[text on screen: Ask an Expert: Top Bird Migration Questions. Dr. Kevin J. McGowan, Bird Academy Senior Course Designer. Highlights from a webinar recorded in Sept 2023. Image of two Sandhill Cranes in a marsh. Logo: Cornell Lab]
[text on screen: Why do birds migrate?]
Folks ought to know that not all birds migrate.
Some birds simply keep in the identical place all yr lengthy. So if we take into consideration the birds up within the boreal forest, the chickadees keep there all yr spherical. They’ll discover, imagine it or not, insect eggs and little issues like that within the bark, that they’ll discover sufficient meals to maintain them, hold them going throughout the winter. However a variety of the opposite birds feed on flying bugs or transferring bugs, and there aren’t too a lot of these, up in Canada within the wintertime, so that they should go someplace else to search out meals. Migration is nearly all the time about discovering meals. It’s to not get out of the chilly as a result of birds can survive chilly. However there are specific inhospitable locations that they should go away. However it’s virtually all the time about meals.
[text on screen: What prompts birds to start migrating?]
Effectively, the factor that begins chook migration often is a change in daylight and what that does is that begins this type of, the, the proximate mechanism that will get the birds brains altering, totally different hormones being produced, and the birds can sense even very small modifications in daylight size. There’s this cool time period that’s in German referred to as Zugunruhe and meaning migratory restlessness.
[text on screen: Zugunruhe. Migratory Restlessness]
And so we will you may watch this. And it’s been properly studied in birds that should you hold them in captivity, as the sunshine modifications, as the times get smaller or longer, they begin to get antsy and so they simply form of transfer round of their cages and so they simply need to go someplace. And it’s simply this have to, to go additional, to go additional, go south, go south, go down, you already know.
[text on screen: How variable is migration timing?]
In truth it’s really pretty rigorous in some species. It’s very, very predictable. Like when Purple-winged Blackbirds flip up in central New York, is is all the time inside a two week interval. And so a few of these issues are very exact. Nevertheless, migration on, you already know, for a person chook relies on the, circumstances that that chook is in. And that features modifications in climate and, and native circumstances and stuff like that. So there’s all the time that type of high quality tuning. So it’s by no means exactly the identical.
[text on screen: Do adult and juvenile birds migrate together?]
Yeah, that’s an fascinating factor about migration is we are inclined to assume, oh properly, yeah, they only go—However they don’t There are totally different… totally different… the sexes do various things. And the juveniles do various things. And usually what you see going first are the males, the breeding males of a variety of totally different birds go away the breeding grounds earlier than the females or the juveniles do. After which as a… once more, as a basic rule of thumb the adults go away first after which the juveniles go away later. And it could be they only want an extended time to fatten up, emigrate. However that’s very a really predictable sample that we see
[text on screen: What’s the best time of day to migrate?]
[image: map of continental United States in purple, orange, and yellow against a black background, colors indicate predicted strength of bird migration. Text on screen: Migration intensity scale: white = High; yellow to orange = Medium; purple = Low; dark = None. 378 million birds predicted. Logo: BirdCast]
Completely different birds do migrate at totally different occasions of the day. And to, lots of people are stunned to know that the the majority of migration occurs at evening, that the majority birds fly at evening. And there’s a number of causes for this. One is that they, you already know, there are fewer predators with the ability to catch you at evening. You may’t actually forage that a lot, so that you would possibly as properly fly.
[Image: graphic of a flying Yellow Warbler against a globe depicting lines of magnetic force]
When there’s not sufficient mild to see very properly, birds can really activate a distinct sense and see the magnetic fields of the earth. And to allow them to inform north and south, as a result of they’ll see the magnetic fields. I learn that information and it’s like, oh, that’s why they fly at evening is as a result of then they’ll see. And that does appear to be the consensus is that, a variety of the nighttime flying, is as a result of that enables them to make use of their magnetic sense to detect north and south.
[text on screen: How can people help migrating birds?]
Effectively, hummingbird feeders, the hummingbirds actually like hummingbird feeders, and also you received’t make them cease migrating, and keep it up and stick along with your feeder until it will get chilly. They’re not going to try this. However they’ll use it as a supply of, low-cost power that they’ll placed on and, and, assist them alongside their approach. Suet for a few of the different birds is sweet. The opposite factor to do to assist birds alongside throughout that is flip off your lights at evening. That’s a giant one. And naturally, this actually performs out within the cities. And, and there are the applications that individuals have, various organizations are working with, together with the Cornell Lab of Ornithology, which might be attempting to encourage huge cities to chop down on their mild utilization throughout peak migration time as a result of birds get confused. And so flip off your lights at evening, plant native crops, put up a hummingbird feeder. That doesn’t do all of it. However there are a few tangible issues that individuals can do.
[text on screen: Media Credits: Oregon soundscape by Todd Sanders / Macaulay Library; Sandhill Cranes by Dylan S. / Macaulay Library; Blaack-capped Chickadee by Nick Saunders / Macaulay Library; Tree Swallow by Blair Dudeck / Macaulay Library; Whimbrels by Matt Aeberhard / Macaulay Library; Red-winged Blackbirds by Ron Beurkert / Macaulay Library; American Avocets by Matt Zuro / Macaulay Library; BirdCast Migration Forecast 6 Sept 2024 / Cornell Lab and Colorado State University; Geomagnetic illustration by Jillian Ditner / Cornell Lab; Calliope Hummingbird by Joshua Glant / Macaulay Library; Nighttime view from space by NASA / JPL.]
[soundscape of bird calls ends]
Finish of Transcript