Double-crested Cormorant

In the first Breeding Bird Atlas of Wisconsin, Sumner Matteson wrote that ornithologist J. Ludwig stated that double-crested cormorants are one of our most elegant and misunderstood colonial waterbirds.  Cormorant numbers have changed greatly over the past 100 years.

Sam Robbins in 1991 Wisconsin Birdlife referenced an article in the LaCrosse Tribune that reported on a flight of cormorants on April 24, 1926, “It continued for two and one-half hours, more or less intermittently, ...The flight was so large that at times it was impossible to see the sunset sky through the mass...The numbers of birds is variously estimated at from 100,000 to 1,000,000.”

Sumner also wrote that “The first documented breeding occurred in 1919 and 1921 (13 nests) in dead trees on the Okee Flowage (Wisconsin River) in southwestern Columbia County.  Victor Martin, Mark’s father, told the story of his brother that shot a cormorant while duck hunting on the Marshall millpond in Dane County around 1925.

Robbins wrote that “By 1960 only three to five birds were observed per season outside of the few remaining breeding colonies.”  A variety of factors contributed to their great decline including commercial fishermen that killed birds at the rookeries, large areas of dead trees in flowages that provided nesting sites eventually fell down and DDT impacted their reproduction.    Robbins wrote “the cormorant became a prime candidate for the endangered species list established in 1973.”

Photo by Richard Armstrong

Mark met Tom Meier, another wildlife major at UW-Stevens Point that did his master thesis on erection of artificial platforms at the Mead Wildlife Area in Marathon County.  Tom found that the platforms benefitted cormorants as well as great blue herons.    

With the erection of nesting platforms, a reduction in the impact of DDT and protection by being listed as endangered, their numbers recovered and they were removed from the endangered species list in 1985.  Their numbers continued to increase.  Mark and Sue remember in the mid 1990s having a picnic with Mark’s parents in May at a public boat launch on Moonlight Bay near Baileys Harbor in Door County and seeing a flock of comormants that were flying just over the water, one following another, that passed uninterrupted for 20 minutes! 

The first breeding bird atlas (1995-2000) reported that cormorants were confirmed in 24 atlas blocks and the recently completed Atlas II had confirmed nesting from 44 atlas blocks.  Sumner estimated from his 1997 surveys that there were 10,546 pairs nesting in Wisconsin.  At the beginning of this century, the U.S. Fish and Wildlife Service began controlling their numbers by oiling eggs in the Door County Area to improve fish numbers for commercial and sport fishermen.  However, breeding bird atlas reported in the past five years documented over 13,000 birds nesting on Door County islands.  

We will long remember an atlas trip with Pat Clark, MA board member and Dory Owen and her husband Phillip to Babe’s Island in Beaver Dam Lake last July.  We counted 450 cormorants, including at least 25 young.  Their nesting trees were dead or dying due to the buildup of guano.   The only atlas report of breeding cormorants in Columbia County was reported in 2018 by Laura Wentz who found four adults and 10 young at the Baraboo River Waterfowl Production Area southwest of Portage.

Photo of cormorants and pelicans by Dory Owen

We have seen a few cormorants at Goose Pond in the past. This year they have been around for the past few weeks and Erica Heinig entered 60 on eBird on April 25th and this is the record high count for Goose Pond.  Mark and Graham also counted 60 individuals on May 5th.

Cormorants can be seen sitting and drying off on rocks on the east side of the east pond, flying around or fishing.  They are interesting birds to watch.  You might first see 10 birds fishing together and 20 seconds later another 7 appear.   Cornell Lab of Ornithology reports “They eat a wide variety of fish (more than 250 species have been reported), and they have impressive fishing technique: diving and chasing fish underwater with powerful propulsion from webbed feet. The tip of a cormorant’s upper bill is shaped like a hook, which is helpful for catching prey.”

The hook on this cormorant’s bill is quite noticeable! Photo by Richard Armstrong, taken at Goose Pond

At Goose Pond they are feasting on fathead minnows.  The pond was bone dry in 2012 and when the water returned in 2013 it was only a month or two and before we noticed fathead minnows that might have arrived as eggs in the feathers of waterfowl.

Fathead minnows are about four inches in size and can greatly multiply.  Females can lay 100 to 200 eggs per spawn and can spawn every four to five days.  The eggs hatch in four to eight days and the young can breed and lay eggs later in summer.  There must be thousands and thousands of fatheads minnows available for these “elegant” birds with snake-like heads.

