Ecological and life-history traits explain recent boundary shifts in elevation and latitude of western North American songbirds

Buckley L.B., Kingsolver J.G.

Shifts in phenology and distribution in response to both recent and paleontological climate changes vary markedly in both direction and extent among species. These individualistic shifts are inconsistent with common forecasting techniques based on environmental rather than biological niches. What biological details could enhance forecasts? Organismal characteristics such as thermal and hydric limits, seasonal timing and duration of the life cycle, ecological breadth and dispersal capacity, and fitness and evolutionary potential are expected to influence climate change impacts. We review statistical and mechanistic approaches for incorporating traits in predictive models as well as the potential to use phylogeny as a proxy for traits. Traits generally account for a significant but modest fraction of the variation in phenological and range shifts. Further assembly of phenotypic and phylogenetic data coupled with the development of mechanistic approaches is essential to improved forecasts of the ecological consequences of climate change.

Van der Putten W.H.

Changes in climate, land use, fire incidence, and ecological connections all may contribute to current species' range shifts. Species shift range individually, and not all species shift range at the same time and rate. This variation causes community reorganization in both the old and new ranges. In terrestrial ecosystems, range shifts alter aboveground-belowground interactions, influencing species abundance, community composition, ecosystem processes and services, and feedbacks within communities and ecosystems. Thus, range shifts may result in no-analog communities where foundation species and community genetics play unprecedented roles, possibly leading to novel ecosystems. Long-distance dispersal can enhance the disruption of aboveground-belowground interactions of plants, herbivores, pathogens, symbiotic mutualists, and decomposer organisms. These effects are most likely stronger for latitudinal than for altitudinal range shifts. Disrupted aboveground-belowground interactions may have influenced historical postglacial range shifts as well. Assisted migration without considering aboveground-belowground interactions could enhance risks of such range shift–induced invasions.

Betzholtz P., Pettersson L.B., Ryrholm N., Franzén M.

Recent global change has had a substantial influence on the distribution of organisms, and many species are currently expanding their ranges. To evaluate the underlying processes, long-term data with good geographic resolution are essential. One important but generally overlooked data source is offered by the taxon-specific national catalogues of first provincial records that are kept in many countries. Here, we use such data to quantify trait-based influences on range expansion in Swedish butterflies and moths between 1973 and 2010. Of 282 species meeting pre-defined quality criteria, 170 expanded their northern range margin, with a mean expansion rate of 2.7 km per year. The analyses demonstrate that habitat and diet generalists, forest species and species active during warm conditions have expanded their ranges more rapidly than other species. Notably, range expansion in diet specialists was positively related to a nitrogen-favoured larval diet, an effect not found among oligo- or polyphagous species. In contrast to the general view, this shows that specialist species can undergo rapid range expansion. We suggest that increased areas of nitrogen-rich habitat, and increased availability of a nitrogen-favoured diet, are among the most important drivers of range expansions, potentially having far-reaching consequences for a wide variety of organisms.

Kujala H., Vepsäläinen V., Zuckerberg B., Brommer J.E.

Global climate warming is predicted to lead to global and regional changes in the distribution of organisms. One influential approach to test this prediction using temporally repeated mapping surveys of organisms was suggested in a seminal paper by Thomas & Lennon (1999, Nature). The Thomas & Lennon approach corrects observed changes in the range margin for changes in the range size, and thus potentially controls for other broad-scale environmental changes between surveys, however the approach does not necessarily account for potential biases in sampling effort. To verify whether the issue of variation in sampling effort affects empirical estimates of shifts in range margin, we reanalyzed all three published studies exploring range margin changes of breeding birds in Great Britain (GB), Finland, and New York State (NY). Accounting for changes in survey effort on range margins lowered the estimated shift for breeding birds in New York, but the shift remained statistically significant. For Great Britain and Finland, for which no direct estimate of survey effort is available, we used species richness (a strong correlate of survey effort in New York) as a proxy and found that in both cases the estimated shift in range margin was significantly reduced and became nonsignificant. To understand how robust the approach is to sampling biases, we use a simulation model to show that the Thomas & Lennon approach is, under certain conditions, sensitive to changes in detection probability (probability to detect true occupancy) which in turn may be affected by changes in surveying effort between surveys. We thus found evidence that temporal changes in the distribution of breeding birds based on repeated mapping surveys may be inflated by changes in survey effort along range boundaries. We discuss possible approaches to deal with this issue in the analysis and design of national or regional surveys.

