Northern Shrike

One of the most striking birds of winter resides on the shrubby grasslands and savannas of southern Wisconsin. In this habitat, you can find wild plum, hawthorn, black locust, or barbed wire. The common link is spikes, thorns, or barbs. In winter in Wisconsin, if you search these spiny spots, the unsettling link might be impaled microtine voles. The uninitiated might look to the sky, wondering if a hawk dropped its prey randomly onto a plum bush. The answer comes from the sky, though not from a raptor species dropping the vole. Instead, you are on the wintering range of the northern shrike, a passerine, or songbird, (the only passerine in Wisconsin to regularly eat vertebrates) which actively stuck the vole in its place. The purpose of this act is to consume prey efficiently over the course of the winter. At any point, a northern shrike will cache, or save, up to seven prey items.

An impaled vole is cached for a northern shrike’s next meal. Photo by Drew Harry

Impaled voles, mice, and other small mammals are common indicators that you are on shrike territory, which can range from 500-1,000 acres over winter. Another interesting prey item are species of its own order—songbirds! Shrikes will consume birds like horned larks, dark-eyed juncos, house sparrows, American robins, red-winged blackbirds, pine grosbeaks, and red crossbills. Many of these birds are much bigger or quicker than the shrike, and thus shrikes will take other birds in surprise attacks. In a twisted move, shrikes will even mimic the calls of other songbirds to lure them into area where they ambush an unsuspecting sparrow.

In February, I often start getting concerned about the house sparrows looming around bluebird boxes around my house, although this year they have been noticeably absent. The reason might be a shrike that I’ve spotted a few times around the house. Shrikes typically sit for 1-2 minutes on the tops of trees, perched, and waiting to strike. A week ago, I was able to get some decent pictures through my window of an immature northern shrike as it moved from bur oak tree to pear tree and again back to the bur oak trees scattered about the yard; each time sitting for 1-2 minutes and allowing me to capture a few shots.

A northern shrike is spotted at the top of this oak tree at Faville Grove Sanctuary. Photo by Drew Harry

A northern shrike scouts the landscape to make its next move. Photo by Drew Harry

A northern shrike sits perched on the tip-top of a tree, giving nearby humans a minute to get a good look. Photo by Drew Harry

The immature shrike shows gray barring on its chest, a white eye-ring, and like adult shrikes has a light underside with a blue-gray top and a narrow black mask across its eye. The hooked bill is also diagnostic.

Barring, eye ring, and mask are all visible in this shot of a northern shrike. Photo by Drew Harry

For me, the most fascinating part about the northern shrike is its winter diet. While impaled small mammals steal the show, over 60% of an individual bird’s winter diet is composed of arthropods. A study in Idaho analyzed the regurgitated pellets of northern shrikes and found an average of 2.8 prey items per pellet. Overall, 33 species were identified in pellets for a wide and diverse sampling of food. To follow a shrike in winter is to understand the surprising breadth of prey items active through winter.

You might ask, aren’t arthropods dormant during winter? For the most part, yes. However, many species will stay active, and on slightly warmer days the south-facing slopes, rock outcrops, or other exposed areas can heat more quickly than other areas and cause some invertebrates to become active. In southwestern Idaho, rimrock areas are preferred by shrikes presumably due to the higher arthropod activity on these exposed rock areas.

Faville Grove has exposed rock—1.8 billion year old quartzite—perhaps a source of arthropods for the local shrike? Each winter we often see a shrike in the western part of the Sanctuary, hanging out in the tops of tamarack trees in the Diedrich-Alexander Wildlife Area along North Shore Road. You might find a shrike anywhere within Faville Grove Sanctuary, but your best bet is to keep looking at the tops of trees, or look for indirect evidence on spiny trees and bushes.

Written by Drew Harry, Faville Grove Sanctuary land steward

Cover photo by Eric Ellingson

American Redstart

Song sparrow with bands. Photo by David Craig

In his essay “Natural History, Forgotten Science” Aldo Leopold lauds the pioneering citizen science work of banding song sparrows. The woman who decided to put these cellulose anklets on the birds, he says, “knew more about sparrow society, sparrow politics, sparrow economics, and sparrow psychology than anyone had ever learned about any bird.”

