The Tucuman Parrot (Amazona tucumana), which is restricted to Southern Yungas forest of Argentina and Bolivia, ha not recovered from severe population declines in the 1980s. We assessed habitat conservation targets for this specie and asked, ‘‘What constitutes the right target?’’ For species with small ranges, maximizing the proportion of the rang under protection is an established strategy to safeguard against threats. However, designating an amount fo protection based on range alone (i.e. a ‘representation target’) may set a misguided conservation target if critica resources are not considered. We used an ensemble model (‘biomod2’) to map suitable breeding and nonbreedin habitat of the Tucuman Parrot based on environmental variables and key resources (breeding) or the species’occurrence (nonbreeding). Pino blanco (Podocarpus parlatorei) seeds are critical food for Tucuman Parrot nestlings, s we modeled the distribution of this tree as a proxy for potential breeding habitat. We then examined the adequacy o current habitat protection relative to representation targets and in light of known threats, including forest degradatio and loss, and poaching. Overall, 17% of the 110,122 km2 Southern Yungas is protected, which is close to th proportion recommended (the target; 22%), based on the ecoregion’s size, for inclusion in a conservation network Similarly, 26% of the 46,263 km2 of nonbreeding habitat is protected, also relatively successful at 71% of the targe (36%). However, of the scant ~21,000 km2 of breeding habitat, only 15% is protected, much less than th representation target (49%) recommended for maximizing the probability of population persistence. Poaching o nestlings further undermines the value of some nesting habitat in Bolivia. For Tucuman Parrots, increased enforcemen of protection in Bolivia and protection of additional nesting habitat in Argentina are the most efficient ways t enhance persistence. Our results illustrate how habitat conservation targets based on area alone may be inadequate i important biological information is overlooked.
File: Pidgeon et al. 2015_condor-14-214.pdf
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Extreme weather is becoming more pronounced, making phenological patterns les predictable. Among the potential consequences, extreme weather may alter relationships of migrator birds with their seasonal food resources and thus impact valuable ecosystem regulating services (e.g., bir predation of herbivorous insects). Our goal was to quantify the effect of an extremely warm spring on thes relationships in a U.S Midwest oak savanna. Average regional temperatures in the spring of 2009 couple with record highs in 2010 (88C warmer) were the basis of a natural experiment for addressing our goal. I both springs we documented tree flowering and leaf-out phenology, related these to arrival and foragin behavior of the three most abundant migratory wood-warbler species (Parulidae), and quantified the effect of migratory bird foraging on insect density, size, and herbivory using a branch exclosure experiment. I 2009, the dominant tree species at our study site, eastern black oak (Quercus velutina), flowered in mid-Ma and the wood warblers foraged heavily in the savanna during this time. Branches from which birds wer excluded exhibited a trend toward higher insect density, larger Lepidopterans, and greater flower damag than control branches. In 2010, tree phenology was four weeks earlier than in 2009 and the wood warbler were nearly absent from the savanna (83% fewer), likely because peak food availability preceded thei arrival in mid-May. Insect density was 83% greater in 2009 than 2010. However, in 2010, 81% of sample leaves exhibited substantial damage (.25% of leaf-area removed) compared with 27% of leaves in 2009 presumably due to a lack of herbivorous insect regulation by birds. Our results suggest that the extremel warm spring of 2010 altered linkages between migratory birds and their invertebrate prey that are typica during years of average weather, which likely affected habitat use and the delivery of ecosystem regulatin services.
File: Wood&Pidgeon 2015 Ecosphere.pdf
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Context Threats to wildlife species from extrem events, such as droughts, are predicted to increase i frequency and magnitude with climate change. Extrem events can cause mortality and community-leve changes, but for some mobile species, movemen away from areas affected may be a viable option Objectives We examined the effect of extrem weather on spatial patterns of abundance for a irruptive grassland bird species, the Dickcissel (Spiz americana) Methods We calculated route-level annual abundance and abundance anomalies from 1980 to 201 from North American Breeding Bird Survey data, an classified the Dickcissel’s range into core and edg regions using these abundances. We then compare abundances in the core and edge regions to th standardized precipitation evapotranspiration index, measure of drought, in linear regressions Results We found that Dickcissel irruptions in th northern range edges were related to drought condition in the range core, potentially a consequence o birds being ‘pushed’ to the range edge when weathe was unsuitable. Specifically, Dickcissels moved int refuge sites containing a high proportion of cultivate crops, with higher vegetation greenness, than thos areas they leave during drought years Conclusions In a changing climate where more frequen extreme weather may be more common, conservatio strategies for weather-sensitive species ma require consideration of habitat in the edges of species’ranges, even though non-core areasmay be unoccupied i ‘normal’ years. Our results highlight the conservatio importance of range edges in providing refuge fro extreme events, such as drought, and climate change.
