A Northwoods Almanac for 2/18 – 3/3/22
Sightings – Redpoll Irruption and Nyjer Seed
Common redpolls have appeared in large numbers at local bird feeders over the last month. Bruce Bacon, master bird bander in Mercer, currently has 100 or more redpolls at his feeders, of which he banded at least 70 on 2/9.
This is an “irruption” year for redpolls, a phenomenon driven by widespread failures of the winter seed crops they favor – birch, alder, and spruce. Redpoll irruptions typically occur every other year, and given that their breeding range is in the far northern boreal forest, this is usually the only time they come into contact with human populations.
Redpolls are being seen as far south as Texas and Alabama, a long flight for these small songbirds!
Black oil sunflower seed serves them well, but they have a real affinity for nyjer (thistle) seed. When I spoke with Bruce last week, he noted that he had a feeder of nyjer seed up all winter, and it had been untouched. He’d heard that other folks were having this problem, and that nyjer seed can quickly spoil. So, he bought a new bag, put up a new feeder, and voila, within 24 hours, he had redpolls eating the new seed while still avoiding the old seed. At $58 per 50 lb. bag, compared to $30 for a similar bag of sunflower seeds, this is a very expensive seed to offer birds, so it’s not something you want to see spoil.
BTW, nyjer is a small, thin, black seed from the African yellow daisy (Guizotia abyssinica), so it’s not related to the thistle plant even though it’s often casually referred to as thistle seed. Some folks see a prickly thistle plant pop up in their yard, and blame it on this seed, but I repeat, it’s not thistle.
Additionally, the nyjer seed that is sold as birdseed is sterilized by heating the seed to almost 250°F, which also sterilizes any potentially noxious and invasive plant seeds that get mixed in with the nyjer seed.
Most nyjer seed that you can purchase is grown in places like Singapore, Burma, Ethiopia, and Myanamar. It’s all hand-harvested overseas because mechanical harvesters do a poor job with such a small seed. So, add together the import/tariff costs and the labor cost, and that’s why this seed is so pricey. The other reason for the high cost is that when ethanol speculation caused corn prices to soar, many farmers switched to growing corn rather than nyjer, or sunflowers for that matter.
Some nyjer seed, an adapted variety that matures at an earlier date, is grown in the U.S., but really very little.
High in oil, nyjer is a nutritious source of energy for backyard birds, but for the money, we just stick with sunflower seeds.
Great Horned Owls Nesting
Great horned owls are currently engaging in peak courtship, hooting back-and-forth in preparation for mating and laying eggs. In Wisconsin, territorial hooting ends generally by mid-February in keeping with the timing of first eggs being laid anywhere from late January in the southern counties to mid-March in the North Country.
The female lays one to four eggs, but most commonly two, and she does all the incubating, maintaining her eggs at an incubating temperature near 98°F, even when the ambient temperature is more than 70° colder.
The male isn’t a total loss – he continually delivers prey to her through the night.
The eggs are incubated for a month or so, then the chicks hatch out naked with their eyes closed. They grow incredibly fast – in one study, the three young gained an average of over an ounce a day during the first four weeks after hatching. That may not sound like much, but adult great horned owls only weigh 2 to 5 pounds, the female usually weighing a pound heavier than the male.
If food is in short supply, the youngest and weakest may be killed by the older, larger sibling, which always makes me less critical of the way my older brother treated me.
Is it necessary for great horned owls to nest so much earlier than other birds? Yes. Unlike robins, which incubate eggs for 12 days and fledge their young in two weeks, great horned owls watch over their owlets for months. Six weeks after hatching, the young birds test their wings, but only after twelve weeks will the owlets fly. Even after fledging, they are still fed by their parents well into July.
Great Backyard Bird Count
The Great Backyard Bird Count takes place beginning today and runs until the 21st. Anyone from across the world can participate with as little as 15 minutes of time. Participating is easy, fun to do alone or with others, and can be done anywhere you find birds.
Here’s the protocol:
1- Decide where you will watch birds.
2- Watch birds for 15 minutes or more at least once over the four days, February 18-21.
3- Count all the birds you see or hear within your planned time/location and share your bird sightings using either the free Merlin Bird ID app, the free eBird Mobile app, or the free eBird website for desktop computer.
I use the eBird website, which can hold all my data from any birding trips I’ve ever been on, or simply from any daily observations I have at our bird feeders.
In 2021, over 300,000 people from 190 countries participated, identifying 6,436 species of birds worldwide!
The largest “flock” of birds reported was a gathering of 250,000 common murres on Southeast Farallon Island near San Francisco, California. A huge flock of 200,000 red-winged blackbirds near Boone, Missouri, was the second biggest group reported in the United States. One person even witnessed a gathering of 32,500 horned larks at one location in Utah.
