Effects of Forest Fragmentation on Central Amazonian Bird Demography

Avian diversity in degraded fragmented Amazonian landscapes depends on the persistence of species in cleared and disturbed areas. Regenerating forest facilitates bird dispersal within degraded Amazonian landscapes and may tip the balance in favor of persistence in previously depauperate habitat patches. Despite the potential value of Amazonian second growth, we lack comparisons of demography among second growth, continuous forest, forest fragments in regenerating landscapes, and truly isolated fragments. Here, we used point-count and capture data to compare Amazonian bird communities among continuous forest plots, 100 ha forest fragments with adjacent second growth, 100 ha forested islands bounded by water, young and older second growth plots. We also compared differences in survival, population growth and age ratios between primary and mature secondary forest. Among foraging guilds, understory insectivores and obligate-flocking species were nearly absent in islands and young second growth. Fragments surrounded by a regenerating matrix were surprisingly species rich, suggesting that a developing matrix may mitigate extinction associated with fragmentation. Survival and population growth was lower in mature second growth relative to primary forest for all foraging guilds except frugivores, gap specialists and ant-following birds. Similarly, age ratios were skewed towards more adult insectivorous birds in older forest; these findings suggest that dominant individuals may preferentially use older forest. Our findings reinforce that true islands are extinction-driven systems with distinct, depauperate communities. Islands are not appropriate comparisons to forest fragments in some landscapes. In contrast, succession of bird communities in second growth facilitates recolonization of forest fragments, permitting fragments as small as 100 ha to support bird communities similar to continuous forest

Integrating wildlife conservation into ecosystem service payments and carbon offsets: A case study from Costa Rica

Wildlife conservation is challenged by the expensive and cost prohibitive strategy of directly purchasing land to protect habitat at the landscape scale. An alternative mechanism used to protect habitat includes payments for ecosystem‐services (PES), where farmers and landowners are paid to manage their lands for a particular ecological service. Some of these easements are used to conserve a diversity of resources (i.e., water, soil, nutrient cycling, and biodiversity); however, the largest PES easement programs focus on carbon sequestration and are sold on international carbon markets as offsets. Here, we demonstrate that successfully protecting vulnerable habitat for wildlife can be achieved through partnerships with programs that trade in carbon offsets by focusing landowner recruitment activities in areas with ecologically valuable habitat. This collaborative strategy represents a cost effective and efficient model to protect wildlife at landscape scales. As proof of concept, in 2015 we successfully protected and restored habitats used by golden‐winged warblers, a species being considered by the United States Fish and Wildlife Service for protection under the Endangered Species Act, by partnering with organizations responsible for managing carbon offsets in Costa Rica. Through these partnerships, we successfully protected 790 ha of valuable habitat, within a single year, by recruiting farmers and landowners into an easement program in the heart of the warbler\u27s winter range. We present our efforts as a model for similar collaborative partnerships in the tropics and beyond

Habitat use of Nearctic-Neotropic migrant birds in northeastern Costa Rica

Many birds replenish energy reserves during semiannual migratory stopover periods in northeastern Costa Rica. Despite the importance of tropical staging areas to migrants, little research has focused on tropical stopover ecology. In this study, habitat use of 11 fall migrant species in northeastern Costa Rica were examined using bird banding data in association with a priori modeling methodologies. Frugivore capture rate and ripening of fruit peaked correspondingly in mid-October indicating a potential relationship between migrant arrival and the timing of ripe fruit availability. Top migrant habitat use models (encompassing a cumulative 95% AICc weight) contained fruit or arthropod abundance for 73% of the study species. Only Canada Warbler, Mourning Warbler and Eastern Wood-pewee, all insectivores, had top models that emphasized vegetative attributes without resource variables. Model results suggest that frugivorious migrants used fruit and insectivorous migrants used structure as cues for habitat use. Insectivores may have used habitat structure as a cue because of inherent difficulties associated with directly assessing arthropod availability.Thesis (M.S.)--Humboldt State University, Natural Resources: Wildlife, 200907/08.W.42.