File: Bateman et al 2015_Landscape Ecology Dickcissel.pdf
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In South American highland forests, domestic grazing can cause major changes in forest structure and soi quality thereby altering resources available to avian communities. However, the consequences of change in variability in plant growth forms after disturbance are little known. Understanding forest successio effects on avifauna is critical though, given that area in secondary forests is expected to increase in th future. We sampled bird communities at 172 sample points in Polylepis shrublands and forests patche in Argentina. For each of these points, we calculated vegetation variables (NDVI, NDVI texture indices) landscape pattern variables (patch area and connectivity), and human disturbance variables (erosion, distance to settlements and roads), based on a Landsat 5 TM image, a local land cover map, and topograph (slope and altitude) from a Digital Elevation Model. Bird communities in Polylepis forests include approximately twice as many species and double the abundance than those in shrublands. Species compositio strongly differed between the two growth forms as well, birds that use the ground vegetation t nest and forage were less abundant in shrubland patches, air foragers were also less abundant in shrublan patches. Soil erosion, proximity to human settlements and forest isolation were the best predictor of bird richness and abundance in Polylepis vegetation patches. Abundance of birds that use the groun for nesting and foraging were negatively related to soil erosion. We concluded that Polylepis avifaun communities are primarily influenced by human impact on soils rather than by vegetation structura characteristics. Polylepis vegetation restoration and reduction of livestock grazing would likely reduce soi erosion rates, promote natural regeneration, increase patch connectivity and enhance microhabitat condition for avifauna in high-altitude Polylepis forests and shrublands.
File: Bellis-et-al-2015_FEM.pdf
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As people encroach increasingly on natural areas, one question is how this affects avian biodiversity. The answer to this is partly scale-dependent. At broad scales, human populations and biodiversity concentrate in the same areas and are positively associated, but at local scales people and biodiversity are negatively associated with biodiversity. We investigated whether there is also a systematic temporal trend in the relationship between bird biodiversity and housing development. We used linear regression to examine associations between forest bird species richness and housing growth in the conterminous United States over 30 years. Our data sources were the North American Breeding Bird Survey and the 2000 decennial U.S. Census. In the 9 largest forested ecoregions, housing density increased continually over time. Across the conterminous United States, the association between bird species richness and housing density was positive for virtually all guilds except ground nesting birds. We found a systematic trajectory of declining bird species richness as housing increased through time. In more recently developed ecoregions, where housing density was still low, the association with bird species richness was neutral or positive. In ecoregions that were developed earlier and where housing density was highest, the association of housing density with bird species richness for most guilds was negative and grew stronger with advancing decades. We propose that in general the relationship between human settlement and biodiversity over time unfolds as a 2-phase process. The first phase is apparently innocuous; associations are positive due to coincidence of low-density housing with high biodiversity. The second phase is highly detrimental to biodiversity, and increases in housing density are associated with biodiversity losses. The long-term effect on biodiversity depends on the final housing density. This general pattern can help unify our understanding of the relationship of human encroachment and biodiversity response.
File: Pidgeon_etal_ConsBio_2014_0.pdf
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Applications of remote sensing for biodiversity conservation typically rely on image classifications that do not capture variability within coarse land cover classes. Here, we compare two measures derived from unclassified remotely sensed data, a measure of habitat heterogeneity and a measure of habitat composition, for explaining bird species richness and the spatial distribution of 10 species in a semi-arid landscape of New Mexico.We surveyed bird abundance from 1996 to 1998 at 42 plots located in the McGregor Range of Fort Bliss Army Reserve. Normalized Difference Vegetation Index values of two May 1997 Landsat scenes were the basis for among-pixel habitat heterogeneity (image texture), and we used the raw imagery to decompose each pixel into different habitat components (spectral mixture analysis). We used model averaging to relate measures of avian biodiversity to measures of image texture and spectral mixture analysis fractions. Measures of habitat heterogeneity, particularly angular second moment and standard deviation, provide higher explanatory power for bird species richness and the abundance of most species than measures of habitat composition. Using image texture, alone or in combination with other classified imagery-based approaches, for monitoring statuses and trends in biological diversity can greatly improve conservation efforts and habitat management.
File: StLouis_etal_PhilTrns_2014_0.pdf
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Protected areas are a cornerstone for biodiversity conservation, but they also provide amenities that attract housing development on inholdings and adjacent private lands. We explored how this development affects biodiversity within and near protected areas among six ecological regions throughout the United States. We quantified the effect of housing density within, at the boundary, and outside protected areas, and natural land cover within protected areas, on the proportional abundance and proportional richness of three avian guilds within protected areas. We developed three guilds from the North American Breeding Bird Survey, which included Species of Greatest Conservation Need, land cover affiliates (e.g., forest breeders), and synanthropic species associated with urban environments. We gathered housing density data for the year 2000 from the U.S. Census Bureau, and centered the bird data on this year. We obtained land cover data from the 2001 National Land Cover Database, and we used single- and multiple-variable analyses to address our research question. In all regions, housing density within protected areas was positively associated with the proportional abundance or proportional richness of synanthropes, and negatively associated with the proportional abundance or proportional richness of Species of Greatest Conservation Need. These relationships were strongest in the eastern forested regions and the central grasslands, where more than 70% and 45%, respectively, of the variation in the proportional abundance of synanthropes and Species of Greatest Conservation Need were explained by housing within protected areas. Furthermore, in most regions, housing density outside protected areas was positively associated with the proportional abundance or proportional richness of synanthropes and negatively associated with the proportional abundance of land cover affiliates and Species of Greatest Conservation Need within protected areas. However, these effects were weaker than housing within protected areas. Natural land cover was high with little variability within protected areas, and consequently, was less influential than housing density within or outside protected areas explaining the proportional abundance or proportional richness of the avian guilds. Our results indicate that housing development within, at the boundary, and outside protected areas impacts avian community structure within protected areas throughout the United States.