I don’t know how someone even begins to count numbers of birds that large. I’m hoping to see 13 or so species at our house, with the largest group likely being a flock of 30 or more redpolls.
A Couple Amazing Records on Aging
Currently, the oldest known living land animal is “Jonathon,” the Seychelles giant tortoise, who has lived for 140 years on St. Helena Island, a tiny volcanic British territory more than a thousand miles off the coast of Africa. He’s likely older, however. Jonathan, at 440 pounds and now blind, is thought to be around 190-years-old. He’s estimated to have hatched at the very latest in 1832, according to a letter that mentions he arrived as a gift “fully grown” on St. Helena in 1882 from the Seychelles Islands in the Indian Ocean. “Fully grown” for a land tortoise means at least 50 years, so he may be much older. A photograph dating from 1886 shows Jonathan four years after his arrival on Saint Helena. Measurements taken from the photograph show that he was definitely fully mature in 1886.
And then there’s this story on old fish: Research in a set of unique Canadian lakes is backing up an evolutionary theory often predicted but never before shown that given the right circumstances, fish get old – decades old – but they don't age.
Scientists have been working for over 50 years on Ontario’s Experimental Lakes Area, a series of isolated watersheds in far northwestern Ontario, that were set aside in 1968 as an open-air biological laboratory, yielding uniquely detailed long-term data sets. They’ve been catching the same individual fish there for decades, and what they’ve found in lake trout is that fish get old – decades old – but they don't age. Getting old doesn’t seem to faze lake trout. In fact, it appears to make them stronger. Lake trout don't stop growing as they mature, meaning an older adult will be larger and more reproductively capable than a young adult.
In the bottom of these deep lakes, there are basically no predators that can eat an adult lake trout. The researchers write, “Theory predicts aging should be minimal in species where they increase their reproductive potential as they get older because they get bigger, and they decrease their likelihood of predation as they get older, because they get bigger . . . What we found does pretty much what theory predicts.”
In fact, said one of the researchers, the theory goes one better. At a certain point, fish should – in a sense – get younger. “We think if you sampled other lake trout populations where they continue to grow to enormous sizes, there should be signs of negative aging.”
The bottom line they say? Age, or what people might call aging, is not inevitable in all species.
Saw-whet Owl
On a sad note, we found a dead saw-whet owl in our yard on 2/11. We’ve heard saw-whets nearly every spring that we’ve lived here in Manitowish, now 38 years, but we’ve never seen one. Finally seeing one, but only after it had died, makes it doubly sad.
The question I have is twofold – why did it die, and what was it still doing here in the first place? Let’s start with the second part. Most northern saw-whets migrate southward in winter, concentrating their migration routes along the Great Lakes, but range maps show that they can winter in the Northwoods. Tom Erdman, curator of the Richter Museum of Natural History in Green Bay and a long-time bird bander/researcher, wrote to me many years ago saying saw-whet owls do winter over in our area, as evidenced by dead saw-whets that have been turned in to him during a winter from Minocqua and Lakewood. Male saw-whets migrate first, beginning at the end of February, while females follow beginning in mid-March. So, most likely this was a saw-whet that remained the winter, given that their migration should not have begun this early in February.
So, why did it die? The two most likely possibilities are that it starved or it hit something solid (a wall, a tree?) while trying to capture prey at night. Unfortunately, I didn’t find the owl – our new Australian shepherd puppy did – and by the time I noticed her with this brown bundle in her mouth, the owl was pretty gummed up. She was mouthing it up next to our house and not far from one of our bird feeders, so perhaps it was unsuccessfully hunting the feeder for mice who come out at night to eat the seeds. It’s all speculation, of course.
I called Bruce Bacon, a friend and master bird bander who I mentioned earlier in the column, to come over and give me his thoughts on how it might have died. Feeling the fat on the bird’s keel, he thought it had recently died, hadn’t starved, and likely hit something.
Celestial Events
Sixty years ago, John Glenn was the first American to orbit the Earth on Feb. 20, 1962.
We hit 11 hours of sunlight on 2/27 (only three weeks now until spring equinox!).
On 2/28, look after dusk for Saturn about four degrees above the waning crescent moon.
The first few days of March mark the first time our average high temperatures reach 32° since back in late November. Minocqua averages 269 days with high temperatures above freezing (74%).
The new moon occurs on 3/2.
For planet watching in March, there’s no action after dusk, so you have to get up early instead. Look before dawn for Venus low in the southeast, Mars also low in the southeast, and Saturn, which rises right at dawn, in the east-southeast.
Thought for the Week
In the depths of winter, I finally learned that within me there lay an invincible summer. – Rainer Maria Rilke
No comments:
Post a Comment