Diffenbaugh N.S., Giorgi F.

We use a statistical metric of multi-dimensional climate change to quantify the emergence of global climate change hotspots in the CMIP5 climate model ensemble. Our hotspot metric extends previous work through the inclusion of extreme seasonal temperature and precipitation, which exert critical influence on climate change impacts. The results identify areas of the Amazon, the Sahel and tropical West Africa, Indonesia, and the Tibetan Plateau as persistent regional climate change hotspots throughout the 21st century of the RCP8.5 and RCP4.5 forcing pathways. In addition, areas of southern Africa, the Mediterranean, the Arctic, and Central America/western North America also emerge as prominent regional climate change hotspots in response to intermediate and high levels of forcing. Comparisons of different periods of the two forcing pathways suggest that the pattern of aggregate change is fairly robust to the level of global warming below approximately 2 °C of global warming (relative to the late-20th-century baseline), but not at the higher levels of global warming that occur in the late-21st-century period of the RCP8.5 pathway, with areas of southern Africa, the Mediterranean, and the Arctic exhibiting particular intensification of relative aggregate climate change in response to high levels of forcing. Although specific impacts will clearly be shaped by the interaction of climate change with human and biological vulnerabilities, our identification of climate change hotspots can help to inform mitigation and adaptation decisions by quantifying the rate, magnitude and causes of the aggregate climate response in different parts of the world.

Tingley M.W., Koo M.S., Moritz C., Rush A.C., Beissinger S.R.

Projected effects of climate change on animal distributions primarily focus on consequences of temperature and largely ignore impacts of altered precipitation. While much evidence supports temperature-driven range shifts, there is substantial heterogeneity in species' responses that remains poorly understood. We resampled breeding ranges of birds across three elevational transects in the Sierra Nevada Mountains, USA, that were extensively surveyed in the early 20th century. Presence–absence comparisons were made at 77 sites and occupancy models were used to separate significant range shifts from artifacts of false absences. Over the past century, rising temperature pushed species upslope while increased precipitation pulled them downslope, resulting in range shifts that were heterogeneous within species and among regions. While 84% of species shifted their elevational distribution, only 51% of upper or lower range boundary shifts were upslope. By comparison, 82% of range shifts were in a direction predicted by changes in either temperature or precipitation. Species were significantly more likely to shift elevational ranges than their ecological counterparts if they had small clutch sizes, defended all-purpose territories, and were year-round residents, results that were in opposition to a priori predictions from dispersal-related hypotheses. Our results illustrate the complex interplay between species-specific and region-specific factors that structure patterns of breeding range change over long time periods. Future projections of increasing temperature and highly variable precipitation regimes create a strong potential for heterogeneous responses by species at range margins.

Sol D., Maspons J., Vall-llosera M., Bartomeus I., García-Peña G.E., Piñol J., Freckleton R.P.

Successful Invaders Invasive species have been integrated into ecosystems worldwide, and in many cases can cause significant ecological and economic damage. Not all non-native species, however, become invasive species; thus there has been much effort put toward understanding what makes a non-native “colonizer” an invader. It has been thought that, in general, successful invaders tend to be those that produce a large amount of offspring over a very short period of time, however, this pattern is absent in many successful invaders. Sol et al. (p. 580 ) looked at over 2700 invasions by bird species across the world and found no relationship between population growth rate and invasion success, although rapidly reproducing species could have an advantage when the new environment resembled their native environment. Furthermore, in many cases, those species that could prioritize survival, and delay reproduction, were much more successful than those forced to reproduce regardless of environmental conditions.

Schloss C.A., Nuñez T.A., Lawler J.J.

As they have in response to past climatic changes, many species will shift their distributions in response to modern climate change. However, due to the unprecedented rapidity of projected climatic changes, some species may not be able to move their ranges fast enough to track shifts in suitable climates and associated habitats. Here, we investigate the ability of 493 mammals to keep pace with projected climatic changes in the Western Hemisphere. We modeled the velocities at which species will likely need to move to keep pace with projected changes in suitable climates. We compared these velocities with the velocities at which species are able to move as a function of dispersal distances and dispersal frequencies. Across the Western Hemisphere, on average, 9.2% of mammals at a given location will likely be unable to keep pace with climate change. In some places, up to 39% of mammals may be unable to track shifts in suitable climates. Eighty-seven percent of mammalian species are expected to experience reductions in range size and 20% of these range reductions will likely be due to limited dispersal abilities as opposed to reductions in the area of suitable climate. Because climate change will likely outpace the response capacity of many mammals, mammalian vulnerability to climate change may be more extensive than previously anticipated.

