Fledgling Theories

Is that umbrella looking at me? And other concerns of an urban bird

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).

Antbird Espionage

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). 

This little birdie migrated, this little birdie stayed home

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). 

Feathered Fruit Peelers

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."

Your Christmas Bird Count data at work!

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). 

Floods and Plagues, Ticks vs. Tides

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).

Fly straight on 'til morning... then what?

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).

Auditory Archive: Yellowhammer dialects across two countries and 100 years

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).

Feathery Chemistry: using isotopes to track migration

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. 

Spring timing! Can birds adjust to match the arrival of spring? Does it even matter?

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."