Welcome to Fall Migration

There is an abundance of “welcoming” habitat at Goose Pond for the fall migration.  Today, there are 660 monarchs still roosting in spruce trees and one white pine in the yard at the Kampen Road residence.  The monarchs are nectaring on large patches of the colorful purple New England aster and showy goldenrod flowers.

Monarchs on New England aster, photo by Monica Hall

Grassland birds can still be seen fliting around in the prairie or in the shrubs including silky dogwood.  Sedge wrens, common yellowthroats, and a few eastern meadowlarks along with warblers are with us now.

Sedge wren, photo by Arlene Koziol

Water levels are at a record high for this time of the year.  Usually the shallow wetlands are dry with much of the area planted to corn or soybeans. However, this year instead of seven-foot high corn plants there is a diversity of emergent vegetation including water plantain, smartweeds, barnyard grass, bidens, softstem bulrush, cattails, and the first wild rice plant seen at Goose Pond.  Many of the emergent plants, especially those in bold above are providing an abundance of high energy food for migrating ducks.  Goose Pond is about seven-feet deep and most of the wetland birds are feeding in the 100 acres of shallow wetlands on Audubon property and adjacent landowners.

The southern shorebird migration began in July and there are still flocks of migrating shorebirds including yellowlegs.  The shorebirds love the mud flats where they are busy searching for invertebrates.

Great egret, photo by Monica Hall

Fish eating birds, including great egrets and double crested cormorants are feasting on abundance of fat head minnows.  It has been reported that female fat head minnows can spawn every week when the water temperature is between 64 to 85 degrees.  Goose Pond may contain hundreds of thousands of minnows.  The downside to having minnows in the pond is that they also feed on invertebrates, frog, and salamander eggs.  Ducklings need an abundance of invertebrates to feed on.  

The record number of 95 great egrets has declined however over 20 egrets and great blue herons can still be photographed as they fish. Arlene Koziol photographed an osprey on the causeway.  We assume the osprey would rather feed on large fish and quickly moved south.

Other raptors observed recently include northern harriers, American kestrels, a peregrine falcon and a record number of five bald eagles seen by Arlene Koziol.  The peregrine is probably looking for shorebirds and ducks and was last seen in the tree on the Goose Pond Road causeway.

Bald eagle, photo by Monica Hall

The pair of bald eagles whose nest is about three miles north of Goose Pond are frequent visitors.  It is not hard to tell when eagles are present as they flush egrets and ducks.  Sue was rewarded by seeing the flock of 95 great egrets overhead after they were flushed by the eagle.  Recently Mark and Graham observed two flocks of 30 blue-winged teal in the open water and then spotted the bald eagle.

The last of the migrating bobolinks will be moving south shortly after feeding on smartweed seeds and seed in our sorghum and sunflower food plot.  Red-wing blackbirds, mourning doves, and American goldfinch numbers are increasing in the food plot.

Pied-billed grebe, photo by Arlene Koziol

There are over 30 pied billed grebes present and they will remain for a couple of weeks.  Canada geese, ducks, and American coot numbers will be increasing.  

We welcome you to come out and enjoy the habitats and birds.  You can visit the Wingspan viewing area on Prairie Lane or enjoy the views from the benches and newly landscaped area along Prairie Lane adjacent to the spotting scope, or hike the trails, especially the trails that begins at the Browne Prairie parking.  

Come take a seat at the beautiful south edge of Goose Pond. Photo by Arlene Koziol

Written by Mark Martin and Susan Foote-Martin, Goose Pond Sanctuary resident managers

Chestnut-sided Warbler

Photo by Jeff Bryant

The chestnut-sided warbler, decorated as it is with chestnut-streaked flanks, almost resembles an oak leaf. Indeed, in southern Wisconsin the breast of a chestnut-sided warbler could very well extend from a cured black oak leaf—a potential spot for finding this warbler during the breeding season.

I love the appearance of a chestnut-sided warbler: with its yellow cap it declares its warbler-ness while its messy chestnut streak resembles spilled coffee down its side. Likewise endearing is its call—the mnemonic I've come up with is “choo choo choo god-bless-you!” Unlike the eastern towhee which admonishes you to “drink your tea,” or the yellow warbler (which can have a confusingly similar song) in its braggadocios endowment of itself as “sweet, sweet, sweeter than sweet,” the chestnut-sided warbler sneezes and humbly excuses itself.  

There's more to that song than the trivial way a human remembers it, however. Ending the chestnut-sided's song is either an accented or unaccented syllable. When the accent is used, the male is attempting to attract a mate, while the unaccented song is employed for territory defense when other males are around. So, we have some idea of the language of the chestnut-sided warbler: if he's on a nest, you might expect to hear the territorial song (unaccented) while his accented ending may mean he's still looking for a mate.

Photo by Arlene Koziol

Further research into chestnut-sided warbler song has revealed that certain songs are associated with greater reproductive success. It turns out, in chestnut-sided warblers, high-pitched and steady wins the race. Males who sing with a high and steady pitch and consistent timing are more likely to have a successful breeding season. If you hear a chestnut-sided warbler in the woods that's mapping new vocal territory with each song, it's not as likely that a female will choose this variable warbler.

When I've encountered chestnut-sided warblers it's been in oak barrens areas in northeastern Wisconsin, where the bird is common north of Marathon County. It's uncommon in central Wisconsin, and a rare breeder in southern Wisconsin where I've seen it in regenerating oak scrub in the southern Kettle Moraine. While this bird's preferred habitat is rather rare in Wisconsin (oak savanna and barrens), the advent of large-scale logging operations proved a great benefit to chestnut-sided warbler populations. These birds will readily occupy cut-over land, and as such they have a secure population in northern Wisconsin.