Booth E.L., Byrne J.M., Johnson D.L.

The rate of climatic change over western North America (WNA) is quantified for 485 climate stations for the period 1950–2005. Additionally, six stations with quality long-term records were selected and analysed for the period 1906–2005. The indicators used were developed by the World Meteorological Organization (WMO) and the World Climate Research Program's Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI). From the 27 core indices, 4 temperature-based and 4 precipitation-based indicators were selected for in-depth analysis. The 8 million km2 study area is comprised of the 22 contiguous US states and 4 Canadian provinces west of the Mississippi River and Great Lakes. The results were divided into six general regions for interpretation and presentation. GIS interpolation of station-specific statistical output was completed to further aid in the identification of spatially coherent trends across WNA. Mean slopes were calculated over the whole study area, and by region, for each index, and then tested to determine if they were significantly different from zero. Results of the study show statistically significant historical climate trends across the study area. As expected in a region as geographically diverse as WNA, results differed between, and within, regions. Overall, temperature-based indicators showed a general warming trend over the entire study area, with the greatest increases along the North American Cordillera. The trends in precipitation-based indicators were more varied. General trends indicate moderately increasing precipitation volume and intensity over much of WNA. The strongest precipitation trends were found in areas with climate largely controlled by air masses originating over the Gulf of Mexico. Copyright © 2011 Royal Meteorological Society

Forero-Medina G., Terborgh J., Socolar S.J., Pimm S.L.

Background Species may respond to a warming climate by moving to higher latitudes or elevations. Shifts in geographic ranges are common responses in temperate regions. For the tropics, latitudinal temperature gradients are shallow; the only escape for species may be to move to higher elevations. There are few data to suggest that they do. Yet, the greatest loss of species from climate disruption may be for tropical montane species. Methodology/Principal Findings We repeat a historical transect in Peru and find an average upward shift of 49 m for 55 bird species over a 41 year interval. This shift is significantly upward, but also significantly smaller than the 152 m one expects from warming in the region. To estimate the expected shift in elevation we first determined the magnitude of warming in the locality from historical data. Then we used the temperature lapse rate to infer the required shift in altitude to compensate for warming. The range shifts in elevation were similar across different trophic guilds. Conclusions Endothermy may provide birds with some flexibility to temperature changes and allow them to move less than expected. Instead of being directly dependent on temperature, birds may be responding to gradual changes in the nature of the habitat or availability of food resources, and presence of competitors. If so, this has important implications for estimates of mountaintop extinctions from climate change.

Chen I., Hill J.K., Ohlemüller R., Roy D.B., Thomas C.D.

A meta-analysis shows that species are shifting their distributions in response to climate change at an accelerating rate.

Angert A.L., Crozier L.G., Rissler L.J., Gilman S.E., Tewksbury J.J., Chunco A.J.

Although some organisms have moved to higher elevations and latitudes in response to recent climate change, there is little consensus regarding the capacity of different species to track rapid climate change via range shifts. Understanding species' abilities to shift ranges has important implications for assessing extinction risk and predicting future community structure. At an expanding front, colonization rates are determined jointly by rates of reproduction and dispersal. In addition, establishment of viable populations requires that individuals find suitable resources in novel habitats. Thus, species with greater dispersal ability, reproductive rate and ecological generalization should be more likely to expand into new regions under climate change. Here, we assess current evidence for the relationship between leading-edge range shifts and species' traits. We found expected relationships for several datasets, including diet breadth in North American Passeriformes and egg-laying habitat in British Odonata. However, models generally had low explanatory power. Thus, even statistically and biologically meaningful relationships are unlikely to be of predictive utility for conservation and management. Trait-based range shift forecasts face several challenges, including quantifying relevant natural history variation across large numbers of species and coupling these data with extrinsic factors such as habitat fragmentation and availability.

Jacobsen F., Friedman N.R., Omland K.E.

