We’re getting a lot of questions about flies and panting this week! Although the weather has warmed, leaves have not yet unfurled to shade our nests. While it may not seem hot to human watchers, the eaglets are in direct sunlight and their woolly thermal down is better at keeping them warm than cooling them off.
Our sweat glands secrete water on to the surface of our skin. When it evaporates, we cool down. Since birds don’t have sweat glands, they pant, seek shade, and sprawl out over cool surfaces to bring their temperatures down. You’ll see several of these strategies in today’s Decorah North mega-roll, including eaglet and eagle panting, DN9 crawling under Mr. North for shade, Mr. North standing between DN9 and the sun, and Mr. North pulling up cool nesting materials from deep inside the nest bowl to pile next to DN9 (since Mr. North stands in them, he may also getting some relief). While panting looks alarming, it is a normal response to warm temperatures. Leaves are unfurling and their shade will soon help keep eaglets and eagles a little cooler. Too bad we don’t have some of those fishcicles from earlier this year!
How about flies? Watchers worried that the flies we’re seeing might be black flies. Black flies carry a pathogen than can cause illness, especially in downy eaglets, and their bites can cause subcutaneous hemorrhaging. However, we’re not seeing black flies yet. I don’t have a for-sure genus or species, but the flies we are seeing now appear to be more along the line of bottle flies, a member of the family Calliphoridae. Bottle flies are distinguished by their distinctive coloration and loud buzzing flight. They also lay their eggs in rotting flesh, which would describe their presence in the nest – and the prevalence of maggots in some of the nestovers! We will write more about black flies, bottle flies, and other gnest gnasties later this week or early next.
On to the NestFlix! Tonight’s mega-roll features the Decorah North Eagles. While I loved all of these videos, do not miss ‘Food stuck in the throat of the eaglet’ (I’m not sure that is what happened, but the crop action is fascinating!) or the priceless interaction between DN9 and Mr. North! It’s an adorable video, but also a really good example of the ways in which parent eagles protect and care for their eaglets. Cold isn’t the only weather challenge eagle parents face!
4/23/19: Mr. North & DN9 Sharing a Fish Dinner – https://youtu.be/uyYzXRz8W-E. Because I love watching Mr. North and DN9 together! But Mr. North seems to be doing more eating than sharing – perhaps because DN9 is so full it doesn’t want anything but a nap in the shade!
4/23/19: DNF cast a pellet – https://youtu.be/OrAOSfh3r78. Eagles compress indigestible materials like fur, scales, and feathers into a pellet and expel them from their mouths. Eagle pellets are very large, but this is impressive even by eagle standards! Watch the whole thing or start at 17 seconds. That thing in DNF’s mouth? It’s not her tongue! She finally gets the whole very large pellet out at 24 seconds!
4/22/19: Food stuck in the throat of the eaglet – https://youtu.be/bc7rFowWfVw. I’m not sure whether food was stuck, DN9 was trying to cast a pellet (see the video above), or something was interfering with a crop drop, since the ‘retching’ movement started before Mr. North started plucking the coot. Watch the whole thing or start at 10:20, where DN9 has stepped back from the coot with a crop substantially larger than its head. At 10:31, it lifts its head up and down and appears to squeeze or contract its muscles as though trying to shift the crop – not at all the ‘yawning’ technique we are used to. It repeats this action several times and appears to have a (somewhat) diminished crop at 11:10 (and 13:34) as it steps back to table for more coot!
4/21/19: A warm Easter day – https://youtu.be/-nXEkVbpnvg. The nest rocks back and forth in a cooling breeze, but that doesn’t stop the eagles from panting! DN9 is 21 days old and growing very rapidly. It sleeps in DNF’s shade (eaglets this age do a lot of eating, sleeping, and pooping), eats some nestovers (judging from DN9’s crop, it’s eating the equivalent of several Thanksgiving meals a day), and goes back to dozing in the shade – a lovely way to spend a lazy Easter Sunday!
4/21/19: Interaction Between Nr. North & DN9, Priceless – https://youtu.be/zqkRoGS8_RA. DN9 doesn’t have a sibling, but it does have two devoted parents! After a PS, DN9 moves over to Mr. North for a game of leapfrog! Mr. North stands next to DN9, providing shade for the panting eaglet and appearing at one point to try to tuck DN9 underneath it – something DN9 is a little big for. Still, DN9 wants a little shade and manages to tuck under Mr. North as far as it can! At 4:02, Mr. North begins digging in the nestbowl. He reaches deep down to pull up cool, moist-looking grasses, which he piles next to DN9. At 4:31, DN9 begins moving grasses with his dad, building a little berm in front of him. Cooling down, playing house, or both? Mr. North pulls up a huge tuft (watch him watch DN9 early in the 5th minute) and DN9 tastes it before plopping crop-first into it. Mr. North, also panting, moves into position to provide more shade. Look for a ‘boop’ at 6:25, a nibble at 6:29, and another nibble at 7:16.
Thanks to our camera operators for finding special moments in the nest, our video makers for sharing them, and you for watching them!
The Raptor Resource Project