Episodes
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One side effect of our collective global coffee addiction is the transformation of native forest into coffee plantations. But are all coffee plantations created equal? How does shade grown coffee match up to the native forest it replaces? Can it still be good habitat for birds? Canada Warblers make a long trek each year from their breeding grounds in the high latitude forests of North America to their wintering grounds in South America, and they need high quality fuel when they get there. We're diving into a study that works to find out how well shade coffee measures up to native forest for these weary travelers. Find the article and follow along here: "Contrasting the suitability of shade coffee agriculture and native forest as overwinter habitat for Canada Warbler (Cardellina canadensis) in the Columbian Andes" (Gonzalez et al, 2020).
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We usually think about natural selection making small changes, generation by generation, over long time spans. But during extreme weather events, high mortality means natural selection acts fast. How do these extreme events drive evolution? At a long term study site in Nebraska, researchers took advantage of continuous Cliff Swallow monitoring to look at the effects of three extreme weather events in the last 30 years, finding opposite selection pressures for similar climatic events. Check out the article here: "Changing patterns of natural selection on the morphology of Cliff Swallows during severe weather" (Brown et al 2018). To learn more about the long term monitoring project, check out their nice website here: https://www.cliffswallow.org/
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We might assume it's because the grass is greener on the other side. But this month's study suggests that some migrant Sanderlings headed to the tropics are getting less than they bargained for. Tune in to our chat about the costs and benefits of migration, the importance of falsifying hypotheses, the logistics of studying a species over 13,000 kilometers, and how wintering habitat can make or break success on the breeding grounds. Find the article here: "Low fitness at low latitudes: Wintering in the tropics increases migratory delays and mortality rates in an Arctic breeding shorebird" (Reneerkens et al 2019).
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'Tis the season for caroling.... and some of us enunciate better than others. On its wintering grounds in Tanzania, the Thrush Nightingale sings an inconsistent, disjointed version of its beautiful, complex song. Why? In what ways is its winter song different from its breeding song? This month, we're chatting about a paper that tests the theory that these birds are using their wintering grounds to warm up and rehearse before the big show of the breeding season. Join us for a chat about Souriau et al's "Singing behind the stage: thrush nightingales produce more variable songs on their wintering grounds" (2019).
In other exciting news, we've launched a Patreon page! If you enjoy the podcast, please consider supporting us here: https://www.patreon.com/fledglingtheories. Your donation helps support our mission of effective science communication, and gets you access to bonus content!
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Flying is a dangerous business. Birds must dodge trees, powerlines, windows. Anyone who has seen a robin flit at full speed into a dense thicket knows birds have an extraordinary ability to avoid obstacles if they can see them. But some obstacles seem particularly challenging. This episode's study looks at a single 260 meter section of powerline into which hundreds of Sandhill Cranes crash annually. Can knowledge from fundamental research help us come up with practical solutions? And how do researchers manage questions of ethics when testing solutions? Join us for a chat about "Near-ultraviolet light reduced Sandhill Crane collisions with a power line by 98%" (Dwyer et al, 2019). Find the correction to the article here.
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In TV advertisements, it seems paper towels can always absorb more grape juice. Are urban areas similarly able to take in more and more introduced bird species? Does this species absorption have a limit? In this episode, Willson and Ellie don't know, can't agree, and so speculate wildly while discussing the study "Alien species richness is currently unbounded in all but the most urbanized bird communities" (Tsang, Dyer & Bonebrake 2019).
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Studying birds typically involves in-person observation, but with the rapid advance of high quality audio recorders and microphones, bird researchers are finding they can have "ears" in many places at once these days. How do audio recordings of birds compare to observing them in person? What information do we lose when we don't have visual observations? And what do we stand to gain by using these remote monitoring techniques? This month we're discussing "Bird biodiversity assessments in temperate forest: the value of point count versus acoustic monitoring protocols" (Klingbeil & Willig, 2015).
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Not all brood parasites are on the hunt for an unsuspecting bird of another species to take advantage of. In fact, there are many bird species who lay the occasional egg in the nest of a same-species neighbor. But is this behavior actually parasitic? For many waterfowl species, it may be that both host and egg-layer benefit from the arrangement. Join us for part II of our brood parasite mini-series, as we discuss "Brood parasitism, relatedness, and sociality: a kinship role in female reproductive tactics" (Andersson, Ahlund & Waldeck, 2019).
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Is there an evolutionary arms race between birds trying to hide eggs and birds trying to find eggs? If so, who is racing who? Brood parasites (like many species of Cowbird and Cuckoo) lay their eggs in other birds' nests to trick a host species into raising their chicks. It's easy to imagine that all the drama and competition arise from conflict between an unwilling host species and sneaky parasite. But what if the parasite birds' main competitors are other parasites? This month, we're chatting all about this nesting strategy and the possible evolutionary drivers of one parasite's stealth adaptations. Read the paper here: "Grey Gerygone hosts are not egg rejecters, but Shining Bronze-Cuckoos lay cryptic eggs," (Thorogood et al, 2017).
This is part I of a two-part mini-series on brood parasites; check back in August for part II!
