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Cofrin Center for Biodiversity

Point au Sable Bird Survey: October 26, 2011

Josh Martinez and I conducted point counts at several Point Sable sites this morning. The sky was overcast and the wind speed was around 10 mph. There were quite a few ducks visible from the end of the Point but none were close enough to identify. The most exciting bird of the day was a Horned Grebe (Podiceps auritus) on the bay just off the outlet of Wequiock Creek. We also saw 3 Hermit Thrushes (Catharus guttatus), a Bald Eagle (Haliaeetus leucocephalus) and several species of woodpecker including a very cooperative Downy Woodpecker (Picoides pubescens; see photo). Overall, it was a very quiet morning for birding.


Horned Grebe

Distant Horned Grebe on the bay of Green Bay, October 26, 2011


Downy Woodpecker

Male Downy Woodpecker, Point au Sable, October 26, 2011.


Wind Damage at Toft Point Natural Area

Winds of up to 69 mph swept through Door County on Thursday, September 29th causing extensive damage, especially on the west side of the county. Thousands were without power for two days and Highway 57 between Jacksonport and Baileys Harbor was closed through Saturday. All the state parks located in the county were closed for the weekend.

Toft Point natural area, managed by the Cofrin Center for Biodiversity, is located in Baileys Harbor, WI and was in the path of the windstorm. At least 24 downed or broken trees were counted by the Friends of Toft Point as they inspected the trails on Sunday.

Fallen tree at Toft Point

Toft Friend Charlotte Lukes sits on a fallen tree at Toft Point Natural Area. Photo by Roy Lukes.

Josh Martinez, land steward for the Cofrin Center for Biodiversity will be heading up with UW-Green Bay facilities staff to clear the road and trails at Toft Point on Friday, October 7th. We ask that people remain off the trails and road until after trees can be removed to avoid injury from leaning trees and branches.

Leaning trees

Trees leaning over the trail at Toft Point. Photo by Roy Lukes.

Web links and new design

We have consolidated our blogs to this single site.  You can get where you want by clicking on categories listed in the right hand panel. Please note that the links  inthe main menu only return you to our old website.  Ths will be changing as we load up our newly redesigned site in a few weeks.

Flycatchers Switch to Berrypicking in the Fall

The borders of the Lenfestey Family Courtyard are heavily planted with elderberries and each August and September as they ripen I have great views out my window of the birds that come to feast. There are always the usual bunch, the robins and their young that nested all summer in the Serviceberry, Cardinals of course, and the flocks of Cedar Waxwings that easily navigate the tangle of branches like bands of pirates finding the richest caches of fruit.

Eastern Kingbirds

Eastern Kingbirds foraging on elderberries. Shot through my office window. Note the textbook reflected by the flash.

But there are Eastern Kingbirds joining the party too. Kingbirds rarely visit the courtyard, preferring the open edges of the trail near the ponds where they gracefully dive and roll, capturing flying insects in their pincer-like beaks. It is strange to see them flapping through the dense foliage of the elderberries, where they tip themselves forward off the branches as they clumsily pluck berries one by one. And while they seem a bit unfamiliar with the technique they do manage to gorge themselves with fruit.  Fruit-eating also coincides with a remarkable tolerance in this notoriously aggressive species. Kingbirds will flock together during migration and in their South American wintering grounds.

Scientists have long recognized this feeding switch from insects to fruit in several species of primarily insectivorous birds shortly before and during migration.  It was originally thought that the birds switched to fruit as insect populations declined, but this does not seem to be the case. It was also hypothesized that fruit might provide more calories, but nutrition studies showed that while some species did gain weight on fruit others lost weight (Smith et al. 2007).  Other research has focused on the advantages of feeding on fruit.  Insects require a lot more energy to find and capture and are usually caught on the wing, exposing birds to migrating hawks. Berries offer an easily collected high density food source and the foliage offers cover from hawks and other predators.  Studies have also shown that birds do seek out berries that are highest in proteins and lipids (Parrish, 1996).

Just this year scientists have started to look at micronutrients including antioxidants in fruit. Migration is extremely stressful and scientists speculate that ingesting more antioxidants might improve these birds ability to survive during migration and in tropical wintering grounds where birds are packed closer together (McCue et al. 2010).

