Forster's Tern

Female Forester’s tern. Photo by Arlene Koziol

Terns are in the same family as gulls and skimmers, and 40 tern species are found worldwide. The arctic tern migrates from Antarctica and back again over a six month period. Their journey is not necessarily in a straight line, and on average the round trip migration distance covers an unbelievable 44,000 miles. All four tern species regularly found in Wisconsin, Forster’s tern, black tern, common tern, and Caspian tern are listed as state endangered. Wisconsin DNR and other groups have developed innovative ways to assist these species, and particular progress has been made with Forster’s terns.

Numerous Forster’s terns mingle in native vegetation in a wetland. Photo by Daryl Christensen

The Forster’s tern is a colony nester. Bird colonies are usually found on sites that are well protected from the usual terrestrial predators. Because colony nesting birds only congregate for a small portion of the season, local predator populations do not boom as they might with a permanent high energy food source. Forster’s terns breed in large marshes with abundant emergent vegetation, and most of the breeding population in Wisconsin inhabits the east central portion of the state or lower Green Bay.

In pre-settlement days, an estimated 10 million acres of wetlands existed in Wisconsin according to Wisconsin DNR. Around 50 percent of those acres were destroyed because of conversion to agriculture, urban area, or other uses. Some colony nesters have a remarkably high site fidelity, meaning that they return to the same breeding site year after year. Forster’s terns are more nomadic than others in this sense. They require specific water levels for optimal nest success; plenty of water to maintain prey populations and deter predators, but not so much that their source of cover is below the water line. Historically Forster’s terns had many more options when choosing a colony site. Greater habitat choice led to more successful nests and higher populations.

A Forster’s tern on a nest platform, Photo taken by Daryl Christensen in 1983 or 1984

Because of low nest success and declining populations, the Wisconsin DNR began deploying nesting platforms for Forster’s terns in 1983. Nest platforms provide high quality nesting sites when natural substrates are of low quality or in short supply. After eggs are laid, rising water can easily submerge nests. Fluctuation in marsh water levels is likely exacerbated by hard surfaces and row crop cultivation due to their low water infiltration potential. Nesting platforms float on the water surface. They are attached loosely to a pole which allows them to rise and fall in response to changing water levels.

Nesting platforms significantly increase nest success, and 100 percent of deployed platforms were utilized by terns in 2018. This year at Lake Puckaway, 200 breeding pairs produced 259 eggs without the assistance of platforms. At Grand River Marsh, 19 breeding pairs that were occupying tern platforms produced 58 eggs. This means that breeding pairs of Forster’s terns were able to produce over two times the eggs using platforms than on natural substrate. Lake Puckaway flooded after this nest survey was completed, and all eggs were lost. Forster’s terns do renest, but their egg production decreases after each nesting attempt.

The Wisconsin DNR plans to increase the number of tern platforms to 150. Ryan Zabs, a Sun Prairie Eagle Scout, reached out to Goose Pond Sanctuary in search of his final Eagle Scout project. He helped us take a huge step towards those 150 by building 50 platforms in a single weekend. Sumner Matteson with Natural Heritage Conservation Bureau at WIDNR generously provided funding for the platform materials.

Forster’s tern nest platform, photo by Daryl Christensen

While the success of tern platforms certainly is exciting, it must be noted that this is not a permanent solution. Continued restoration of large wetlands and further protection of coastal wintering grounds is the best hope to keep Forster’s terns on the Wisconsin landscape now and far into the future.

Written by Graham Steinhauer, Goose Pond Sanctuary land steward

Brown Creeper

The brown creeper, more evident now than perhaps at any time in its life cycle, remains a cryptic bird even as bird density has thinned considerably due to migration south. When threatened, brown creepers stay incredibly still, and their perfectly camouflaged plumage so matches the bark of trees that a still brown creeper can easily be mistaken for a leaf or peculiarity of the bark.

Photo by Mick Thompson, FCC

The secrets of the brown creeper intensify during its breeding season. Preferring bottomland forests of silver maple and elm, it is possible to find breeding birds in southern Wisconsin, though unlikely. In Wisconsin’s second Breeding Bird Atlas, Jefferson County only recorded one breeding pair, along the forested bottomlands of the Rock River as it enters Lake Koshkonong. Other breeding records in southern Wisconsin are rare, with scant records in lowland forests and bottomlands.