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

Header photo by Richard Armstrong

Range map provided by AllAboutBirds.org

Cool Facts from the Cornell lab

• From a distance, Double-crested Cormorants are dark birds with snaky necks, but up-close they’re quite colorful—with orange-yellow skin on their face and throat, striking aquamarine eyes that sparkle like jewels, and a mouth that is bright blue on the inside.

• The double crest of the Double-crested Cormorant is only visible on adults during breeding season. The crests are white in cormorants from Alaska and black in other regions.

• Cormorants often stand in the sun with their wings spread out to dry. They have less preen oil than other birds, so their feathers can get soaked rather than shedding water like a duck’s. Though this seems like a problem for a bird that spends its life in water, wet feathers probably make it easier for cormorants to hunt underwater with agility and speed.

• In breeding colonies where the nests are placed on the ground, young cormorants leave their nests and congregate into groups with other youngsters (creches). They return to their own nests to be fed.

• Accumulated fecal matter below nests can kill the nest trees. When this happens, the cormorants may move to a new area or they may simply shift to nesting on the ground.

• The Double-crested Cormorant makes a bulky nest of sticks and other materials. It frequently picks up junk, such as rope, deflated balloons, fishnet, and plastic debris to incorporate into the nest. Parts of dead birds are commonly used too.

• Large pebbles are occasionally found in cormorant nests, and the cormorants treat them as eggs.

• The oldest known Double-crested Cormorant was at least 22 years, 6 months old; it was banded in Ontario in 1984 and found in Louisiana in 2006.

Virginia Rail

Virginia rails seem to walk on water. Photo by Arlene Koziol

“Secretive marsh birds” sounds like a church festival band or a clandestine middle school group. However, in nature, secretive marsh birds include rails and bitterns, where they dwell in wetland realms rarely breached by humans. Though the birds are not objectively secretive, they are indeed hard to spot from where humans stand.

Virginia rails provide a terrific look into the adaptations of marsh birds; the vocalizations alone seem like they could come from any number of species.  Its “k-k-k-kerrrrrr” trill sounds like the note of a spring peeper. Its “kiddick” call sounds like a malfunctioning dial-up internet connection. Its grunts are low, fuzzy, and accentuated by squeaks. 

This rail builds up to 30 dummy nests in a year, resembling the crazed paranoia of another marshland counterpart, the marsh wren.

If you have walked in a marsh where a Virginia rail has walked, you might be aware how maladapted humans are to these environments and you might gain respect for the Virginia rail. On floating mats at the edge of open water, we punch through; whereas Virginia rails stay upright with their light bodies and wide feet, probing on mudflats and floating mats of marsh. Where species like rice cutgrass, sedges, leatherleaf, stunted shrubs, and poison sumac might cause unholy irritation in humans, the Virginia rail’s laterally compressed body and tough forehead feathers allow it to scurry through wetland vegetation with ease. Anyone who has walked through a southern Wisconsin marsh has come to realize that rubber boots quickly become overtopped and the pure muscle and flexibility needed to high-step through a marsh builds up plenty of lactic acid. Here too, rails outclass us, with the highest ratio of leg muscles to flight muscles in birds, explaining their tenacity in marshes and their reluctant and haphazard flight.

Check out the giant feet on this Virginia rail chick! Photo by Mick Thompson

Research has shown that Virginia rails can be quite discerning in terms of their habitat preferences. On average, wetlands dominated by the invasive reed canary grass make poor habitat for rails. With predators of their eggs like mink, otter, great horned owls, northern harriers, and even cranes and egrets, rails need a complex structural attributes in order to thrive. A monotype of reed canary grass, might be difficult to navigate even for a hardy Virginia rail, and this monotype lacks the diverse structure that allows for great feeding opportunities.

For instance, at the Laas Tamarack—where rails have been discovered breeding—a view from above shows the complex habitat that rails enjoy.

The Laas Tamarack is one of Faville Grove’s delightfully diverse habitats. Map created by Drew Harry

I’ve been through this area on foot, and it contains open water, floating mud flats, floating areas with dense cattails, elevated mounds of tussock sedges, elevated mounds from muskrat lodges, wet pockets of sedges and blue flag iris, hummocky areas of sphagnum moss, and willows, bog birch, and red osier dogwood.  This diversity of habitat provides good cover and foraging and nesting spots for a rail.

Blue flag iris, within the wetland complex at the Laas Tamarack. Photo by Drew Harry

In addition, where the mean C-value is higher (which corresponds to high-quality vegetation), there tend to be more Virginia rails.

