A Northwoods Almanac for 9/19 – 10/2, 2014
Bob Klauer in Presque Isle Township sent me a photo of a pair of albino squirrels taken on their property in Presque Isle Township.
Valerie Kuechler in Arbor Vitae sent me some pictures of deer and sandhill cranes socializing in her front yard in early August. She noted, “I was totally amazed when the deer came up while the sandhill cranes were here, and they all just hung out together.”
Jack Washow read my comments in in my last column regarding turkey vultures on Lake Pokegama and added to the story: “We live on Pokegama Lake and have observed on a nightly basis a roosting spot on the lake of usually 40 or so turkey vultures for the past five years. They usually start to ride the thermals between 5 to 6 PM, and you can spot them all over the lake. The trees where they roost are starting to die out, not unlike blue heron rookeries. Numbers were down somewhat this year; no idea why. I wouldn't think the late ice would be an influence. They definitely have become an ‘abundant’ species here.”
Our first frost of the fall in Manitowish finally occurred on 9/15. The bad news is that our tomatoes and peppers never ripened, but that used to be normal for our garden - when we first moved here, we consistently had frost around 8/20. The good news is that the mosquitoes should have suffered a major hit. We took hikes early this week with only a few mosquitoes to bother us, and what a pleasure that was! It’s been a very tough year with mosquitoes.
Ruby-throated hummingbirds have departed, most in the first week of September it seemed. We’re still leaving our feeders out until the end of the month in case a slowpoke or two may be migrating through.
Hummingbirds are carnivores (nectar is just quick fuel to power their flycatching activity), and they depend on insects. So, they must retreat back "home" to Central America or risk starvation, though a few ruby-throats remain along the Gulf coast each winter. There also is evidence that fewer ruby-throats cross the Gulf in fall than in spring, most instead following the Texas coast back into Mexico.
Ron and Skippy Winter in Boulder Junction are trying to help deter the population decline of monarch butterflies. Ron believes that the main problem for monarchs in our area is predation, not by vertebrates (birds, mice, etc.), but by invertebrates – ants, spiders, flies, and a specialized form of parasite called parasitoids, which are insects that consume the caterpillar from the inside out. Ron says, “In the 18 years I've lived here, I have never found a chrysalis in my milkweed patch, so there is something going on.”
In order to help rebuild the population, Ron described how they raise monarchs: “We collect the eggs and caterpillars from milkweed, place them on milkweed leaves with the stems immersed in water in glass jars, which are placed in five gallon buckets with wire screen covering the buckets, wire of 1/8" mesh or smaller. This summer we had five buckets going. They must be supplied with fresh milkweed leaves every day, because they eat a lot. When the caterpillars are mature, they crawl up and attach to the screen, hang in a J for a few hours, do a quick jiggle to escape their skin, and form a chrysalis. After about 10 days, the mature butterfly emerges (a fascinating and quick process of a few seconds), and in a few hours the ‘paint is dry and the gas tank is full,’ and we place them on the milkweed plants or flowers.
“This summer we reared and released 43 butterflies. The attached photo is just one morning's production.”
Great Cone Year
White pines are having a banner year producing cones, as are white spruces. What is absolutely remarkable about this production is that it’s not just local – it occurs over a vast region. Researchers have found that conifers at sites as far as 1,500 miles apart synchronize their seed production. As difficult as that is to believe, trees are thus synchronizing their reproductive activities over an area of at least three million square miles!
The process is called “mast seeding,” and ecologists have hypothesized that it occurs because synchronous reproduction greatly increases reproductive success. The boom and bust cycle of seeds available to predators imposes alternating and varying starvation-satiation regimes which help ensure that when huge numbers of seeds are produced, plenty of them go uneaten.
Predator satiation is an example of “economy of scale.” The idea is that large seed crops are more efficient than small crops because each seed has a higher probability of escaping predation. Thus, it’s more economical for the tree to produce an occasional bumper crop over the long run than to produce the same size crop each year, even though in the other years it produces few or no seeds that survive.