It has even been suggested by ornithologist Gene Morton (1971)  that the white tip on the Eastern Kingbird’s tail might analogous to the bright tail feathers of the waxwings. As they forage tail flicks signal food locations to others in the flock .

Regardless of the physiological reasons migratory birds are switching to fruit, the take-home message is strong.  Make sure that migrating birds have access to reliable sources of fruit in the fall. Both Parrish’s and McWilliams’ research suggests that native berries, are superior in nutrition to non-native species. We need to make sure that we preserve native habitats along migratory routes so that birds have reliable high quality food during stop-overs.

Parrish (1996) also argues for us to become better land stewards of our own yards. “Conserving native habitat in a backyard is simple and inexpensive,” he said.  “Many songbirds will even use small, yard-sized patches of these natural landscapes during migration, providing people with exciting opportunities for bird observation–and providing the birds with the critical fuel for a long journey south.”


McCue, M. D., O. Sivan, S.R. McWilliams, and B. Pinshow (2010) Tracking the oxidative kinetics of carbohydrates, amino acids, and fatty acids in the house sparrow using exhaled 13CO2. Journal of Experimental Biology, in press.

Parrish, Jeffrey D. (1997) Patterns of Frugivory and Energetic Condition in Nearctic Landbirds during Autumn Migration. The Condor Vol. 99, No. 3 (Aug., 1997), pp. 681-697

Morton, Eugene S. (1971) Food in migration habits of the Eastern Kingbird in Panama. The Auk: 88: 925-926.

Smith, Susan B., Kathleen H. Mcpherson, Jeffrey M. Backer, Barbara J. Pierce, David W. Podlesak, and Scott R. Mcwilliams (2007) Fruit Quality and Consumption by Songbirds During Autumn Migration . The Wilson Journal of Ornithology 119(3):419–428

Turner, Scott (1996) Study shows songbirds switch from bugs to berries to fuel fall migration. Brown University news Bureau.

Point au Sable Bird Survey: October 1, 2010 by Erin Gnass

In a short amount of time, undergraduate student, Aaron Groves, and I were able to trek over to Point au Sable and perform just one point count along the shoreline before the downpour of rain began! Upon arriving at the Point, we noticed that the landscape had changed drastically since we had last been there a few months ago. The shoreline was completely covered in the invasive Phragmites australis, making it nearly impossible to view the bay of Green Bay. Regardless, many of the small passerines did not seem to mind this invasive. We found numerous Black-capped Chickadees, Song Sparrows, and one Myrtle (Yellow-rumped) Warbler foraging within the Phragmites and using it for cover. We also observed the following species:  Great Egret, Great Blue Heron, Mallard Duck, Canada Geese, Ring-billed Gull, Red-winged Blackbird, Common Grackle, Ovenbird, Downy Woodpecker, Gray Catbird, White-breasted Nuthatch, American Crow, Blue Jay, and American Robin. Upon hearing the chatter of the Belted Kingfisher and the ever-present European Starling, the rain slowly started to pour, at which point Aaron and I left for the day. We observed a total of 19 species.

Brown, Kewaunee, Shawano, and Oconto Bird Surveys: May 26 to June 24, 2010 by Erin Gnass

As I mentioned in one recent blog posting entitled “May 26, 2010 by Erin Gnass,” I performed bird surveys for the greater part of the month of June for my thesis project—the index of ecological condition model, as applied to northern hardwood forests of Wisconsin. In order to most appropriately create this model, I surveyed additional hardwood forested sites considered to be of poorer forest condition so as to sample across a wide range of environmental condition. This enables the model to be more accurate and effective at calculating forest condition. Therefore, I went in search of hardwood forest sites on both public and private lands near and within heavily managed, fragmented, and human-disturbed or developed areas. Within Brown, Kewaunee, Shawano, and Oconto counties here in east-central Wisconsin, I found 27 sites that I surveyed, with the much-appreciated assistance of Joan Berkopec (the same wonderful volunteer who helped with the Wild Rivers Legacy Forest surveys and the Nicolet National Forest Bird Survey that I described in the two previous posts).