Darwin's vision of a "Tree of Life" showing evolutionary relationships among all extant species seems an increasingly feasible goal, at least for vertebrate animals. However, virtually all published molecular phylogenies for closely related animals are based on a single locus - maternally inherited mitochondrial DNA. New approaches using multiple nuclear loci are needed to test published trees and better resolve the twigs of the entire tree of life. Here we use New World orioles (Icterus) to test an approach based on combined analysis of six independent Z chromosome introns. Combined analysis of multiple introns using traditional phylogenetic methods resolved a well-supported species phylogeny of New World orioles. In fact, all major lineages of orioles and several sub-clades that are well-supported by previously published mtDNA data are also strongly supported by the combined nuclear Z-intron tree. The male-biased Z-intron tree presented here is overwhelmingly congruent with the female-exclusive mtDNA tree. A slow rate of mutation relative to mtDNA resulted in generally poorly resolved gene trees when intron loci were analyzed separately. However, strong phylogenetic signal for all but the most recent divergences emerged once multiple loci were concatenated and analyzed in combination. Although there clearly are conditions under which concatenation analysis of nuclear DNA can be misleading, the congruence between mitochondrial and nuclear estimates of the Icterus phylogeny suggests that concatenation remains a powerful tool for inferring phylogenetic relationships for all but very recent divergences.

Van der Putten W.H., Macel M., Visser M.E.

Current predictions on species responses to climate change strongly rely on projecting altered environmental conditions on species distributions. However, it is increasingly acknowledged that climate change also influences species interactions. We review and synthesize literature information on biotic interactions and use it to argue that the abundance of species and the direction of selection during climate change vary depending on how their trophic interactions become disrupted. Plant abundance can be controlled by aboveground and belowground multitrophic level interactions with herbivores, pathogens, symbionts and their enemies. We discuss how these interactions may alter during climate change and the resulting species range shifts. We suggest conceptual analogies between species responses to climate warming and exotic species introduced in new ranges. There are also important differences: the herbivores, pathogens and mutualistic symbionts of range-expanding species and their enemies may co-migrate, and the continuous gene flow under climate warming can make adaptation in the expansion zone of range expanders different from that of cross-continental exotic species. We conclude that under climate change, results of altered species interactions may vary, ranging from species becoming rare to disproportionately abundant. Taking these possibilities into account will provide a new perspective on predicting species distribution under climate change.

Beever E.A., Ray C., Mote P.W., Wilkening J.L.

Biotic responses to climate change will vary among taxa and across latitudes, elevational gradients, and degrees of insularity. However, due to factors such as phenotypic plasticity, ecotypic variation, and evolved tolerance to thermal stress, it remains poorly understood whether losses should be greatest in populations experiencing the greatest climatic change or living in places where the prevailing climate is closest to the edge of the species' bioclimatic envelope (e.g., at the hottest, driest sites). Research on American pikas (Ochotona princeps) in montane areas of the Great Basin during 1994-1999 suggested that 20th-century population extirpations were predicted by a combination of biogeographic, anthropogenic, and especially climatic factors. Surveys during 2005-2007 documented additional extirpations and within-site shifts of pika distributions at remaining sites. To evaluate the evidence in support of alternative hypotheses involving effects of thermal stress on pikas, we placed temperature sensors at 156 locations within pika habitats in the vicinity of 25 sites with historical records of pikas in the Basin. We related these time series of sensor data to data on ambient temperature from weather stations within the Historical Climate Network. We then used these highly correlated relationships, combined with long-term data from the same weather stations, to hindcast temperatures within pika habitats from 1945 through 2006. To explain patterns of loss, we posited three alternative classes of direct thermal stress: (1) acute cold stress (number of days below a threshold temperature); (2) acute heat stress (number of days above a threshold temperature); and (3) chronic heat stress (average summer temperature). Climate change was defined as change in our thermal metrics between two 31-yr periods: 1945-1975 and 1976-2006. We found that patterns of persistence were well predicted by metrics of climate. Our best models suggest some effects of climate change; however, recent and long-term metrics of chronic heat stress and acute cold stress, neither previously recognized as sources of stress for pikas, were some of the best predictors of pika persistence. Results illustrate that extremely rapid distributional shifts can be explained by climatic influences and have implications for conservation topics such as reintroductions and early-warning indicators.

Dai S., Zhou Y., Gao J., Cheng G., Wang L., Bai H., Lei X., Xu H., Mao X.