Written by Drew Harry, Faville Grove Sanctuary land steward

Banner photo by Arlene Koziol

Common Loon

One of the most iconic species of summer in the northern forest, the common loon beckons admiration, from wooden carvings, gift shop trinkets, ring tones, and paintings. For those spending a vacation around a campfire in northern Wisconsin, loons lay the soundtrack in equal parts to the campfire.

In fact, I think the distribution of common loon breeding in northern Wisconsin is a good approximation for the southern limits of “up north.”

Rough approximation of “up north” based on common loon breeding range in Wisconsin. Image courtesy of eBird

The Journal Sentinel has developed a map where you can draw your own line for where “up north” is located; most agree, it follows a line a little north of Green Bay west to about Chippewa Falls.

Over the course of the year, loons will move through southern Wisconsin, typically occupying larger bodies of water along the way. Lake Mendota in Madison and Rock Lake in Lake Mills are two excellent spots to view the common loon right now as it migrates through the area.

Colorful common loon on Lake Monona, April 4, 2019. Photo by Pat Ready

Lake Monona loon, april 4, 2019. Photo by Pat Ready

During migration, loons with tracking devices have been recorded on dives of 174 feet.  If you see any loons on Lake Mendota this spring, imagine the deep hole between Picnic Point and Maple Bluff. That’s 82 feet deep, so loons can dive to depths of more than two Lake Mendota’s!

Listen to the calls of the common loon, and watch how it deftly dives and swims underwater. Video by BR Valley.

Historical accounts indicate that loons did nest in parts of southern Wisconsin. A number of factors conspired to limit the loon’s range to the northern expanse of Wisconsin, including wetland loss and degradation, mercury bioaccumulation, and lead poisoning.

Loons nest within a few feet of the water, and wetlands at the edge of lakes are critical to nesting success. A common spot for loon nests is on the floating sphagnum mat at the edge of relatively acidic lakes in northern Wisconsin. Unfortunately for loons, lakefront development can negatively impact the ability to nest.

Good habitat on a sphagnum mat, inset: no habitat. Photo courtesy of Mike Meyer, “Twenty Four Years of Common Loon Research in Wisconsin”

Researchers have found that development of housing greater than 25 buildings per kilometer of shoreline prevents loons from nesting in the area. Housing development usually leads to the degradation or elimination of wetland habitat along shorelines.  It doesn’t need to be this way. Many alternatives to a barren lawn exist that beautify the yard and add habitat for wildlife, and protect the erosion into the lake.  You can find numerous excellent examples here.

The map below is from the USDA Forest Service’s North Central Research Station and shows how housing density has increased in northern Wisconsin since 1940.

Image from Wisconsin’s Land Legacy Report

Having the pleasure of loons on your lake can come with a number of responsibilities. Known nesting sites should not be disturbed during the summer. If there are known nesting sites, efforts should be made to reduce wake in those areas. Additionally, lead fishing tackle contributes to significant mortality each season. In Minnesota, one study found that 15-20% of dead loons had lead poisoning. Using non-lead alternatives is good for loons and the whole ecosystem. One of the biggest items on Wisconsin’s Conservation Congress hearings this past week was a ban on lead tackle and ammunition. This would have positive impacts for the loon population, and it is estimated that a lead ban would save over 50 loons in Wisconsin each year.

An issue outside of a loon enthusiast’s direct control is the emission of mercury from coal-generated power plants. As stated before, loons are sensitive to the bioaccumulation of methyl mercury because they are high in the food chain, long lived, fish-eaters, and nest on acidic lakes, which tend to have higher availability of mercury to move up the food chain (pictured below).

As pH decreases (becomes more acidic) mercury concentrations increase in both adults and chicks of common loons. Graph courtesy of Mike Meyer, “Twenty Four Years of Common Loon Research in Wisconsin”

A new EPA proposal would roll back some limits on emissions of mercury for coal-burning power plants. This could have a huge effect on public health, and different accounting estimates calculate the potential indirect benefit of saving thousands of lives due to the “co-benefit” of also decreasing particulate matter linked to lung and heart disease. In Wisconsin, coal-burning power plants have been granted exceptions for mercury emissions. Beyond public health, mercury for loons spells trouble. 

As mercury increases, hatching rates decrease beyond a sustainable number. With high mercury concentrations in the food chain, adults become lethargic and might not reproduce at all. This decreases the likelihood of success for the common loon, which already faces difficult enough odds on its breeding grounds where approximately 50% of nests fail, due to predation, flooding, or other causes.

Another twist might occur as the climate continues to change. With flooding more likely, the amount of mercury in aquatic systems may also increase. Research from UW-Madison’s Center for Limnology has found an interesting correlation between annual water levels and the concentration of mercury in walleye. You can see that interesting blog post here. With flooding and high water levels, loons may be even more susceptible to mercury bioaccumulation.

While fragile, the outlook for loons in Wisconsin is rather positive. Since 1980, the population has nearly doubled and continues to increase. If you’re able to help, you can sign up for Northland College’s Loonwatch, which aids research in a number of areas.

Written by Drew Harry, Faville Grove Sanctuary land steward

Cover photo by Arlene Koziol

Sources

Stewart, S. I., Hammer, R.B., Radeloff, V.C., Dwyer, J.F., & Voss P.R. 2003. Mapping Housing Density across the North Central U.S., 1940-2000 [Slide show]. Available: http://www.ncrs.fs.fed.us/IntegratedPrograms/lc/pop/hd/title.htm

Meyer, Mike. "Twenty Four Years of Common Loon Research in Wisconsin." Microsoft PowerPoint file. Accessed here.