Today, advancements in technology have allowed us to go beyond the backyard scope, on a Caribbean flight to the wintering grounds of the songbirds of North America. Tiny transmitters attached to the bird measure day length, and give an accurate estimate of where a bird might overwinter. Analysis of stable carbon isotopes in feathers and nails provides insight into not only the location a bird stayed but also the quality of the habitat, and thus the health of the bird.

American redstart, photo by Becky Matsubara

These techniques have been used in studying American redstarts, and Peter Marra and his lab group have conducted the research that has revealed the inner workings of redstart culture.

First, researchers—going off of observations in the field from Jamaica—tested whether males and females were found in different habitats on the island. Indeed, the redstarts were; females and yearling males inhabited the drier scrub on the island, adult males inhabited the wet mangrove forests.

Studies of these habitat types revealed that the mangrove forest was a steady five course meal compared to the scrub. Insect orders preferred by redstarts were much more abundant in the mangroves, and that food source was much more consistent over the wintering months, whereas the scrub saw productive spikes after rainfall but also nadirs during drought.

Mangrove forest, photo by Arlene Koziol

The question to ask was then, was the habitat preference innate to males and females, or was this the result of competition?

On their overwintering grounds in Jamaica, redstarts are quite territorial. To test the competition theory, researchers conducted a removal experiment where territorial males in the mangrove forest were taken out of that habitat. The vacated habitat was filled within days by females and yearling males. It's as if these birds saw their neighbors' mansion evicted, waited a day for good measure, then quickly occupied the space.

This finding had profound implications for how we understand bird populations. Often, density is used as a proxy for quality of habitat. Yet, in these Jamaican habitats, redstarts were densest in the lower quality scrub habitat, and those despots in the mangrove forests were excluding other birds.

Researchers next asked, if these habitats differ in quality, how do they affect the health of redstarts? During the long overwintering period, from October until April or May, females and yearling males lost mass on average, while males (and the small number of females) in the mangroves maintained or increased body mass.

American redstart, first year male, photo by Kelly Colgan Azar

There's another twist in this fascinating tale, however. Yearling males exhibit delayed plumage maturation. Adult males have glossy black feathers with bright orange on the sides while yearling males and females are more olive gray with a duller yellow. It was found that some yearling males were able to occupy the high quality mangrove habitat, but how and why could this be the case? Well, these birds were shown to have more black pigment and larger black patches in their feathers. In essence, they looked more like the adult birds. Were these birds simply quicker at maturing? It turns out, that during territorial disputes, redstarts will peck out the feathers of the sparring partner. In these young males, picking a fight led their feathers to be pulled out, and these feathers were replaced with more adult-like plumage. These birds were literally earning their stripes through territorial disputes!

This is all very interesting, and has immediate consequences for our understanding of these birds and their overwintering habits, but it gets even more interesting as we head back to breeding grounds in North America to see how overwintering condition affects breeding output.

American redstart, photo by Dan Pancamo Photography

First, the males in good condition from the mangroves are the first to leave the island. Females and yearling males leave later into April and May. Since the females have lower food resources over the course of the winter, they are in rather poor condition during migration, and many of the females in poorest condition see decreased success on breeding grounds. All of this increases the likelihood that females will die. The life cycle of the female helps us to understand the population dynamics in this species—the sex ratio in redstarts skews towards a higher ratio of males. Females might be more likely to die at any point during the life cycle, and the lower number of breeding females may limit the general population of redstarts.

Overall, the condition of the later-arriving male and female redstarts was poorer, and both sexes saw decreased reproductive success on breeding grounds. These studies were among the first to delineate carryover effects from non-breeding grounds, an important finding that  tropical wintering grounds—once thought of as a relaxing vacation for these birds—could limit populations and produce discernible patterns on breeding grounds. It's an amazing story, with one scientific study built upon another, to understand the ecology of this species.

Many questions remain to be answered. Might rising seas due to climate change reduce habitat on islands like Jamaica for redstarts and other neotropical migrants? Will a disruption of weather patterns cause more drought in the Caribbean and decrease populations of insects and thus populations of birds like redstarts? Furthermore, changing leaf out dates in North America have been proven to affect some species and their reproductive success. Might this be the case with the American redstart? Researchers think that the early arriving (healthy) males also find the best insect availability upon arrival. How might these changes in phenology bear out on breeding grounds? Clearly, the conservation and ecology of the American redstart is a complicated and ever-shifting matter. The next time you see a redstart frenetically jumping through an oak tree, you can speculate as to what habitat this redstart spent its winter, and subsequently the overall health of the bird. If it's a yearling male, you might even be able to tell how many fights he's been in.

