Climatic extremes influence spring tree phenology and migratory songbird foraging behavior

In the Upper Midwest of the United States,
fire suppression has resulted in succession of
savanna and forests that differ in both plant community composition and vegetation structure from
their condition prior to Euro-American settlement. Furthermore, variations in weather affect
spring phenological events and potentially alter
synchronous relationships of migratory songbirds
with their seasonal resources. Our goal here was
to understand how annual variation in phenology of four tree species—northern red oak (Quercus
rubra), eastern white oak (Q. alba), sugar maple
(Acer saccharum), and red maple (A. rubrum)—affect
foraging behavior of migratory songbirds during
spring migration. Oaks currently have poor regeneration, whereas maples have good regeneration
in forests in the Upper Midwest. A typical temperature regime in 2009 coupled with a record
warm winter and early spring in 2010 provided a
natural experiment for addressing our goal. In the
spring and early summer of 2009 and 2010, we
monitored migratory songbird foraging behavior
and collected data on tree flowering and leaf-out
phenology for 160 replicate trees of the four study
species at the Kickapoo Valley Reserve in southwest Wisconsin. In 2009, 15 species of migratory wood-warbler (F. Parulidae) arrived at the
stopover study area in late April and were present
until late May. Birds foraged heavily on flowering
northern red oak and, to a lesser extent, on flowering eastern white oak and sugar maple. Red maple
was not preferred by wood-warblers. In 2010, the
arrival date and duration of stay among the 15 species of wood-warblers was similar to 2009, yet
the frequency of use of the four tree species was
reduced by 60%. Northern red oak, sugar maple,
and red maple achieved summer condition 2 to
3 weeks earlier in 2010 than 2009, but these tree
species were not preferred by the wood-warblers.
Instead, eastern white oak, which flowered from
early to late May, was the preferred foraging substrate in 2010. Our findings suggest that the flowering and early leaf-out phase of trees provides
important resources to migrant wood-warblers
that are apparently absent from trees that are more
phenologically advanced. Our results also suggest
that managing for heterogeneity in tree species,
including early and late flowering species, as well
as maintaining early successional tree species in
the landscape, may be an important consideration
in maintaining wood-warbler population levels
under a variety of climate conditions.

File: Wood__Pidgeon_2015_Studies_in_Avian_Biology_Phenology.pdf

In the Upper Midwest of the United States,
fire suppression has resulted in succession of
savanna and forests that differ in both plant community composition and vegetation structure from
their condition prior to Euro-American settlement. Furthermore, variations in weather affect
spring phenological events and potentially alter
synchronous relationships of migratory songbirds
with their seasonal resources. Our goal here was
to understand how annual variation in phenology of four tree species—northern red oak (Quercus
rubra), eastern white oak (Q. alba), sugar maple
(Acer saccharum), and red maple (A. rubrum)—affect
foraging behavior of migratory songbirds during
spring migration. Oaks currently have poor regeneration, whereas maples have good regeneration
in forests in the Upper Midwest. A typical temperature regime in 2009 coupled with a record
warm winter and early spring in 2010 provided a
natural experiment for addressing our goal. In the
spring and early summer of 2009 and 2010, we
monitored migratory songbird foraging behavior
and collected data on tree flowering and leaf-out
phenology for 160 replicate trees of the four study
species at the Kickapoo Valley Reserve in southwest Wisconsin. In 2009, 15 species of migratory wood-warbler (F. Parulidae) arrived at the
stopover study area in late April and were present
until late May. Birds foraged heavily on flowering
northern red oak and, to a lesser extent, on flowering eastern white oak and sugar maple. Red maple
was not preferred by wood-warblers. In 2010, the
arrival date and duration of stay among the 15 species of wood-warblers was similar to 2009, yet
the frequency of use of the four tree species was
reduced by 60%. Northern red oak, sugar maple,
and red maple achieved summer condition 2 to
3 weeks earlier in 2010 than 2009, but these tree
species were not preferred by the wood-warblers.
Instead, eastern white oak, which flowered from
early to late May, was the preferred foraging substrate in 2010. Our findings suggest that the flowering and early leaf-out phase of trees provides
important resources to migrant wood-warblers
that are apparently absent from trees that are more
phenologically advanced. Our results also suggest
that managing for heterogeneity in tree species,
including early and late flowering species, as well
as maintaining early successional tree species in
the landscape, may be an important consideration
in maintaining wood-warbler population levels
under a variety of climate conditions.