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Feeding the birds is big business these days, but how has all that food availability affected bird communities? It turns out that your feeder (combined with all your neighbors' feeders across the nation) has probably helped influence population change and bird community composition! We're discussing "The composition of British bird communities is associated with long-term garden bird feeding" (Plummer et al 2019).
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Do birds get used to people walking past? Today we are talking about whether birds in rural and urban areas differ in how easily they are spooked by passers by, both human and... well, umbrellan. To hear more about the role of eyed umbrellas in bird research, tune in to our discussion of "Predictors of flight behavior in rural and urban songbirds" (Battle, Folz, & Moore 2016).
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Specially adapted antbird species can track and follow army-ant swarms in the Ecuadorian forest to take advantage of the arthropods the ants flush from the forest floor. But there may be other birds hoping to take advantage of these ant swarms-- if they can find them. This month, we're talking about the intriguing tale of intercepted communication between ant-following species with the article "Interspecific information use by army-ant-following birds" (Batcheller 2017).
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No matter where you live, you probably see some bird species that seem to stay put all year long. But did you know these species might still be migrating? Today we're talking partial migration-- where some individuals of a species migrate and some are resident. Why does this happen? Which species do this? How can we even tell?? Check out the article here: "Where do winter crows go? Characterizing partial migration of American Crows with satellite telemetry, stable isotopes and molecular markers" (Townsend et al 2018).
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Does it help or hurt a plant to have birds eat their seeds? Birds can help plants by moving their seeds to new places, but what happens to seeds inside birds’ guts? For some plants, seeds that pass through a bird’s gut may actually be at an advantage compared to seeds that never get eaten. But does that depend on the bird species, or the plant species, or both? Tune in to our discussion of Fricke et al's "Functional outcomes of mutualistic network interactions: A community-scale study of frugivore gut passage on germination."
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Long running, citizen science data collection projects like the Audubon Society's Christmas Bird Count and the North American Breeding Bird Survey are more than just a fun excuse to get out and bird with other people! In fact, together they provide 60 years of comprehensive data tracking relative bird abundance in North America (and the CBC alone provides almost 120 years of winter bird data!). We're ringing in the new year with a discussion about how a festive and fun winter birding event like the CBC can actually help predict the future distribution of an invasive species just making its way into North America-- the Eurasian Collared Dove.
Check out the article here: "Range Expansion and Population Dynamics of an Invasive Species: The Eurasian Collared-Dove" (Scheidt & Hurlbert, 2014).
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For the endangered Saltmarsh Sparrow, nesting is a pick-your-battles endeavour. Nest too far below the high tide line, and you could lose your babies to flooding. Nest too far above the high tide line, and parasites may invade the nest, spreading disease and robbing parents and juveniles of valuable body mass. What's a bird to do?! This month we're talking about evolutionary trade-offs and the article, "Tidal flooding is associated with lower ectoparasite intensity in nests of the Saltmarsh Sparrow" (Nightingale & Elphick, 2017).
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Like Peter Pan, migrating birds fly through the night, straight on 'til morning... but then what? Usually as dawn arrives, birds make landfall in suitable stopover habitat. But if they find themselves over the Great Lakes in the northern USA as the sun rises, how do they deal with this obstacle? What happens to the height birds are flying and the direction they're oriented when they encounter these water bodies? With the help of weather radar stations, we can find out. Check out the article here: "Migrating birds reorient toward land at dawn over the Greak Lakes, USA" (Archibald et al, 2017).
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Roughly 100 years ago, some Yellowhammers (Emberiza citrinella) were captured in England and released in New Zealand. They successfully bred there, establishing a new population. Since then, what has happened to the way these birds sing? How has 100 years of separation between the New Zealand and Great Britain populations affected the dialects of Yellowhammers that live in each of these places? And why do bird dialects matter? Jump in to the world of bird song with us as we discuss "Dialects of an invasive songbird are preserved in its invaded but not native source range" (Pipek et al, 2018).
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Stable isotopes are a pretty hot topic in bird research these days. But what are they, and how are they used? What can isotopes tell us about where and how birds are migrating? This month, we look at what the combined forces of isotopes and geolocators can tell us about Barn Swallow migration, as we discuss Keith Hobson & Kevin Kardynal's 2016 study, "An isotope (δ34S) filter and geolocator results constrain a dual feather isoscape (δ2H, δ13C) to identify the wintering grounds of North American Barn Swallows." Already familiar with the use of isotopes in biological research? Feel free to skip to minute 7:00.
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As the planet gets warmer and spring comes earlier each year, birds may have to adjust their spring behaviors and migration timing to keep up with the weather! But what happens when bird populations fail to adjust their nesting and migration timing to the new, earlier advance of spring? How does a mismatch between the bird breeding season and the arrival of spring (flowers blooming, insects emerging, etc.) affect bird populations? In this episode, Ellie and Willson talk about Franks et al's study, "The sensitivity of breeding songbirds to changes in seasonal timing is linked to population change but cannot be directly attributed to the effects of trophic asynchrony on productivity."
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