Written by Drew Harry, Faville Grove Sanctuary land steward

For the Love of Birds

Our feathered friends have been greatly impacted by late winter and early spring storms.  Northern Wisconsin received frequent and heavy storms in April, while in southern Wisconsin we received two record breaking snow storms totaling 12 inches the third week of April. It was beautiful to see a snow covered landscape and we were rewarded with seeing tracks and body-slide marks from a pair of river otters at the sanctuary!

However, it is difficult to watch the birds trying to survive and it is important to help to the birds that we can. Some species that are impacted by the late storms cannot be helped, like the nesting sandhill cranes at Otsego Marsh and the Virginia rail that walked across our deck on April 17.

A sandhill crane remains on the nest through an April snowstorm. Photo by Richard Armstrong

Many other species of birds can be helped during storms and one way is to keep the bird feeders full with a variety of seeds. Our friend, John Kaiser, has been busy keeping feeders full outside of Hayward for a flock of 400 common redpolls. John really enjoys watching the birds, taking photos of them, and sharing photos and observations with friends.   

A redpoll oasis. Photo by John Kaiser

Another way to help birds out is to plant trees and shrubs that provide food and cover to help the birds during critical times. A perfect strategy is to have conifers adjacent to feeding stations. At the Kampen Road residence we expanded our spruce/white pine windbreak to help block the wind as well at provide cover for the birds.

This windbreak provides essential shelter for birds in winter storms. Photo by Mark Martin

In addition to the older conifers, we planted spruce, white cedar, red osier dogwood, American hazelnut along with crab apples and apple trees. An eagle scout’s project involved fencing the dogwoods to protect them from hungry rabbits and deer and the plantings are looking great after only a few years. We also prune the apple trees and leave the cuttings in a brush pile providing winter food and cover for the rabbits.

While not its favorite, a robin feeds off of crabapples after an April snowstorm. Photo by Mark Martin

Usually at this time of year, American robins are finding plenty of worms and getting ready for the nesting season. We often see our first broods of robins on Mother’s Day. This spring the robins are trying hard just to survive. We have seen them feeding on sumac, crab apples, and on the few remaining apples hanging on the trees. These shrubs and trees are not preferred food but will help them survive during these difficult times. Jacqueline Komada, summer intern, counted seven robins, a black-capped chickadee, a song sparrow, and a fox sparrow feeding  in our sumac patch on the hill above the pond.

Jacqueline Komada, Goose Pond intern this summer, is looking forward to planting trees and shrubs. Photo by Mark Martin

Jim Edlhuber, wildlife photographer from Waukesha County enjoys planting trees and shrubs for the birds as well at photographing them. Jim recently wrote “While birding Lake Park in Milwaukee one of the highlights was watching the northern flickers, yellow-shafted feeding on a couple of clumps of staghorn sumac. Three or four northern flickers hit these plants hard for seeds probably with anticipated snow coming and the ground having 4″-5″ of fresh snow down now. I have never seen northern flickers on sumac before. Many American robins and black-capped chickadees hit these plants hard too and while I was there, a pair of eastern bluebirds even checked out the seeds but did not stay.”  

A beautiful northern flicker helps itself to sumac. Photo by Jim Edlhuber

Jim also wrote “Getting people to plant things for birds? We can't do enough of that. We plant fruit bearing trees every year and a lot of them, just for the BIRDS!” This spring Jim is planting over 200 stems of 12 species ranging from dogwoods to swamp white oaks.

Crabapple trees are both useful and beautiful! Photo by Mark Martin

Crab apples are an excellent species to plant in your yard.  In addition to providing color in May the blossoms also provide nectar for bees.  There are many varieties of crab apples and we recommend planting varieties that “provide food for the birds” by holding their fruit over winter into spring. Three excellent books for selecting trees and shrubs to plant are:  

• Douglas Tallamy, Bringing Nature Home – How You Can Sustain Wildlife with Native Plants

• Steve Kress, The Audubon Society Guide to Attracting Birds

• Mariette Nowak, Birdscaping in the Midwest

We are fortunate to live in Columbia County where for many years the County has a tree and shrub program. This year they sold over 40,000 stems to land owners that are excited to help birds and other wildlife. If you would like to help us plant Washington hawthorns, red osier dogwoods, and white cedar, please contact us at goosep@madisonaudubon.org.