At Faville Grove, we strive to reduce the reed canary grass as much as possible, and our restoration plantings focus on biodiversity and often result in high mean C values. All of this makes good habitat for rails, and last year a Breeding Bird Atlas volunteer found an adult Virginia rail with its young in the sanctuary.

You might hear Virginia rails around dawn or dusk in any of the marshy spots around the sanctuary, but with high water levels, it’s even more difficult than usual to navigate these spots. Living up to its reputation as a secretive marsh bird, a Virginia rail sighting may remain elusive this year.

Earth Day Bird Count

Calla is checking out the sights, photo by Graham Steinhauer

We decided to hold an “Earth Day” Goose Pond Sanctuary Bird Count to reflect on changes to the sanctuary over the past 50 years. On April 23, 2020, Graham Steinhauer and Calla Norris counted in one team while Mark counted by himself in order to maintain social distancing.

On a gray day like April 23, it’s difficult to guess what birds you will find. You see a few drab shapes (save for the striking black and white contrast of diving ducks) swimming in the shallows or flitting about in the bushes. It takes a decent pair of binoculars, patience, and some help from a field guide to figure out what is actually going on.

We were very pleased to find 53 bird species and 2,668 individuals. The water levels have remained high since March of 2019, and helped contribute to the high number of water birds. The three and one half hour count was conducted with clouds, 10 mile per hour winds and a high of 52 degrees. The 2020 spring migration for some species is late. Usually all geese have headed north except for one or two nesting pairs, and we were surprised to find 529 Canada geese, 70 cackling geese, 4 snow geese and 2 greater white-fronted geese. The main reason we conducted the count was to document early nesting species including Canada geese and ducks.  

The highlight of the day regards wood ducks. There are two duck boxes at Goose Pond, and one of them has been inhabited by hooded mergansers for the last six years. Where are the wood ducks? We probably have low densities of wood ducks because there isn’t a lot of woody cover. This year Graham erected a third duck box two weeks ago. He checked it yesterday (April 23) and voilà! A hen wood duck popped out of the box, and she was sitting on a clutch of eggs. This is the first record of wood ducks nesting at Goose Pond. 

Wood duck couple, photo by Monica Hall

Other observations of note include finding three goose nests in the Manthe wetlands on muskrat houses, 14 species of ducks including a pair of pintails and a lone male, a record of 175 mallards (129 pairs - 46 pairs seen and 83 lone drakes where the females are nesting),  43 double-crested cormorants, an estimated 464 tree swallows that were mostly hunting over the water due to cool weather and a record number of 53 yellow-rumped warblers that were also busy catching insects. Mark will long remember watching duck butts on the Manthe wetlands from Kampen Road.  There were blue-winged teal, northern shovelers, gadwalls, mallards, and northern pintails feasting in the shallow water.  

At feeders during this time of year we trade juncos for goldfinches, chickadees for white-crowned sparrows, and tree sparrows for blackbirds… red-winged and yellow-headed, as it turns out! For a period of five days, three yellow-headed blackbird males frequented bird feeders at the Prairie Lane Residence. We didn’t see any yellow-headed blackbirds during our count, but we’re delighted to have seen them within the last week.

Yellow-headed blackbirds looking at Graham, looking at them. Photo by Graham Steinhauer

Beyond the checklist itself, surveying all of the water and some of the uplands on Goose Pond’s 660 acres, gives you insight on the importance of each habitat or even microhabitat. We try to provide as many quality pieces of habitat for grassland, savanna, and wetland birds as we can. Here are a few examples of the specificities required by bird species. 

A beautiful yellow-rumped warbler, by Richard Armstrong

1. Green-winged teal were found almost exclusively in the wetland scrapes south of the Kampen Road Residence. 

2. Almost all of the yellow-rumped warblers were seen flying back and forth from a patch of sumac to large oak trees.  

3. 85% of ring-neck ducks were found in a thin isthmus of vegetation and flooded cottonwood stumps. We cut those cottonwoods in the winter of 2018.

4. 464 tree swallows were seen during this count, and they were either on their nest box, in the air, or on one particular small dead tree. There was seemingly nothing special about this tree besides that it was near the water where they were feeding. At least 120 tree swallows were seen occupying its few thin branches at a time.

5. One downy woodpecker was observed, and it was on the best (ask a downy what that means) of three snags at Goose Pond. 

Fifty years ago Madison Audubon had just acquired 60 acres along Prairie Lane, and restoration efforts did not begin until 1976 with the planting of the Bicentennial Prairie.  In 1970 there was very little nesting cover in the local area and no restored wetlands.