Vickers S.H., Meehan T.D., Michel N.L., Franco A.M., Gilroy J.J.

Abstract Background Many species are exhibiting range shifts associated with anthropogenic change. For migratory species, colonisation of new areas can require novel migratory programmes that facilitate navigation between independently-shifting seasonal ranges. Therefore, in some cases range-shifts may be limited by the capacity for novel migratory programmes to be transferred between generations, which can be genetically and socially mediated. Methods Here we used 50 years of North American Breeding Bird Survey and Audubon Christmas Bird Count data to test the prediction that breeding and/or non-breeding range-shifts are more prevalent among flocking migrants, which possess a capacity for rapid social transmission of novel migration routes. Results Across 122 North American bird species, social migration was a significant positive predictor for the magnitude of non-breeding centre of abundance (COA) shift within our study region (conterminous United States and Southern Canada). Across a subset of 81 species where age-structured flocking was determined, migrating in mixed-age flocks produced the greatest shifts and solo migrants the lowest. Flocking was not a significant predictor of breeding COA shifts, which were better explained by absolute population trends and migration distance. Conclusions Our results suggest that social grouping may play an important role in facilitating non-breeding distributional responses to climate change in migratory species. We highlight the need to gain a better understanding of migratory programme inheritance, and how this influences spatiotemporal population dynamics under environmental change.

Pu J., Guo W., Zhang H., Wang W.

Gaya H.E., Chandler R.B.

ABSTRACT Many populations near receding low-latitude range: margins are declining in response to climate change, but most studies of trailing-edge populations have focused on single species. Using 10 years (2014–2023) of avian survey data from a high-elevation trailing-edge population hotspot in the Appalachian Mountains, USA, we tested the hypothesis that high-elevation communities would experience turnover through thermophilization, as warm-adapted species near the center of their geographic ranges expand into regions formerly dominated by peripheral populations of cool-adapted species. Three of the nine cool-adapted, peripheral populations decreased in abundance, and whereas 6 species exhibited little change. For warm-adapted populations near the core of their range, 1 of 16 decreased in abundance, 11 increased, and 4 exhibited no change. Within the most abundant species in this community, our results indicate that warm-adapted species are expanding their ranges faster than the rate at which ranges of cool-adapted species are contracting. Avoiding future community turnover may require conservation strategies that maintain microclimates for cool-adapted species facing novel abiotic and biotic conditions at high elevations.

Howard J.A., DuVall A.J., Pereksta D.M., Mazurkiewicz D.M., Searcy A.J., Capitolo P.J., Russell T.M.

McCreadie J.W., Adler P.H.

AbstractWe explored how the ratio of blood‐feeding behaviour—nonfeeding, bird feeding (ornithophily) and mammal feeding (mammalophily)—and voltinism (univoltine and multivoltine) vary over a latitudinal gradient from Alaska to Florida. These two fixed species traits were divided into five mutually exclusive combinations of trait states—nonfeeding/univoltine, ornithophilic/univoltine, mammalophilic/univoltine, ornithophilic/multivoltine and mammalophilic/multivoltine—within each of three datasets (north, east and west). We found a significant association between location (north, east and west) and trait state, which was driven by the large percentage of nonfeeding females in the north. When this trait state was removed, no significant differences were found for the remaining trait states and locations. Although the distribution of trait states did not differ between east and west datasets, the distribution with relation to 1° changes in latitude within each of these datasets showed distinct differences. In the east, both ornithophilic/univoltine and mammalophilic/univoltine species significantly increased with latitude, in proportion to the total species present. In contrast, the proportion of mammalophilic/multivoltine species decreased as latitude increased. Ornithophilic/multivoltine species in the east and the trait states in the west did not show any significant relationship to latitude.

Kaiser S.A., Forg L.E., Stillman A.N., Deitsch J.F., Sillett T.S., Clucas G.V.

