March research news from the Ecological Society of America
image:
A study in Frontiers in Ecology and the Environment uses data on shorebirds like these to demonstrate a new approach to understanding and protecting migratory birds amid habitat change.
view moreCredit: Tong Mu
The Ecological Society of America (ESA) presents a roundup of five research articles recently published across its esteemed journals. Widely recognized for fostering innovation and advancing ecological knowledge, ESA’s journals consistently feature illuminating and impactful studies. This compilation of papers explores supply and demand along birds’ migration routes, scavenging by smaller carnivores, polar bear adaptation to a thawing Arctic, how different forestry approaches affect Europe’s birds and beaver impacts on tundra ecosystems.
From Frontiers in Ecology and the Environment:
Measuring the supply and demand of bird migration
Author contact: Tong Mu (tmu@princeton.edu)
Pinpointing where migrating birds most need help has long been difficult, because changes in their numbers at any one site can reflect not just local conditions but also shifting circumstances elsewhere along their journeys. To address this challenge, the authors of a new study introduce a simple but powerful metric grounded in two ideas they call “demand” (how intensely birds use a site) and “supply” (the site’s capacity to provide needed resources, such as food and shelter). By comparing bird demand with habitat supply, the metric can be used to assess and compare the relative conditions of stopover sites along migratory routes. Sites with high demand but low supply may represent potential bottlenecks — places heavily used by migrating birds yet limited in resources — while sites with ample supply but lighter use may be of lower conservation concern. Because this framework can be applied across entire migration routes, it can enhance management and conservation efficiency by helping prioritize sites to safeguard and shedding light on which factors may be limiting migratory bird populations throughout their ranges.
Read the article: A “demand and supply” approach to monitoring habitat and population changes of migratory birds
From Ecology:
Mid-size carnivores selective about scavenging
Author contact: Wesley Binder (wesley.binder@oregonstate.edu)
Research in the western U.S. suggests that scavenging by mid-sized carnivores differs depending on which large predator did the killing. Camera traps and GPS tracking of coyotes and red foxes in Yellowstone National Park showed that both so-called “mesocarnivores” took advantage of the scraps left over by wolves and cougars. Unexpectedly, however, the preferences of the two mesocarnivores differed markedly: foxes were frequently encountered at cougar kills but only rarely at wolf kills, while coyotes largely avoided cougar kills and stuck closer to wolves. Overlapping lifestyles may account for these associations to some degree, as wolves and coyotes are typically active during the day, whereas cougars and red foxes are most active after dusk. But cougars are also known to actively hunt coyotes for food, a behavior rarely displayed by wolves, which may explain why coyotes shy away from the big cats. Still, being kin is no guarantee of safety: wolves often attack coyotes lurking around kill sites because they perceive their smaller cousins to be rivals for limited resources. The research provides new insights into how the presence of large carnivores shapes the behavior of mesocarnivores, knowledge that may aid global management and conservation of carnivores of all sizes.
Read the article: Species-specific interactions with apex carnivores yield unique benefits and burdens for mesocarnivores
From Ecological Monographs:
Polar bears barely adapting to climate change
Author contact: L. Ruth Rivkin (ruth.rivkin@umanitoba.ca)
As polar bears struggle with multiple accelerating challenges in a rapidly warming Arctic, scientists have now pulled together the first comprehensive review of what we know about how the species is responding evolutionarily to these changes. Although genetic variation is essential for adapting to shifting environmental conditions, the review finds that this capacity is becoming more constrained in some — but not all — populations of polar bears. Shrinking sea ice is making it harder for bears to hunt and interact with each other, interfering with normal population mixing and, in some regions, leading to signs of significant inbreeding. Climate change, along with subsistence hunting and other human pressures, may also be causing bears to become smaller, a typical response to warmer conditions and more unpredictable food supplies. Despite these changes, however, scientists have detected little evidence of true physiological adaptation; instead, bears appear to be coping primarily by altering their behavior, such as hunting for new kinds of prey. By bringing together scattered genetic and ecological studies, the review highlights an urgent need to integrate these data streams to improve monitoring and protection of wide-ranging animals like polar bears, especially in regions of the world where climate change is already causing significant upheaval.
Read the article: Climate-linked evolution and genetics in a warming Arctic
From Ecological Applications:
Balancing timber and wildlife in Europe’s managed forests
Author contact: João Manuel Cordeiro Pereira (jmpereira94@hotmail.com)
Different approaches for balancing logging and biodiversity in European forests have varying — and sometimes contrasting — impacts on both birds and the insects they feed on, according to a recent study. Analysis of 1,394 bird surveys conducted across 135 forest plots in southern Germany showed that management practices that create more natural forest conditions, namely variable retention (leaving some living and dead trees and downed logs during harvest) and close-to-nature forestry (replacing uniform evergreen monocultures with uneven-aged stands of a variety of trees) often supported higher abundances of certain bird species, particularly those that nest in cavities or rely on diverse forest structure. Yet the direction of these responses varied widely among birds, underscoring that no single management strategy benefits all birds and that a mosaic of differently structured forests is likely needed. Invertebrates like insects and spiders also responded to these forestry practices, but bird numbers did not simply track the amount of their prey; rather, birds and invertebrates tended to respond in parallel to features such as higher shares of broadleaf trees or richer understories. Overall, the results point to the importance of moving beyond evergreen-dominated monocultures to support birds and their prey in Europe’s managed forests.
Read the article: Disentangling the effects of multifunctional forestry practices on the abundances of birds and their invertebrate prey
From Ecosphere:
Eager beavers busy moving north
Author contact: Georgia M. Hole (georgia.m.hole@durham.ac.uk)
Integrating physical evidence with remote-sensing techniques has enabled researchers to map the expansion of beavers into the Canadian Arctic, shedding additional light on the myriad ways they are transforming polar ecosystems. Natural clues — felled trees, browsed vegetation and altered waterways — left behind by the industrious engineers indicate that beavers have continuously occupied the study region bordering the Arctic Ocean since around 2008. In turn, the use of satellite imagery reveals some of the ways in which beavers are altering northern landscapes, such as rapid formation of ponds upstream from dams, creation of extensive wetland systems and rerouting of waterways. The results underscore the usefulness of linking different lines of evidence for determining beaver movement into Arctic regions and for anticipating their impacts on fragile tundra environments.
Read the article: Dendrochronology and remote sensing reveal beaver occupancy and colonization dynamics in an expanding Arctic population
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The Ecological Society of America, founded in 1915, is the world’s largest community of professional ecologists and a trusted source of ecological knowledge, committed to advancing the understanding of life on Earth. The 8,000 member Society publishes six journals and a membership bulletin and broadly shares ecological information through policy, media outreach and education initiatives. The Society’s Annual Meeting attracts thousands of attendees and features the most recent advances in ecological science. Visit the ESA website at https://www.esa.org
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