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

A Goose Pond Goodbye

Dear Audubon members and friends, I am sorry to announce that this is my last week at Madison Audubon Society. I have loved my time working for MAS, and it has been a privilege to be the land steward for Goose Pond Sanctuary. A privilege because the more I gave to the sanctuary, in sweat and time, the more I got back in experience, in beauty, in fulfillment.  I will always cherish the time I had here. For my last Friday Feathered Feature I wanted to share with you some of my favorite bird moments over the seasons at Goose Pond Sanctuary…

Maddie and her husband Aaron share in the thrill of meeting a snowy owl in January 2018.
Photo provided by Maddie Dumas

I love the birds of winter. The busyness at our feeders, the high-flying rough-legged hawks that silently cast shadows over the still, white landscape, and, if we’re lucky, the short-eared and snowy owls. I will never forget the night that Mark sent me and Caleb, a former intern, out to do one last owl scout at the end of a bitterly cold day in December. We drove around for the better part of an hour with no luck. Then, pausing up near the UW quarry, in one of those happy twists where the rock you thought you saw turns out to be an owl, Caleb spotted a short-eared owl hunkered down on a fencepost. A moment later we saw another short-ear glide silently over the same field.  This was enough to buoy us and as it was very nearly dark, we started to head back to the house. On our way we drove past the pond and the snags of cottonwoods that hug the east pond. It took us a moment to realize that we had driven right past a snowy owl sitting on the shorter snag. We carefully backed up and observed it for a moment before it flushed, and flew over the west pond to land on the ice, alarming the few brave Canada geese that remained this late in the season. In a matter of minutes a seemingly fruitless owl prowl had turned into a threefold sighting.

A turkey hen pauses to scope out her surroundings. Photo provided by Maddie Dumas

As spring arrives, the pond floods with waterfowl and the birds begin to brush up on their dancing in preparation for mating season. It’s always a joy to see the sandhill cranes hopping, bowing, and sweeping their huge graceful wings for their mates. Likewise, the drama of the northern harrier skydance is hard to beat. All this bravado leads to the happy observations of early summer. I can recall one morning when, all alone and heading up the trail in the Kubota, I saw a hen turkey up ahead on the trail. I stopped the vehicle and sat still to watch 10, 11, 12, 13 or more turkey chicks stumble across the trail, the last one dawdling well behind the others, until it looked up and, seeing itself alone, took off like a shot into the tall grasses. Another unforgettable family moment was when, working with the interns, we flushed a female harrier. Approaching the area where she flew, we were treated to the sight of her nest, complete with two feisty chicks who glared up at us with open bills before dashing off the nest and into the prairie at surprising speed. We took off with speed ourselves so as not to disturb them further.

The unmatched beauty of a Goose Pond summer. Photo provided by Maddie Dumas

In the heat of summer, the prairie wildflowers are the pleasantest way of marking the passing of the season. Unfortunately, the invasive weeds are just as regular a timepiece. Well past parsnip season and deep into the drudgery of sweet clover season, a late afternoon can drag on slower than your feet through the lush prairie as you fight your way out to an isolated clone.  It’s there, digging and pulling and sweating and hoping you’ve found the last of it (and you never have), that the sweet call of the Eastern meadowlark might make you pause. You will look around for the bird, and maybe spot it, or maybe not. But either way, that momentary lapse in your single-minded pursuit has caused you to observe the beauty around you. The call of the meadowlark reminds you why you’re there in the sweetest way possible.

A ringed-necked pheasant provides a spectacular view for the lucky beholder. Photo provided by Maddie Dumas

In fall the waterfowl return to the pond in full force. Every morning is a scavenger hunt, counting the birds on the pond, feeling that rush of adrenaline when you spot something new (a raft of redheads!), or in great quantities (100 snow geese!). Even better, long satisfying days collecting and sorting prairie seed blend into cool, dark nights where the last sounds you hear before falling asleep are the honking and splashing and whistling of the ducks, geese and swans. One fall night Aaron and I heard a great-horned owl hooting around dusk, a pack of coyotes yipping in the middle of the night, and a pheasant barking us awake in the morning; all this vying to be heard over the cacophony coming off the pond. Whoever said it was quiet living in the country?!