AbstractChanges in leaf phenology from warming spring and autumn temperatures have lengthened the temperate zone growing “green” season and breeding window for migratory birds in North America. However, the fitness benefits of an extended breeding season will depend, in part, on whether species have sufficient dietary flexibility to accommodate seasonal changes in prey availability. We used fecal DNA metabarcoding to test the hypothesis that seasonal changes in the diets of the insectivorous, migratory black‐throated blue warbler (Setophaga caerulescens) track changes in the availability of arthropod prey at the Hubbard Brook Experimental Forest, New Hampshire, USA. We examined changes across the breeding season and along an elevation gradient encompassing a 2‐week difference in green season length. From 98 fecal samples, we identified 395 taxa from 17 arthropod orders; 242 were identified to species, with Cecrita guttivitta (saddled prominent moth), Theridion frondeum (eastern long‐legged cobweaver), and Philodromus rufus (white‐striped running crab spider) occurring at the highest frequency. We found significant differences in diet composition between survey periods and weak differences among elevation zones. Variance in diet composition was highest late in the season, and diet richness and diversity were highest early in the season. Diet composition was associated with changes in prey availability surveyed over the green season. However, several taxa occurred in diets more or less than expected relative to their frequency of occurrence from survey data, suggesting that prey selection or avoidance sometimes accompanies opportunistic foraging. This study demonstrates that black‐throated blue warblers exhibit diet flexibility and track seasonal changes in prey availability, which has implications for migratory bird responses to climate‐induced changes in insect communities with longer green seasons.

Neate-Clegg M.H., Tonelli B.A., Tingley M.W.

Terrestrial species can respond to a warming climate in multiple ways, including shifting in space (via latitude or elevation) and time (via phenology). Evidence for such shifts is often assessed independent of other temperature-tracking mechanisms; critically, no study has compared shifts across all three spatiotemporal dimensions. Here we used two continental-scale monitoring databases to estimate trends in the breeding latitude (311 species), elevation (251 species) and phenology (111 species) of North American landbirds over 27 years, with a shared pool of 102 species. We measured the magnitude of shifts and compared them relative to average regional warming (that is, shift ratios). Species shifted poleward (1.1 km per year, mean shift ratio 11%) and to higher elevations (1.2 m per year, mean shift ratio 17%), while also shifting their breeding phenology earlier (0.08 days per year, mean shift ratio 28%). These general trends belied substantial variation among species, with some species shifting faster than climate, whereas others shifted more slowly or in the opposite direction. Across the three dimensions (n = 102), birds cumulatively tracked temperature at 33% of current warming rates, 64% of which was driven by advances in breeding phenology as opposed to geographical shifts. A narrow focus on spatial dimensions of climate tracking may underestimate the responses of birds to climate change; phenological shifts may offer an alternative for birds—and probably other organisms—to conserve their thermal niche in a warming world. Analysis of North American landbirds compares their latitudinal, elevational and phenological responses to climate change. Species have tracked 33% of current temperature change, with phenological change accounting for the majority (64%) of this.

Xing X., Wang X., Li X., Lan F., Deng Z., Li Y., Li Q., Ding Z.

Birds are sensitive to environmental changes and can drive range shifts rapidly due to their high mobility. Though previous studies have examined the associations between species traits and range shifts, whether species traits could still explain heterogeneity in shift directions remains poorly explored. Here, we compiled new bird records of China from 2000 to 2019 and analyzed species traits associated with apparent shift directions. We collected 350 provincial-level new records of birds belonging to 67 families of 22 orders. Of these, 32 are threatened, with 3 critically endangered, 11 endangered, and 18 vulnerable. Provinces in western China (i.e., Yunnan and Xizang) had relatively higher species richness of new recorded birds; this pattern was also reflected in the phylogenetic diversity we observed. In addition, provinces in northern China (i.e., Tianjin, Shandong, and Beijing) had relatively higher richness-controlled phylogenetic diversity. Phylogenetic overdispersion of new recorded bird communities was observed in 61.29% of provinces (19 of 31). The main shift directions indicated by new bird records were northward (with nearly 50% of birds moving NW, N and NE). Migration, hand-wing index (HWI), body mass, and range size are the four key factors that most significantly influence the shift directions in bird species, suggesting that bird movement toward newly suitable areas varies with species-specific traits. Together, these results demonstrate the importance of considering species ecological traits when predicting shift directions of birds.

Zillig M.W., Brooks W., Fleishman E.