Brown creeper nest building. Photo by Don Henise, FCC

Brown creepers construct nests in a unique way; they layer cocoons and spider egg cases together with twigs and strips of bark, and almost all records have the placement of the nest behind a strip of bark hanging off a tree. Because of this habit, creepers need forests with old growth characteristics, with plenty of standing dead wood to provide excellent foraging and nesting opportunities. In fact, in western US forests, brown creepers are considered an indicator species of old growth forest because they prefer a dense upper canopy and tall trees—almost 50% taller at occupied versus unoccupied sites.

Using their long bills to pry away strands of bark is a favorite activity of creepers, and their process of foraging involves starting at the base of the tree and moving upward, then diving to the bottom of the next tree.

Some research suggests that brown creepers exhibit habitat partitioning with co-occurring birds like nuthatches. Creepers will forage lower on trees and on thicker branches while nuthatches prefer slimmer branches and higher points of the tree. However, in areas where forest has been fragmented or logged, the brown creeper has been shown to be in competition with these other species. Thus, large blocks of forest with large diameter trees are important to both overwintering and breeding grounds.

Photo by Claudine Lamothe, FCC

You can find brown creepers throughout Faville Grove Sanctuary, wherever there are good-sized trees. It’s rather rare that they use their high-pitched call during winter, so you’ll have to methodically scan trees in order to uncover this secretive species. Brown creepers will also frequent residential areas, again where large trees occur, so you might see them around your backyard.

Written by Drew Harry, Faville Grove Sanctuary land steward

Cover photo by Carolyn Lehrke, FCC

House Finch

Recently we observed a house finch at our bird feeder with puffy red eyes. Something was clearly wrong. This distressed individual prompted us to learn more about these urban birds and their reputation for contracting eye diseases.

Before the house finch range expanded to southern Wisconsin in the 1980’s and 90’s, it was easy to identify purple finches. While they do appear similar, a side by side comparison helps immensely with differentiating the two species. Purple finch males have a striking purple head, a larger bill, and wing feathers that are edged in red.

House (left) and purple finch (right). Photo by National Audubon Society

House finches are native west of the Rocky Mountains. In the 1940’s and 50’s, many Americans achieved a standard of living that allowed them to buy pets. Wild house finches, marketed as Hollywood finches, were trapped illegally in southern California and shipped to Long Island, New York. A birder recognized house finches in a Long Island pet store, and reported the situation to the Audubon Society. This news was passed to federal officials, and unscrupulous pet store owners shooed their loot of house finches into the streets to avoid prosecution.

Stan Temple, in 2006, wrote the house finch section in the Atlas of Breeding Birds of Wisconsin, “This remarkable range expansion has to be regarded as one of the more significant ornithological phenomena of recent decades.” In Wisconsin there were a few sightings in the 1970s. By 1986 they were added to the Wisconsin bird list. We found our first house finches in 1990 on the Poynette Christmas Bird Count. Researchers estimate that there are around 34 million house finches in the U.S. Temple mentions one reason for their explosive population increase is that birds can nest from late March to early September, and that most pairs raise two to three broods with four to five young.

Range expansion of the house finch. Image by Cornell Lab of Ornithology

In Breeding Bird Atlas I from 1995-2000, house finches were found in 61% of the priority blocks, and at the end of year four in Atlas II they have been found in only 29% of priority blocks. It appears that their range has increased in some areas, however it recedes in others, and they are still uncommon in forested areas of northern Wisconsin.

Populations of house finches suffered a steep decline beginning in January 1994 as a result of a contagious disease called mycoplasmal conjunctivitis. The disease causes respiratory problems and red swollen eyes, making them susceptible to predators and adverse weather. Luckily it’s not harmful to humans. The disease is easily spread by birds feeding at tube feeders that offer Nyjer and hulled sunflower seeds.

This house finch suffers from conjunctivitis. Photo by Fyn Kynd

House Finch conjunctivitis was first observed at feeders in the Washington, D.C. area. Temple stated that conjunctivitis spread through the population as rapidly as the population spread through the eastern U.S.

So what is a bird feeding enthusiast to do? We want to feed birds for a variety of reasons, but we do not want to spread disease to birds who share our feeders. A call to Pat Ready, MAS member and volunteer provided the answer to the problem. Wild Birds Unlimited offers their “Eco-Clean” line of tube feeders which feature a product called Agion. We have now purchased these feeders to replace all of our old tube feeders. The feeders are coated with Agion which starves bacteria of oxygen and inhibits bacterial reproduction. The feeders are costly, but we want to maintain a healthy bird feeding community, not one that spreads disease to our flock. Wild Birds Unlimited is the only place where EcoClean feeders are sold.

