere Reserve (SBR). We quantified area of space use (ha) and activity through motion variance (Ϭm2) during the study period using dynamic Brownian bridge movement models, and linked our findings to a simultaneously-run avian nest monitoring study, initiated in 2013 within the same forest fragment. On average, movements, space use and activity differed between males and females, and between the avian nesting and non-nesting seasons. Males moved 51.37 m/day farther than females. They used areas 15.09 ha larger than females, and their activity was 3.91 Ϭm2 higher than that of females. In general, individuals moved 50.30 m/day farther during the nesting season than the non-nesting season. The snakes used areas 9.84 ha larger during the nesting season than the non-nesting season, and their activity during the nesting season was 3.24 Ϭm2 higher than that during the non-nesting season. All individuals were exclusively nocturnal, moving throughout the night, and often descending from higher diurnal refugia (>2 m) to forage closer to the ground after sunset. Boiga cyanea activity followed a similar trend to that of the recorded nest depredations at SBR. Our study links snake activity to nest depredations in SBR. Our openly-available data may yield further insight when combined with other major avian nest predator species like the congeneric invasive brown tree snake (Boiga irregularis) on the island of Guam.

scholarly journals Recover and They’ll Come: Flower Visiting Bees Benefit from the Continuous of Micro-Environments Set by Regenerating Forest Fragments

Sociobiology ◽  
2021 ◽  
Vol 68 (1) ◽  
pp. 5861
Author(s):  
Ana Isabel Sobreiro ◽  
Lucas Lopes da Silveira Peres ◽  
Jessica Amaral Henrique ◽  
Rosilda Mara Mussury ◽  
Valter Vieira Alves-Junior
Keyword(s):  
Urban Areas ◽  
Environmental Changes ◽  
Climatic Conditions ◽  
Agricultural Activity ◽  
Forest Fragments ◽  
Forest Types ◽  
Continuous Forest ◽  
Flower Visiting ◽  
Bee Communities ◽  
Forest Habitats

Forest habitats are important sources of food and nesting resources for pollinators, primarily in urban areas and landscapes with intense agricultural activity. The forest fragmentation and environmental changes occurring in these green refuges are known to impose survival challenges to pollinating bees, leading to species loss. However, it is not well known how the species of bees that visit flowers are distributed in forest micro-environments. To fill this gap, we sampled flower visiting bees in a continuous forest matrix with micro-environments of two forest types (mature and regenerating forest). We examined how the local environmental changes and climatic conditions affect the composition and uniformity of bee communities in the different micro-environments. Our results indicated that both abundance and richness were similar between forest types studied here, however climatic conditions and plant flowering patterns affect the composition of bees. Thus, our results demonstrated that the continuous micro-environments can favor floral visits and the reintegration of bee communities, and still, that this strategy can be used to minimize the impacts of environmental changes at local scales.

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