Montane species are generally predicted to respond to climate change via upslope movement. Elevational range shifts of birds rarely have been examined in arid regions. Here, we examine shifts in the elevational distributions of breeding birds from two regions of the Great Basin, a desert in the western USA, over 10 to 20 years. We collected data annually from 2001 to 2020, a relatively long and consistent time series that is uncommon in research on distributional shifts. We used single‐species occupancy models of 32 bird species to examine shifts along the full elevational gradient (1650–3200 m a.s.l.) and within the lowest and highest edges (25%) of the gradient. We then conducted simulations to test whether population stochasticity could confound inferences about shifts. We examined whether temperature, precipitation, and primary productivity (normalized difference vegetation index) were associated with occupancy and shifts. The elevational distributions of 23 species shifted, and simulations indicated that shifts in the distributions of 18 species were unlikely to be stochastic. The majority of shifts in the western Great Basin were downslope, whereas those in the central Great Basin were upslope. More shifts occurred at the edges of the elevational gradient than along the full gradient. Elevational shifts lacked a consistent climate‐response signal, but those of some species appeared to follow changes in primary productivity. We found regional differences in elevational shifts and climate associations, and our work suggests that these desert bird populations may be relatively resilient to climate change.

Raymundo A., Micheletti T., Haché S., Stralberg D., Stewart F.E., Tremblay J.A., Barros C., Eddy I.M., Chubaty A.M., Leblond M., Mahon C.L., Van Wilgenburg S.L., Bayne E.M., Schmiegelow F., Docherty T.D., et. al.

Climate change presents a major threat to biodiversity globally. Northern ecosystems, such as Canada's boreal forest, are predicted to experience particularly severe climate-induced changes. These changes may reduce the carrying capacity and habitat suitability of the boreal forest for many wildlife species. Boreal birds are susceptible to both direct and indirect effects of climate change, and several studies have predicted northward shifts in species distributions as temperatures become warmer. We forecasted spatially-explicit changes in the densities of 72 boreal landbird species using integrated climate change projections and a forest dynamics model in the Taiga Plains ecozone of the Northwest Territories (NT), Canada, over the 2011–2091 horizon. We 1) identified "winner," "loser," and "bellringer" species over short (2031) and long-term (2091) forecasts, 2) mapped landbird range and density changes under three contrasting Global Circulation Models (GCMs), and 3) quantify differences in landbird density predictions across a latitudinal gradient. Species that showed a moderate increase or decrease in their predicted abundance were considered "winners" and "losers," respectively. Species that showed a marked increase or decrease – a doubling or halving – of their predicted abundance in all three GCMs, were termed "bellringers". From 2011–2031, only 2/72 (2.8%) were considered winners, and 3/72 (4.2%) were losers. From 2011–2091, the abundance of more species was predicted to change: 26/72 (36.1%) were winners, and 10/72 species (13.9%) were losers. Four species were considered bellringers: Gray-cheeked Thrush, White-crowned Sparrow, Fox Sparrow, and American Tree Sparrow. Overall, projected range shifts were strongly oriented along a southeast-to-northwest axis. Shifts to the north and south were evenly distributed among all three GCMs. Our results suggest that future climate-mitigated distribution shifts and population declines of boreal landbirds will require targeted conservation actions. They also highlight the importance of the NT as a potential refugium for many boreal-breeding landbird species in Canada.

Anufriev V.V., Punantsev E.A.

This paper presents data on the distribution of the black grouse Lyrurus tetrix (L., 1758), capercaillie Tetrao urogallus (L., 1758), and hazel grouse Tetrastes bonasia (L., 1758) in the Nenets Autonomous Area (the northeast of the European Russian Federation). The study has revealed trends indicating an expansion of the distribution range of these species to the north. According to our observations, black grouse, capercaillie, and hazel grouse in the Malozemelskaya Tundra are located further north than in the published data – about 40 km for black grouse, 20 km for capercaillie, and 20 km for hazel grouse. In the Malozemelskaya Tundra, the northernmost black grouse and capercaillie were found in spruce forest islands, while the hazel grouse inhabited riverine floodplain forests. In the Bolshezemelskaya Tundra, the capercaillie was the only grouse bird found further north compared to the published data, in the extremely northern islands of the forest within the Shapkina River valley. In the Bolshezemelskaya Tundra, new registrations of the grouse (200 km) and ruffed grouse (100 km) were noted to the east of the known data, indirectly indicating an expansion of the distribution area of these birds to the north in the regions adjacent to the Nenets Autonomous Area. It was noted that the trends of expansion of the range of distribution of black grouse to the north are unidirectional with positive trends in air temperature in the Nenets Autonomous Area and with the processes of gradual overgrowth of woody vegetation in treeless areas located between the forest tundra and northern spruce forest islands.