Bird conservation in the Carpathian ecoregion in light of long-term land use trends and conservation responsibility

Land use change alters species’ abundance and distributions by affecting habitat
availability and quality. The decline of bird populations worldwide is of major concern,
and habitat protection and restoration are primary conservation actions. However, conservation
decisions largely consider only short-term habitat changes and species’ population
dynamics in a given area. Disregarding long term modifications in species’ available habitat,
and the role of a given population for a species’ global population may lead to misdirected
conservation action. Our goal here was to combine the assessment of conservation
responsibility, with that of century-long available habitat dynamics, in order to inform
better conservation practice. We compiled available habitat data for 170 bird species in
the Carpathian Region from 1860 to 2010 from historic maps and satellite data. We analyzed
these species’ range distributions, IUCN extinction risk and population trends, and
we identified 29 species of high conservation responsibility, and all of them were forest or
and grassland specialists. Furthermore, we found major land use trends including cropland
abandonment and increase in forests and grasslands that resulted in increases in potential
habitat for the species for which the Carpathians have high conservation responsibility. The
loss of row-crop agriculture, on the other hand, reduced habitat for species for which the
Carpathians do not have high responsibility, and thus subsidizing agriculture may not be
warranted from a conservation perspective. More broadly, many regions worldwide are
undergoing rapid land use changes, and we suggest that these should be analyzed relative to a given regions’ conservation responsibility to see if there are opportunities for conservation,
i.e., cases similar to the Carpathians, where conservation efforts ‘only’ have to foster
current land use trends, and make them permanent, rather than to try to revert the loss
of habitat.

File: Munteanu2018_Article_BirdConservationInTheCarpathia.pdf

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Novel foraging by wintering Siberian Cranes Leucogeranus leucogeranus at China’s Poyang Lake indicates broader changes in the ecosystem and raises new challenges for a critically endangered species

Following an abnormal flood in 2010 at China’s Poyang Lake, we observed wintering Siberia Cranes Leucogeranus leucogeranus switch from foraging in the shallow-water wetlands the typically use to grassland habitats. These previously undocumented habitat selection pattern raised questions whether differences in crane behaviour such as foraging success existed betwee the two habitats and how those differences might affect this critically endangered species. Ove two winters, we used the density of customary food items (tubers of Vallisneria spp.) obtaine from long-term monitoring efforts, Siberian Cranes flock behaviours, individual foraging succes and estimated total flock foraging effort across both habitats. Novel foraging patterns by Siberia Cranes were associated with low densities of Vallisneria tubers across multiple sub-lakes withi Poyang Lake National Nature Reserve (PLNR). Foraging success was higher in grasslands tha in wetlands in winter 2010–2011, but higher in wetlands following a recovery of Vallisneria i 2011–2012. Subsequent to upland foraging during the winter of 2010–2011, we observed lowe juvenile to adult ratio of Siberian Cranes at a fall migratory stopover location in north-easter China despite indications of average environmental conditions in the nesting areas from 2010 t 2012. While grasslands adjacent to shallow-water habitats may be important refugia for winterin Siberian Cranes when Vallisneria is absent or inaccessible, and should be included in protecte areas, multi-year dependence on grasslands for foraging could negatively impact populatio levels. Eliminating crab farming in protected areas and extending protection to shallow wate areas sheltered from flooding by dykes could also help secure high quality foraging habitat unde a variety of hydrological regimes. Novel foraging patterns by wintering Siberian Cranes represen a new challenge to the conservation efforts for this species that focus on shallow-water wetlands and may be indicative of broader changes within Poyang’s ecosystem.

File: Burnham_etal_2017_Siberian_Novel_Foraging_Poyang.pdf

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Using the North American Breeding Bird Survey to assess broad-scale responses of the continent’s most imperiled avian community, grassland birds, to weather variability

Avian populations can respond dramatically to extreme weather such as droughts and heat waves, yet patterns o response to weather at broad scales remain largely unknown. Our goal was to evaluate annual variation in abundance o 14 grassland bird species breeding in the northern mixed-grass prairie in relation to annual variation in precipitation an temperature. We modeled avian abundance during the breeding season using North American Breeding Bird Surve (BBS) data for the U.S. Badlands and Prairies Bird Conservation Region (BCR 17) from 1980 to 2012. We used hierarchica Bayesian methods to fit models and estimate the candidate weather parameters standardized precipitation index (SPI and standardized temperature index (STI) for the same year and the previous year. Upland Sandpiper (Bartrami longicauda) responded positively to within-year STI (b ¼ 0.101), and Baird’s Sparrow (Ammodramus bairdii) responde negatively to within-year STI (b ¼ 0.161) and positively to within-year SPI (b ¼ 0.195). The parameter estimates wer superficially similar (STI b ¼ 0.075, SPI b ¼ 0.11) for Grasshopper Sparrow (Ammodramus savannarum), but the bestselecte model included an interaction between SPI and STI. The best model for both Eastern Kingbird (Tyrannu tyrannus) and Vesper Sparrow (Pooecetes gramineus) included the additive effects of within-year SPI (b ¼0.032 and b ¼0.054, respectively) and the previous-year’s SPI (b¼0.057 and0.02, respectively), although for Vesper Sparrow the la effect was insignificant. With projected warmer, drier weather during summer in the Badlands and Prairies BCR, Baird’ and Grasshopper sparrows may be especially threatened by future climate change

File: Gorzo_etal_2016_Condor.pdf

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Potential breeding distributions of U.S. birds predicted with both short-term variability and long-term climate data