From May 26 until June 24, I observed 49 total species at these 27 additional sites, including the following species of interest:

Seven warblers:  Chestnut-sided, Common Yellowthroat, Mourning, Northern Waterthrush, Ovenbird (in moderate numbers), Pine, and Yellow Warblers

Seven woodpeckers:  Downy, Hairy, Northern Flicker, Pileated, Red-bellied, Red-headed, and Yellow-bellied Sapsucker Woodpeckers

Four flycatchers:  Eastern Phoebe, Eastern Wood-Pewee (in moderate numbers), Great Crested (in moderate numbers), and Least Flycatchers

Three thrushes:  American Robin (in moderate numbers), Veery, and Wood Thurshes

And one vireo:  Red-eyed Vireos (in large numbers)

Please feel free to look at the photographs that I took shown below:

Hardwood forest in Brown County

WI DNR sugar maple forest plot in Shawano County

While scouting out potential survey sites in Brown County, I heard then observed this spectacular Mourning Warbler pictured here

One of two Red-headed Woodpeckers that I found nesting along the pond at the Brown County Pet Exercise Park, which is full of sugar maple hardwoods

Red-headed Woodpecker

One of the two Red-headed Woodpeckers at their nesting cavity site

Thank you to professional photojournalist, Scott Giese, my boyfriend, for taking these additional photographs of me while I completed a bird survey in Brown County:

Me, Erin Gnass, obtaining a GPS coordinate at a bird survey site in Brown County

Me, Erin Gnass, recording data for a bird survey in Brown County

Me, Erin Gnass, trying to obtain a visual observation of a bird during a bird survey in Brown County

June 11-13, 2010: Nicolet National Forest Bird Survey by Erin Gnass

Every year since 1987, a large group of ornithologists have performed breeding bird surveys within the Nicolet National Forest (NNF; see the Nicolet National Forest Bird Survey: ( in northeastern Wisconsin, now contributing to well over 40,000 records of birds consisting of over 200 total bird species. Whether you are an ornithologist by profession, a volunteer, a student, a back-yard birder, the state’s best expert, or a complete novice who has never seen a Canada Goose in your life, absolutely anyone can come and assist in the survey! Luckily, I was able to be one of the group leaders and engage myself in the survey for the very first time. Having heard about how much fun and exciting it is to participate in such a wonderful annual event, I was not disappointed in the slightest!

On the first day of the survey, I led a small team birders consisting of a young couple and another woman to pine and hardwood forests and a few beautiful bogs. Although the sites were not as biodiversity rich as other sites within the Nicolet National Forest, we were able to observe many interesting but “usual suspect” birds, such as the Ovenbird, Red-eyed Vireo, Chipping Sparrow, Eastern Wood-Pewee, Rose-breasted Grosbeak, American Robin, Brown Creeper, Blue Jay, Black-capped Chickadee, Black-throated Green Warbler, Alder Flycatcher, Yellow-bellied Sapsucker, and many others. After this first morning of surveys, a large group of us, including (some of my favorite ecologist/biologist friends) UWGB undergraduate student, Aaron Groves, former UWGB Environmental Science & Policy graduate student, Kathryn Corio, Ron Eichhorn (who helped the Nature Conservancy and me with the WRLF project), and a few others went out to a bog near the NNF to look for interesting plants and birds. A few of us chased down a Palm Warbler while others observed uncommon plant species. Please see the photographs that I took down at the bottom of this posting. Thank you to all of the botanists in this group who showed me these beautiful plants.

On the second day, graduate student, Nick Walton, joined our group and helped to lead the surveys.  Near the end of one of the last surveys of the day, we heard a nearby soft chickadee-call where we discovered two Boreal Chickadees—the highlight of my entire summer. Not only did these individuals continue singing throughout the remainder survey, they flew low in the trees only ten meters away from us for quite a few minutes. Not many people have the opportunity to view this species in particular because they are considered an uncommon, northern U.S./Canada dwelling species. Thus, when we shared the news with other birders upon returning to the field houses, everyone expressed their surprise and excitement to us. What a thrilling day it was.

I look forward to next summer’s bird surveys at the Nicolet National Forest.

My photographs:

Me, Erin Gnass, leading one of a few bird surveys in a bog within the Nicolet National Forest

One of a few beautiful bogs that we surveyed.

After the first day of surveys, a small group and I went in search of plants and birds around the bog pictured here.

UWGB undergraduate, Aaron Groves, bird watching at the bog.

Ron Eichhorn and Aaron Groves trying to identify a plant.