Banda L.B., Dejene S.W., Mzumara T.I., McCarthy C., Pangapanga‐Phiri I.

AbstractClimate change poses a significant threat to endemic and endangered montane bird species with limited elevation and temperature ranges. Understanding their responses to changes in climate is essential for informing conservation actions. This study focused on the montane dwelling Yellow‐throated Apalis (Apalis flavigularis) in Malawi, aiming to identify key factors affecting its distribution and predicting its potential distribution under different climate change scenarios. Using an ensemble species distribution modeling approach, we found that the mean temperature of the driest quarter (Bio9), mean temperature of the wettest quarter (Bio8), and precipitation seasonality (Bio15) were the most important variables that influenced the distribution of this species. Across future climate scenarios, the species' geographic range declined where range losses varied from 57.74% (2050 RCP 6.0) to 82.88% (2070 RCP 6.0). We estimate its current range size to be 549 km2 which is lower than some previous estimates of its spatial distribution. Moreover, our projections indicate that under future climate scenarios, the species will shift to higher elevations with a large proportion of suitable areas located outside forests, posing challenges for adaptation. Our results suggest that the species may be under greater threat than previously thought; hence, urgent conservation actions are required. We recommend reinforcing the protection of areas predicted to remain suitable under future climate scenarios and the development of a species conservation action plan.

Martins P.M., Anderson M.J., Sweatman W.L., Punnett A.J.

Changes in climate can alter environmental conditions faster than most species can adapt. A prediction under a warming climate is that species will shift their distributions poleward through time. While many studies focus on range shifts, latitudinal shifts in species’ optima can occur without detectable changes in their range. We quantified shifts in latitudinal optima for 209 North American bird species over the last 55 y. The latitudinal optimum ( m ) for each species in each year was estimated using a bespoke flexible non-linear zero-inflated model of abundance vs. latitude, and the annual shift in m through time was quantified. One-third (70) of the bird species showed a significant shift in their optimum. Overall, mean peak abundances of North American birds have shifted northward, on average, at a rate of 1.5 km per year (±0.58 SE), corresponding to a total distance moved of 82.5 km (±31.9 SE) over the last 55 y. Stronger poleward shifts at the continental scale were linked to key species’ traits, including thermal optimum, habitat specialization, and territoriality. Shifts in the western region were larger and less variable than in the eastern region, and they were linked to species’ thermal optimum, habitat density preference, and habitat specialization. Individual species’ latitudinal shifts were most strongly linked to their estimated thermal optimum, clearly indicating a climate-driven response. Displacement of species from their historically optimal realized niches can have dramatic ecological consequences. Effective conservation must consider within-range abundance shifts. Areas currently deemed “optimal” are unlikely to remain so.

López‐Ramírez S., Real R., Muñoz A.

Under the current pattern of climate change, mountain bird populations are generally shifting their ranges to higher elevations, tracking their climatic optima. Nevertheless, space limitations at high altitudes constrain mountain species' resilience to climatic change, making them particularly vulnerable. In extreme cases, the climatic niche of some species can move beyond mountaintops, ultimately driving such species to extinction. This study presents the case of the northern wheatear Oenanthe oenanthe in mainland Spain and compares its breeding distribution from 2003 to 2022. Spain, where the species mostly occupies mountain areas, represents its southernmost distribution limit in Europe. We built environmental favourability models using information from the two most recent Spanish bird atlases and a set of climatic, topographic, human activity and lithological variables to determine the factors affecting the occurrence of the species. The influence of climate compared to all other factors was obtained using variation partitioning analysis. The northern wheatear has suffered a strong reduction (67%) in occupied areas and also in favourability throughout mainland Spain (especially in the south) where climate change may have far‐reaching consequences, including local extinctions. Climate explained more than 90% of the variation in the model obtained for 2022. Interestingly, the occupied areas were, on average, 100 m higher in 2022 than in 2003. If the effects of climate warming persist, the northern wheatear will likely disappear in its southernmost distribution limit, being the Sierra de las Nieves National Park population the most vulnerable in mainland Spain. For this reason, it is necessary to implement monitoring programmes for northern wheatear populations, with priority for mountain systems wherein they already occupy higher elevations, as well as further studies on other mountain species.