Climate conditions, such as temperature or precipitation, averaged over several decades strongly affect species distributions, as evidenced by experimental results and a plethora of models demonstrating statistical relations between species occurrences and long- term climate averages. However, long- term averages can conceal climate changes that have occurred in recent decades and may not capture actual species occurrence well because the distributions of species, especially at the edges of their range, are typically dynamic and may respond strongly to short- term climate variability. Our goal here was to test whether bird occurrence models can be predicted by either covariates based on short- term climate variability or on long- term climate averages. We parameterized species distribution models (SDMs) based on either short- term variability or long- term average climate covariates for 320 bird species in the conterminous USA and tested whether any life- history trait- based guilds were particularly sensitive to short- term conditions. Models including short- term climate variability performed well based on their cross- validated area- under- the- curve AUC score (0.85), as did models based on long- term climate averages (0.84). Similarly, both models performed well compared to independent presence/absence data from the North American Breeding Bird Survey (independent AUC of 0.89 and 0.90, respectively). However, models based on short- term variability covariates more accurately classified true absences for most species (73% of true absences classified within the lowest quarter of environmental suitability vs. 68%). In addition, they have the advantage that they can reveal the dynamic relationship between species and their environment because they capture the spatial fluctuations of species potential breeding distributions. With this information, we can identify which species and guilds are sensitive to climate variability, identify sites of high conservation value where climate variability is low, and assess how species’ potential distributions may have already shifted due recent climate change. However, long- term climate averages require less data and processing time and may be more readily available for some areas of interest. Where data on short- term climate variability are not available, long- term climate information is a sufficient predictor of species distributions in many cases. However, short- term climate variability data may provide information not captured with long- term climate data for use in SDMs.

File: Bateman_et_al-2016-Ecological_Applications.pdf

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The pace of past climate change vs. potential bird distributions and land use in the United States

Climate change may drastically alter patterns of species distributions and richness, but predicting future species pat-terns in occurrence is challenging. Significant shifts in distributions have already been observed, and understanding these recent changes can improve our understanding of potential future changes. We assessed how past climate change affected potential breeding distributions for landbird species in the conterminous United States. We quantified the bioclimatic velocity of potential breeding distributions, that is, the pace and direction of change for each species’ suitable climate space over the past 60 years. We found that potential breeding distributions for landbirds have shifted substantially with an average velocity of 1.27 km yr1, about double the pace of prior distribution shift esti-mates across terrestrial systems globally (0.61 km yr1). The direction of shifts was not uniform. The majority of species’ distributions shifted west, northwest, and north. Multidirectional shifts suggest that changes in climate conditions beyond mean temperature were influencing distributional changes. Indeed, precipitation variables that were proxies for extreme conditions were important variables across all models. There were winners and losers in terms of the area of distributions; many species experienced contractions along west and east distribution edges, and expansions along northern distribution edges. Changes were also reflected in the potential species richness, with some regions potentially gaining species (Midwest, East) and other areas potentially losing species (Southwest). How-ever, the degree to which changes in potential breeding distributions are manifested in actual species richness depends on landcover. Areas that have become increasingly suitable for breeding birds due to changing climate are often those attractive to humans for agriculture and development. This suggests that many areas might have sup-ported more breeding bird species had the landscape not been altered. Our study illustrates that climate change is not only a future threat, but something birds are already experiencing.

File: Bateman_et_al-2016-Global_Change_Biology.pdf

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Identifying areas of optimal multispecies conservation value by accounting for incompatibilities between species

Conservation planning is designed to optimize conservation actions when only limited resources ar available for managing habitats and mitigating threats, and excels at selecting reserve networks tha protect the largest number of species. However, the spatial optimization of the protection of multipl species can be complicated by interactions among those species and incompatibilities in their habita needs. The challenge is to identify an optimal solution when two species with similar habitat needs canno co-occur. We propose here a new approach to find the optimal conservation planning solution i cases of species incompatibilities, and demonstrate this solution for a 144 km2 area (a 160,000-cell grid in northern Wisconsin. Specifically, our study objectives were to simultaneously (a) identify the smalles area needed to meet minimum habitat requirements for every species considered, (b) maximize th compactness of that area, and (c) avoid any overlap between species with incompatible habitat requirements We found an optimized solution based on potential habitat models for 19 bird species using novel application of mixed integer linear programming, with a clustering approach suited for large cel arrays. Under this solution, 9.9% of the study plot was sufficient to meet the minimum requirement for every species considered, maximize the compactness of that area, and avoid any overlap betwee species with incompatible habitat requirements. Our results are useful to assist managers in providin well-connected, sufficient habitat to at-risk species while minimizing costs and land use conflicts.

File: Beaudryetal_2016_Ecological%20Modeling.pdf

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Will representation targets based on area protect critical resources for conservation of the Tucumán Parrot?

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%20et%20al.%202015_condor-14-214.pdf

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Extreme variations in spring temperature affect ecosystem regulating services provided by birds during migration

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%202015%20Ecosphere.pdf

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