Winter Territoriality of the American Redstart in Oil Palm Plantations

Aspects of territorial behavior of Nearctic-neotropical migratory birds during the nonbreeding period are poorly studied. Information about territoriality, site persistence, between-year site fidelity, and territory sizes are not available for most birds, especially in tropical agroecosystems. Given the rapid expansion of oil palm in the neotropics, determining how oil palm affects the territorial behaviors of overwintering migratory birds is an important line of inquiry with conservation implications. The American Redstart (Setophaga ruticilla) is considered a model species for the study of population dynamics in the neotropics; however, territory size for American Redstart has only been assessed in native habitats. In this study, we outfitted individual redstarts with radio tags, across two winter seasons, to determine variation in territory sizes across oil palm plantations and native forest patches in the State of Tabasco, Mexico. Average redstart territory size was 0.29 ha in oil palm plantations and 0.17 ha in native forest. Albeit presenting larger territories in oil palm plantations, which could indicate poorer habitat quality, the difference between both habitats was not statistically significant. Our results demonstrate, for the first time, that American Redstarts hold territories in oil palm plantations and that territory size may serve as an important indicator of relative habitat quality for redstart populations in tropical working landscapes

NDM-523: USE OF AN UNMANNED AERIAL VEHICLE (UAV) TO ASSESS TRANSPORTATION INFRASTRUCTURE, IMMEDIATELY AFTER A CATASTROPHIC STORM EVENT

From September 29 to October 1, 2015 over 200 mm of rain deluged parts of southern New Brunswick. The catastrophic rain event washed away bridge size culverts and conventional bridges, including the surrounding soil and asphaltic concrete pavement. Also erosion encroached on the driving lane of road and highway embankments at over 100 locations. Several homes and businesses were left stranded. A fast and efficient means was required to assess the impact on infrastructure after the storm. This paper presents the procedure and outcomes of using digital imagery captured with Unmanned Aerial Vehicles (UAVs) for post-disaster assessment. The use of a UAV to gather site images, at hard to access locations, allowed for the timely prioritization of needs and allocation of limited resources to areas most urgently in demand of emergency repairs. High quality aerial images were processed using commercial software specifically designed for the creation of 3D models and orthomosaics from aerial photos. This information, along with ground-level panoramas communicated the current condition of assets and roads. It provided engineers with the ability to complete initial assessment, create 3D models for design, and provide highly qualitative evaluation records. The successful use of a UAV for this storm event was preceded by other uses of UAVs for asset management within the New Brunswick Department of Transportation and Infrastructure

Factors affecting the distribution and abundance of autumn vagrant New World warblers in northwestern California and southern Oregon

Birds found outside their typical range, or vagrants, have fascinated naturalists for decades. Despite broad interest in vagrancy, few attempts have been made to statistically examine the explanatory variables potentially responsible for the phenomenon. In this study, we used multiple linear regression to model the occurrence of 28 rare warbler species (family Parulidae) in autumn in northern California and southern Oregon as a function of migration distance, continental population size, distance, and bearing to both closest breeding population and breeding population center. In addition to our predictive model, we used capture data from the California coast to 300 km inland to examine relationships between the presence of vagrant warblers, regional warbler species richness and age class distribution. Our study yielded three important results: (1) vagrancy is strongly correlated with larger North American population size; (2) vagrants are more common at some coastal sites; and (3) where young birds are over-represented, vagrants tend to occur—such as on the coast and at far inland sites. Of the many explanations of rare and vagrant individuals, we feel that the most likely is that these birds represent the ends of the distributions of a normal curve of migration direction, bringing some few migrants to locations out of their normal migratory range as vagrants. We also examine the underrepresented species that, according to our model, are overdue for being recorded in our study area

Effects of a regenerating matrix on the survival of birds in tropical forest fragments

