Fledgling Theories

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).

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/

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).

'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!

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.

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). 

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).

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).

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!

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).