These experiences will forever mark a special time in my life. A time when my job meant spending the entire day outside in nature. When my work and home and passion all blended harmoniously into one. I will continue to work in the field of restoration ecology, but I don’t know when I’ll ever again be so immersed in it. May everyone be so fortunate as to have a job like this once in their lives. Thank you to everyone who gave me this opportunity, to those who livened my days by working with me, to those who educated me (whether they knew it or not), and to all who work to protect our wildlife and planet.

Written by Maddie Dumas, Goose Pond Sanctuary land steward (last day: March 21, 2018)

Red-shouldered Hawk

Photo by Arlene Koziol

The red-shouldered hawk occasionally winters in Wisconsin, and can be found throughout the state in mostly forested habitat, though most birds migrate south for the winter. At Everglades National Park earlier this month, I was able to see red-shouldered hawks in a different habitat than they use in Wisconsin, as these Florida birds soared in their characteristic Buteo style over the open sawgrass glades.

The diet of the red-shouldered hawk speaks to its adaptability. Currently, wintering Wisconsin birds will hunt small mammals, mourning doves, house sparrows, and starlings, in addition to carrion. Winter birds have also been noted at feeders. Habitat for overwintering birds changes a bit from breeding habitat, as the hawks will occupy more fragmented landscapes like woodland edges, parks, and even suburban or urban residential areas.

By mid-February, the hawks will start migrating north to establish territories. The habitat most associated with breeding red-shouldered hawks is mature lowland forest, though contiguous areas of upland forest, like the Kettle Moraine, will also provide breeding habitat. Most important to the hawks are water features, and ephemeral ponds of the Kettle Moraine provide good substitute for the typical riparian habitat.

Photo by USFWS Midwest

With the return to breeding grounds in mid-February, the hawks typically coincide with the emergence of chipmunks from hibernation. This marks an important food source for the birds year-round, but especially at this time of year.  It is thought that chipmunk population cycles might play a role in the breeding success of red-shouldered hawks.

Once the snow thaws, the adaptable diet of red-shouldered hawks really stands out. One study in Iowa found that during a dry year, 92% of prey items delivered to nests were small mammals. During a wet year, 85% of prey items were amphibians and arthropods. Nesting in these dynamic and productive lowland forests, red-shouldered hawks are able to maneuver between different prey items to suit their needs. They'll even supplement their diet with crayfish and fish. Consuming amphibians as an important part of their diet, these lowland forests and ephemeral forested ponds—noted for amphibian abundance—provide ample hunting opportunities for these birds.

Photo by Arlene Koziol

Red-shouldered hawks show a high site fidelity, and will oftentimes return to the same nest 3 to 4 years in a row. They typically form long-lasting pair bonds. Nests are typically built in massive trees, often red oaks in Wisconsin, built more than halfway up the tree and lined with conifer sprigs upon spring arrival. In areas like southern Wisconsin where evergreen leaves are hard to find, the resourceful hawk might decorate with birch bark or mosses or lichens.

Red-shouldered hawk and nest. Painting by Peggy Macnamara

Viewing the red-shouldered hawk's distribution in Wisconsin on eBird, one sees some major veins of observations: the Wolf River, Chippewa River, Wisconsin River, Mississippi River, and Kettle Moraine. These large river and forest systems have intact and contiguous floodplain forests to support these birds. Cutting of forests, even small-scale selective cutting, can have detrimental effects on red-shouldered hawk nesting habitat since red-tailed hawks and great horned owls will displace red-shouldered hawks as habitat becomes more fragmented.

Here at Faville Grove, the red-shouldered hawk habitat is rather lacking, as the open landscape and lack of contiguous forest cover discourages these birds from nesting. However, it wouldn't be out of the question to see a red-shouldered hawk here during the winter. Additionally, the opposite side of the Crawfish River historically supported rich deciduous forest, with the Crawfish serving as a firebreak between the prairie on the western side and forest on the east, and it's not hard to imagine the terrific habitat such a forest would have provided.

Written by Drew Harry, Faville Grove Sanctuary land steward