File: Wood_etal_2014_EcoApps.pdf
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Numerous measures of human influence on the environment exist, but one that is of particular importance is houses as they can impact the environment from species through the landscape level. Furthermore, because the addition of houses represents an important component of landscape change, housing information could be used to assess ecological responses (e.g., decline in wildlife habitat) to that change. Recently developed housing density data represents a potential source of information to assess landscape and habitat change over long periods of time and at broad spatial extents, which is critically needed for conservation and management. Considering the potential value of housing data, our goal was to demonstrate how changes in the number of houses leads to changes in the amount of habitat across the landscape, and in-turn, how these habitat changes are likely to influence the distribution and abundance for a species of conservation concern, the Ovenbird (Seiurus aurocapillus). Using a relationship between Ovenbird abundance and housing density, we predict suitable habitat in the forests of Massachusetts (USA) from 1970 to 2030. Over this 60-year period, the number of houses was projected to increase from 1.84 to 3.32 million. This magnitude of housing growth translates into a 57 % decline in Ovenbird habitat (6,002 km2 to 2,616 km2), a minimum decline of ~850,000 (48 %) Ovenbirds, and an increase in the number of subpopulations across the landscape. Overall, housing data provide important information to robustly measure landscape and habitat change, and hence predict population change of a species. We suggest that time series of housing data linked to ecological responses (e.g., Ovenbird abundance) offers a novel and underutilized approach to estimating long-term and spatially broad predictions of ecosystem response to landscape change, which in turn can inform conservation and management.
File: Lepczyk-et-al-2013-HousingDynamics.pdf
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A major challenge for biodiversity conservation is to mitigate the effects of future environmental change, such as land use, in important areas for biodiversity conservation. In the United States, recent conservation efforts by The Nature Conservancy and partners have identified and mapped the nation's Areas of Biodiversity Significance (ABS), representing the best remaining habitats for the full diversity of native species and ecosystems, and thus the most important and suitable areas for the conservation of native biodiversity. Our goal was to understand the potential consequences of future land use changes on the nation's ABS, and identify regions where ABS are likely to be threatened due to future land use expansion. For this, we used an econometric-based model to forecast land use changes between 2001 and 2051 across the conterminous U.S. under alternative scenarios of future land use change. Our model predicted a total of 100,000 to 160,000 km2 of natural habitats within ABS replaced by urban, crop and pasture expansion depending on the scenario (5% to 8% habitat loss across the conterminous U.S.), with some regions experiencing up to 30% habitat loss. The majority of the most threatened ABS were located in the Eastern half of the country. Results for our different scenarios were generally fairly consistent, but some regions exhibited notable difference from the baseline under specific policies and changes in commodity prices. Overall, our study suggests that key areas for conserving United States' biodiversity are likely threatened by future land use change, and efforts trying to preserve the ecological and conservation values of ABS will need to address the potential intensification of human land uses.
File: Martinuzzi_Ecosphere_2013.pdf
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Most of our knowledge of reproduction of wild parrots in the Neotropics comes from studies of tropical lowland species, with few studies addressing species of high-altitude forests. We studied the reproductive biology of Tucuman Parrots (Amazona tucumana) in north-western Argentina between 2004 and 2009. We obtained data on reproductive output for 86 nests and on causes of mortality for 94 nests. Mean clutch-size per nesting attempt was 3.6 eggs 1.0 (s.d.). Hatching success (proportion of eggs laid that hatch) was 0.77 0.17. Fledging success (proportion of nestlings that fledge) was 0.83 0.13. The overall breeding success (mean number of fledglings per laying female per year) was 2.3 0.8. Overall finite nesting success (daily survival rate to the power of the nesting length) was 0.53 0.27, and chick finite nesting success rate was 0.74 0.22. We did not find differences in reproductive rate between Tucuman Parrots and other species of Amazona parrot from lowland habitats. Productivity and nesting success of Tucuman Parrots had high values in some years and low values in others. This was probably related to fruiting events of Podocarpus parlatorei - a critical food item. The main causes of nesting failure were predation (16%) and abandonment (12%). Our results suggest that for several species of Amazona in lowland habitats, predation and poaching may be the main limiting factors whereas climatic factors and food availability may contribute most to nesting failure at higher altitudes.
File: Rivera_etal_2013_Emu.pdf
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