Aaron Groves, and his mother, former UWGB Environmental Science & Policy graduate student, Kathryn Corio

A stunningly gorgeous carnivorous pitcher plant (Sarracenia purpurea)

Another carnivorous plant, the sundew (Drosera rotundifolia)

Aaron Groves and I found a previously made teepee-like structure on a hill leading down to the bog.

Puddles of Sulfurs


puddling sulfurs

Sulfur butterflies puddling in a drainage ditch.

On a weekend in early August on a country road in Door Co., Wisconsin Mike Draney and I were surprised to find ourselves in a cloud of butterflies. Driving along County Road EE in Door County we were scaring up clouds of Clouded Sulfur butterflies (Colias philodice). We stopped and found that they were gathering by the hundreds in the wet mud of the stormwater ditches. We collected several dead butterflies, likely the victims of car traffic, and found that every individual we collected was a male.

Congregations of butterflies at mud puddles, animal dung, or carrion were first recognized in the early 1900s, but surprisingly, scientists still don’t know a lot about why they do it. It was long suspected the behavior was related to nutrients and salts. Flower nectar, while high in carbohydrates, is extremely low in nutrients like salts and amino acids.  Experiments by chemical ecologists S. Smedley and T. Eisner conducted in 1995 confirmed that butterflies do prefer saltier puddles. And since them numerous studies have confirmed that butterflies are seeking sodium or proteins and sometimes other nutrients in the puddles that are scarce in nectar.

Females are not usually seen at puddles, even though it makes sense that they would also be in need these scarce nutrients to produce healthy eggs. In fact it has been demonstrated that males transfer some of the nutrients they collect at puddles to females as “nuptial gifts” during mating that she will then use to provision her eggs. In some cases may give away almost half of their total reserves.  The gift is important because larvae that are born with higher amounts of nutrients probably have an advantage in surviving especially in low sodium environments. (See Molleman et al. 2005 for more information)

But why so many of this species?   Clouded Sulphur caterpillars feed on legumes like alfalfa and clover, and there can be as many as 3 generations in favorable years, so it isn’t surprising to expect to see large numbers of them in agricultural areas in mid to late summer.

But Sulphurs aren’t the only butterflies you might see visiting puddles, many other species of   terrestrial arthropods that have low salt diets including Blattodea, Diptera, Diplopoda, Hemiptera, Hymenoptera and Orthoptera have also been observed to puddle.


Molleman F, Grunsven RHA, Liefting M, Zwaan BJ, and Brakefield PM, 2005. Is male puddling behaviour of tropical butterflies targeted at sodium for nuptial gifts or activity? Biological journal of the linnean society. 86: 345-361   

Smedley and Eisner, 1995. Sodium Uptake by Puddling in a Moth. Science. 270: 1816-1818

May 30 to June 5, 2010: Wild Rivers Legacy Forest by Erin Gnass

One of the many exciting bird research projects that I helped to investigate this summer was with the Nature Conservancy (TNC) in the Wild Rivers Legacy Forest (WRLF) north of Armstrong Creek in northern Wisconsin. With a field crew of eight people, many of us living in one field house, we not only gathered very useful bird survey data for TNC and my graduate thesis project, but we were also fortunate enough to listen to and observe many unique and beautiful bird species. Every afternoon or evening, we met as a group to decide how to break apart all of the required bird survey sites within the forest. Some of us went out in pairs while others surveyed independently to perform as many bird point counts as possible between the half hour prior to dawn until 9:30 AM (the short window of time that breeding birds are allowed to be surveyed). Depending on the terrain, distance between points (via car or on foot), and weather, many pairs or individuals performed as few as 5-6 surveys to as many as 12 in a morning! Therefore, we finished all 200 bird survey sites in the WRLF and the 23 additional sites of poor ecological forest condition in one week’s time!

For some of the bird sighting highlights of this week during the first week of June, we viewed 73 total species within the WRLF including:

16 warblers:  American Redstart, Black-and-white, Blackburnian (in large numbers), Black-throated Blue, Black-throated Green (in large numbers), Canada, Common Yellowthroat, Chestnut-sided, Magnolia, Mourning (in large numbers), Myrtle (the official name of the eastern population of the Yellow-rumped Warbler), Nashville, Northern Parula, Northern Waterthrush, Ovenbird (in large numbers), and Tennessee Warblers

Six flycatchers:  Eastern Kingbird, Eastern Phoebe, Eastern Wood-Pewee (in large numbers), Great Crested, Least (in large numbers), and Yellow-bellied Flycatchers