Additionally, masting likely enhances pollination efficiency. Plants that synchronously produce masses of flowers and pollen once every few years are likely to experience higher pollination rates than plants that produce average amounts of flowers and pollen each year.
The benefits of having one binge year so outweigh the costs that masting species more or less forgo reproduction entirely in non-masting years.
Synchronous mast seeding is common in plant populations, but how the masting trees apparently come to a consensus when to produce a bountiful crop is still open to debate. How do trees synchronize their flowering? It is one thing for trees to produce more seeds some years than others, but how do they manage to coordinate their activities?
Weather appears to be the major cue for mast fruiting. The synchronization of populations due to environmental fluctuations is termed the “Moran effect,” from work in the 1950s by Patrick Moran, an Australian statistician. Moran showed that an external factor, such as weather, that acts across separated populations of a species will tend to produce correlated changes in their abundance, and hence synchronize their population cycles.
The bottom line is this – trees appear to use fluctuations in temperature as the cue for whether to invest their resources in growth or in reproduction in any given year. This spring’s cold temperatures must have created a Moran effect. One way or another, it’s squirrel heaven out there, and they’re already snipping cones and storing the seeds for winter.
Hawk Migration Is On!
We’ll be up on Hawk Ridge this weekend hoping to catch the wind coming out of the west or north, and thus funneling what we hope to be thousands of hawks our way. The forecast looks to be just the opposite of what we need, unfortunately, but Duluth is notorious for being in its own meteorological world, so perhaps we’ll get lucky.
In the meantime, the weather early this week was near perfect, and the hawks have been active. On 9/11, the count was 2389. On 9/12, 4281 raptors flew past. And on 9/13, 2102 were seen.
Broad-winged hawks are the showstopper right now and account for over four-fifths of all the raptors seen, with sharp-shinned hawks contributing another 10 percent or so every day. When the winds aren’t quite right for the thermal-gliding flight of the broadwings, the sharpshins become the star attraction because they can use a powered flight, flapping as needed to push through less than ideal winds.
Raptors aren’t the only birds flying over the ridge. The peak day for the non-raptor migration so far was 9/9 when 8603 birds passed by, including 2066 Canada geese and 4102 blue jays. On 9/11, 6277 migrating non-raptors also cruised by, including 226 Canada geese, 112 sandhill cranes, 4732 blue jays, 637 cedar waxwings, and 321 common grackles.
The day before, 9/10, was the peak day for cedar waxwings, with 1115 counted.
The peak warbler day was a bit earlier, on 9/6, when the counters were able to identify and individually count 16 species of warblers, along with 1675 unidentified warblers. How they identify any of them while they’re flying by is very impressive.
In the eastern predawn sky on 9/19, look for Jupiter below and to the left of the waning crescent moon. On 9/20, Jupiter will be suspended just above the moon. Simply look eastward near the horizon.
Autumn equinox occurs on September 22nd this year. Because the Earth is tilted on its axis by 23-and-a-half degrees, Earth’s Northern and Southern Hemispheres trade places twice a year – spring and fall – when the tilt of the Earth’s axis and Earth’s orbit combine so that the axis is inclined neither away from nor toward the sun. On this day, Earth’s two hemispheres are receiving the sun’s rays equally, and night and day are approximately equal in length. This is a good day for finding due east and due west from your yard – just go outside around sunset or sunrise and notice the location of the sun on the horizon with respect to familiar landmarks.
On 9/27, look in the southwest after dusk for Saturn which will be just east of the waxing crescent moon. The next night, 9/28, the moon will shine between Saturn to its west and Mars to its east.
Mushroom of the Week
We found on 9/15 a mushroom we’d never seen before – toothed jelly. You have to like a mushroom that is translucent white, tiny, and feels gelatinous. Very cool.