Background Vast areas of lowland neotropical forest have regenerated after initially being cleared for agricultural purposes. The ecological value of regenerating second growth to forest-dwelling birds may largely depend on the age of the forest, associated vegetative structure, and when it is capable of sustaining avian demographics similar to those found in pristine forest. Methods To determine the influence of second growth age on bird demography, we estimated the annual survival of six central Amazonian bird species residing in pristine forest, a single 100 and a single 10 ha forest fragment, taking into consideration age of the surrounding matrix (i.e. regenerating forest adjacent to each fragment) as an explanatory variable. Results Study species exhibited three responses: arboreal, flocking and ant-following insectivores (Willisornis poecilinotus, Thamnomanes ardesiacus and Pithys albifrons) showed declines in survival associated with fragmentation followed by an increase in survival after 5 years of matrix regeneration. Conversely, Percnostola rufifrons, a gap-specialist, showed elevated survival in response to fragmentation followed by a decline after 5 years of regeneration. Lastly, facultative flocking and frugivore species (Glyphorynchus spirurus and Dixiphia pipra, respectively) showed no response to adjacent clearing and subsequent regeneration. Conclusions Our results in association with previous studies confirm that the value of regenerating forest surrounding habitat patches is dependent on two factors: ecological guild of the species in question and second growth age. Given the rapid increase in survival following succession, we suggest that the ecological value of young tropical forest should not be based solely on a contemporary snapshot, but rather, on the future value of mature second growth as well

Climate change aggravates bird mortality in pristine tropical forests

Stable understory microclimates within undisturbed rainforests are often considered refugia against climate change. However, this assumption contrasts with emerging evidence of Neotropical bird population declines in intact rainforests. We assessed the vulnerability of resident rainforest birds to climatic variability, focusing on dry season severity characterized by hotter temperatures and reduced rainfall. Analyzing 4264 individual bird captures over 27 years, we found that harsher Amazonian dry seasons significantly reduced apparent survival for 24 of 29 species, with longer-lived species being more strongly affected. Our model predicted that a 1°C increase in average dry season temperature would reduce the mean apparent survival of the understory bird community by 63%. These findings directly link climate change to declining bird survival in the Amazon, challenging the notion that pristine rainforests can fully protect their biodiversity under increasingly severe climate conditions

Using culturally significant birds to guide the timing of prescribed fires in the Klamath Siskiyou Bioregion

Historically, wildfire and tribal burning practices played important roles in shaping ecosystems throughout the Klamath Siskiyou Bioregion of northern California and southern Oregon. Over the past several decades, there has been increased interest in the application of fire for forest management through the implementation of prescribed fires within habitats that are used by a diversity of migrant and resident land birds. While many bird species may benefit from habitat enhancements associated with wildfires, cultural burning, and prescribed fire, individuals may face direct or indirect harm. In this study, we analyzed the timing of breeding and molting in 11 species of culturally significant land birds across five ecologically distinct regions of northern California and southern Oregon to explore the potential timeframes that these bird species may be vulnerable to wildland fires (wildfire, prescribed fire, or cultural burning). We estimated that these selected species adhered to a breeding season from April 21 to August 23 and a molting season from June 30 to October 7 based on bird capture data collected between 1992 and 2014. Within these date ranges, we found that breeding and molting seasons of resident and migratory bird species varied temporally and spatially throughout our study region. Given this variability, spring fires that occur prior to April 21 and fall fires that occur after October 7 may reduce the potential for direct and indirect negative impacts on these culturally significant birds across the region. This timing corresponds with some Indigenous ecocultural burning practices that are aligned with traditionally observed environmental cues relating to patterns of biological phenology, weather, and astronomy. We detail the timing of breeding and molting seasons more specific to regions and species, and estimate 75%, 50%, and 25% quartiles for each season to allow for greater flexibility in planning the timing of prescribed fires and cultural burning, or regarding the potential implications of wildfires. The results of our study may serve as an additional resource for tribal members and cultural practitioners (when examined within the context of Indigenous Traditional Ecological Knowledge) and forest and wildland fire managers to promote stable populations of culturally significant bird species within fire-dependent forest systems