House finches and American goldfinches are feeding on an Eco-clean feeder stocked with sunflower medium chips at Goose Pond Sanctuary. Photo by Mark Martin

We enjoy watching the house finches at our feeders, listening to their songs, and observing them nest around our residences in hanging flower baskets.

Written by Mark Martin and Susan Foote-Martin, Goose Pond Sanctuary resident co-managers, and Graham Steinhauer, Goose Pond Sanctuary land steward

Black-capped Chickadee

The black-capped chickadee is one of the most common birds in the northern United States, and one of the most extraordinary. Not to say other birds are less extraordinary, rather their capabilities have not been realized to the degree with which we have studied the black-capped chickadee. Case in point: a 362-page book on the species, The Black-Capped Chickadee: Behavioral Ecology and Natural History.

Photo by Kelly Colgan Azar

Most impressive, perhaps, are studies of black-capped chickadee songs and calls that have uncovered a vast treasure of meaning. With over 16 different vocalizations, chickadees can communicate a wide variety of information. For instance, the “fee-bee” call indicates a male’s territory and attracts mates. That familiar “chick-a-dee” song conveys a number of messages to wintering flocks of chickadees; the number of “dees” at the end is associated with the threat of the predator. Smaller raptors like cooper’s hawks and kestrels register more “dees” than a red-tailed hawk or great horned owl. Research has also shown that the chickadees are responding to cues of bird size and even species; when bobwhite quail were placed with chickadees, no alarm calls were made.

Thus, a single call (“chick-a-dee”) not only indicates a threat, but it indicates a threat to a certain degree. While this alarm call obviously alerts flocks of chickadees to predators, it also calls to action nearby birds of the mixed flock. Nuthatches, woodpeckers, kinglets, and creepers will respond to these calls and mob predators.

Photo by Mick Thompson

Black-capped chickadees overwinter in Wisconsin, and for such a small bird to survive the cold turn of the seasons, it has to develop remarkable adaptations. While the summer diet of black-capped chickadees consists almost entirely of insects, and mostly caterpillars (you can help chickadees with those caterpillars, according to recent research, by planting mostly native plant species), winter chickadees feed on about 50% plant matter. In order to prolong certain available foods items, chickadees cache food in crevices and cavities in trees. Over the course of fall and winter, chickadees will cache and retrieve thousands of food items.

In one study, black-capped chickadees retrieved preferred food items over non-preferred types. This same study found chickadees to have episodic memory, able to discriminate using both time of day and elapsed time to determine where the freshest mealworms were located. These are remarkable findings of such a small, often overlooked bird.

Photo by Mick Thompson

Adding onto these studies, further research has proven an expansion of the hippocampus, important for spatial organization and memory, in black-capped chickadee during fall and winter, increasing volume of the hippocampus up to 30%. By caching an extraordinary number of food items, these chickadees achieve brain growth during adulthood, a unique and resourceful adaptation.

I envy the plasticity of the black-capped chickadee, for fall seed collecting at Faville Grove might become much easier with a hippocampus a third larger than my spring and summer brain. I value the chickadee for its soulful winter song, a cheery and longing embrace of December. You can find chickadees throughout wooded areas of Faville Grove Sanctuary this winter. When you observe these birds, try to recall all of these amazing facts about the black-capped chickadee, and realize that the chickadees you are watching might be retrieving, from a catalog of thousands of seeds, a specific dogwood berry, which will provide the bird with just the right fat content to survive the coming cold front.

Written by Drew Harry, Faville Grove Sanctuary land steward

Fall Waterfowl Migration

As the September sun falls to the horizon, vulnerable duck broods stash themselves into protected knots of emergent vegetation and only the most determined frogs continue to call at the tail end of their breeding season. Summer draws to a close, and arrowhead leaves that cover the pond during the warm season begin to senesce and reveal that there is indeed a large body of water at Goose Pond Sanctuary.

Many of us who are accustomed to seasonal changes notice small transition events. Maple leaves redden at their margins and veins. The first Canada geese return from their molting grounds on Hudson Bay. Morning air becomes crisp. If humans that spend most of their lives indoors can sense these subtleties, imagine the complex signs that wild creatures detect. Their very existence revolves around the seasons.