Six woodpeckers:  in comparison to last year’s data, we observed many more woodpecker individuals:  Downy, Hairy, Northern Flicker, Pileated, Red-bellied, and Yellow-bellied Sapsucker (in large numbers) Woodpeckers

Five thrushes:  American Robin (in large numbers), Hermit Thrush (in large numbers), Swainson’s, Veery, and Wood Thrushes

Four birds of prey:  Broad-winged Hawk, American Kestrel, Barred Owl, and Red-shouldered Hawk

Two vireos:  Red-eyed (in large numbers) and Blue-headed Vireos

And several other birds of interest included:  Black-billed Cuckoo, Black-capped Chickadee (in large numbers), Blue Jay (in large numbers), Brown Creeper, Common Raven, Chimney Swift, Evening Grosbeak, Indigo Bunting, Purple Finch, Rose-breasted Grosbeak (in large numbers), Red-breasted Nuthatch, Scarlet Tanager (in large numbers), White-breasted Nuthatch, White-throated Sparrow (in large numbers), Winter Wren, and Yellow-billed Cuckoo.

In comparison to the 200 sites of the WRLF, we only observed 47 total species within the sites of poor ecological forest condition, including many of those observed within the WRLF. In these additional sites, however, we also observed the Eastern Bluebird, Eastern Meadowlark, Golden-winged Warbler, Ring-necked Pheasant, and Yellow-throated Vireo, which were not observed during point counts in the WRLF.

For fun in the afternoons, we would gather for lunch at a nearby lake, such as Savage Lake, and enjoy the Black Terns, Sandhill Cranes, and Common Loons, which foraged within a few hundred meters of us. Other days we searched for different bird species (e.g. Bobolink) and other walks of life, such as dozens of dragonfly species, as expertly identified by Ron and Joan. We ran into several deer and quite a few black bears, including one close call during a survey that I was conducting by myself. Around minute three of one ten-minute bird point count survey that I was doing, a large black bear peered through thick brush about 25 meters away from me. After shooing it away from me, it still remained close, only about 200 meters away. Upon completing the bird survey and heading back to my car, it stood on its back legs and kept a close watch over me! Thankfully, it continued to forage and stay clear of me.

In one short week’s time, our dedicated and tireless field crew performed many surveys, which provided this study with incredibly useful data that will contribute towards a vastly important conservation project for the future. Luckily, I had some of the most fun that I have ever had working on a bird field crew and am grateful to be a part of this project. Thank you to all of those expert birders on this crew who helped me to become a better birder!

Please take a look at some of the photographs that I took during this week.

TNC's Nick Miller and John Wagner

Lunch break

Dragonfly emerging

TNC John Wagner and volunteer Joan Berkopec with the field crew dog, Pogo

Sandhill Crane foraging along the muddy edge of a lake

Forest road leading to a few of the last bird surveys that I performed just north of Goodman, WI

How NOT to Control Gypsy Moths

Burlap tree wrap.

Burlap "skirt" tied around young oak.

One of the most common ways to try to control gypsy moth (Lymantria dispar) populations is to wrap tree trunks with control bands. These are simply burlap skirts that are wrapped around the tree. Gypsy moths feed on the leaves of the trees at night and then climb back down the tree trunk and hide under the bark or leaves during the day to avoid predators. The burlap skirts provide an ideal hiding spot for the caterpillars and they will congregate there in large numbers. This makes it easy to capture and kill them during the day. The burlap itself does not act as a trap, and actually increases the moth’s chance of surviving to adulthood, because it prevents predators like Blue Jays from seeing them. Burlap only works if the caterpillars are removed every few days. So if you are going to put up the burlap skirts, you must be committed to checking them every few days and killing the caterpillars by squishing them or by scraping them into a jar of soapy water so they drown.

We saw thousands of male gypsy moth flying around burlap skirted oak trees in one of the parks in Green Bay, Wisconsin in July of 2010. There were many females actually laying their eggs underneath the burlap.  This is unfortunate because now there will be more work to remove egg masses this winter and spring.

Burlap lifted revealing gypsy moth pupae.

Burlap lifted revealing gypsy moth pupae.

Some Links on How to properly use burlap tree skirts:

Male (dark) and female (light) gypsy moths with egg masses.

Male (dark) and female (light) gypsy moths with egg masses.