Blue-winged teal. Photo by Richard Armstrong

Blue-winged teal are first to leave the north. They nest at Goose Pond, and blue wing migrants show up here in August and September accompanied by the first wave of hasty mallards. These small dabbling ducks move toward their wintering grounds in Central and South America by early October. Wood ducks appear as the blue wings leave, and then a multitude of species arrive.

Throughout the month of October and into November, 3,500 ducks from fourteen species used Goose Pond. Mallard numbers increase until a swirling tornado of them can be seen several times a day over the pond and surrounding picked cornfields. Vast flocks undulate like a mirage in the distance. Some uncommon species of  note that were sighted this year include the American black duck, northern pintail, redhead, and white fronted goose. Many birds departed on the nights of November 7 and 8 because they understood something that I could never have predicted without modern technology. Much of Goose Pond froze on November 10 when temperatures plummeted to 18 ˚F.

While mostly mallards and Canada geese remained after this cold spell, tundra swans increased on the pond as they migrated out of North Dakota and from the frigid arctic before that. Three species?? That doesn’t sound very impressive. Let’s look at the numbers. Peak counts include 3,000 mallards, 960 Canada geese, 818 tundra swans, and 12 trumpeter swans. 2,500 mallards and 2,500 Canada geese were seen in the air or on Goose Pond daily throughout October and November. One “use day” is each day that an individual uses a habitat. We estimate that from October 1 through November 29, there were 8,000 swan use days. To look at this from a yearly perspective, the pond provides habitat for 22 swans every single day. This statistic doesn’t include spring migration. High bird counts attracted healthy numbers of human observers as well, some of whom had unique experiences.  

Near the corner of County Highway K and WIBU Road on Thanksgiving morning, we noticed a small flock of 35 tundra swans feeding in a harvested corn field. About 75 yards away from them, a coyote loped across the field staying parallel to them and looking disinterested. Most of the swans took off and circled back as he kept going. We followed the coyote until he disappeared into a dip in the field. We stopped to see where he went, and he had doubled back across the field even closer to the swans.  

-Arlys Caslavka

Last week I spent several hours a day for three days observing Swans and the [at times] clouds of Mallards at Goose Pond Sanctuary.  Late afternoon hours were the best as they flew back and forth to a cut cornfield to the south. I parked at the kiosk and facing a stiff wind, Swans were barely 10 yards above me.  Occasionally the unmistakable calls of Trumpeters could be heard amidst the Tundras. At late evening and sunset the colors of the the sky reflected on the white birds giving them shades of pastel pinks and oranges. I was sorry to have to leave.  At dark most of the swans were back in the sanctuary.

-Terrill Knaack

People often ask why Goose Pond attracts such immense waterfowl numbers. There are several explanations that make sense to me, but none, even in combination, are wholly satisfying. Maybe food is reason enough. Abundant carbohydrates are crucial for migration, and corn grown on rich soil of the Arlington Prairie is a primary food source for many species. Swans tip in Goose Pond to feed on energy rich arrowhead tubers with black paddles waving in the air to maintain balance. Perhaps a ban on hunting is responsible. Hunters occasionally try their luck waterfowl hunting on East Pond (water body to the east of Goose Pond Road causeway). Not a single bird will remain on East Pond while thousands splash around noisily on Goose Pond despite that both bodies are similar in size, cover, and food sources, and they are 30 feet apart. A more romantic notion is that birds have used the pond as a migration stopover for generations, and they visit more for nostalgia than necessity. If anyone has additional theories, I’d love to hear them.

Tundra swans (Cygnus columbianus) in flight. Photo by Terrill Knaack

Geese return at sunset from nearby fields in massive flocks, and they float almost straight down in an attempt to claim some real estate among thousands of birds on a half acre of open water. None of these birds seem to sleep. Hen mallards blare feed chuckles, hail calls, and the obvious quack! Swans whistle and trumpet to each other. Despite below freezing temperatures, Goose Pond retains an open patch due to the sheer number of birds. One night soon as the sky clears of clouds, winter will show itself. Waterfowl must leave when the pond snaps shut, and local populations fall to zero. They will be replaced by a startling type of silence that occurs only after losing thousands of perplexing and charismatic neighbors.

Graham Steinhauer, Goose Pond Sanctuary land steward