Today, Madison Audubon owns 660 acres that includes over 400 acres of restored prairie.  With the high water and our 20 acre acres of restored wetlands there are 180 acres covered by water in the local area.  Our neighbors Rollie and Lynn Manthe have their land in wetland and restored prairie habitat.  Judi Benade, a neighbor to the west, has another 75 acres of wildlife habitat.  The upland nesting ducks and grassland bird numbers have greatly responded to the increase in grassland cover.  

Fifty years ago, there were no Canada geese, wood ducks, hooded mergansers, sandhill cranes, northern harriers, or clay-colored sparrows nesting in the area. 

Sandhill cranes happily nest at Goose Pond Sanctuary in 2020. Photo by Arlene Koziol

In 1985 Mark and Sue began erecting kestrel nesting boxes and have greatly expanded the kestrel nest box project thanks to coordination by Brand Smith. On this day, we ran into Bob Bennicoff, a volunteer who was monitoring kestrel boxes. Bob had a smile on his face when he told us about the five pairs of kestrels nesting within a half mile of Goose Pond.

We also observed a number of bird watchers and one hiker on our trail system that enjoyed getting as close to nature as possible while maintaining a reasonable distance from other humans.  This has been an excellent spring migration and many people have visited to view the sanctuary and take a break from staying at home.

Looking back we are thankful to the many members, partners, and neighbors that have helped Goose Pond grow to benefit the prairie, wetlands,  flora and fauna, and our visitors.  The future looks bright for increasing the size and quality of Goose Pond Sanctuary as we move ahead to the 100th celebration of Earth Day! 

Written By Mark and Sue Foote-Martin, Goose Pond Sanctuary resident managers, and Graham Steinhauer, land steward

Brown-headed Cowbird

I came across this post from the Voyageurs Wolf Project on Facebook two weeks ago. The page is informative and worth a follow, and this post reveals a fascinating development in the ecology and behavior of wolves!

Of course, this is an April Fool’s joke. At first, I thought wolves were raising a bear, but it turns out these fictitious wolves were raising a sasquatch. It is all very ridiculous.

Enter the brown-headed cowbird, which actually — and successfully — pulls off this very ridiculous stunt on birds across North America, tricking another species into raising its young. While wolves raising bears and sasquatches is absurd; it is also very cute. Cowbirds, on the other hand, do not receive the benefit of the doubt regarding their cuteness when a poor yellow warbler is tasked with rearing a cowbird chick—a yellow warbler which might end up being 1/5th the size of the fully grown cowbird.

A yellow warbler foster mom with her giant brown-headed cowbird chick. Photo by Emilie Chen FCC

If we think of the yellow warbler as a full-sized wolf of 70 pounds, the black bear (brown-headed cowbird) it raises will be about 318 pounds, which is well above a healthy black bear male’s average weight of about 275 pounds.

The key difference: a yellow warbler raises that cowbird chick in the span of weeks, whereas the black bear takes at least a decade to become that size.

Sidenote: you can learn even more about cowbirds from Matt Reetz’s fantastic Evenings with Audubon presentation here, or in Carolyn Byer’s awesome Into the Nest feature called Cowbirds, everybody’s favorite villain.

Birds might be crudely classified as “things with feathers,” but that way of thinking obscures the incredible variations and adaptations of species, and the brown-headed cowbird probably gets overlooked despite its fascinating life history. E.O Wilson, in his book The Diversity of Life, states that the test of a complete adaptive radiation is “the existence of a species specialized to feed on other members of its own group.” The cowbird brings a twist to this parasitism; it tricks the host bird into feeding its young.

A wood thrush with its own and a brown-headed cowbird nestling. Photo by Kelly Colgan Azar

There are many admirable traits in cowbirds. The females are absolutely prolific at finding nests. Wisconsin just completed its second Breeding Bird Atlas. I participated in the search to find evidence of bird breeding activity—a fun but challenging enterprise. Looking for courtship or copulation, nests with eggs, birds carrying nesting material or food, or recently fledged young, among other things, is tasking. But cowbirds, laying up to 40 eggs in a season, manage to locate and lay eggs in dozens of nests. Upon reflection, I think I should have trained a cowbird female, like a falconer, to accompany my nest-finding expeditions.

Perhaps most impressive, the females then relocate each nest after they lay their eggs. With an enlarged hippocampus compared to males, these female cowbirds have the genius and persistence to bring their eggs into the world.

Mike Ehrmantraut, the famous character from Breaking Bad and Better Call Saul, said “there are two kinds of heists: those where the guys get away with it, and those that leave witnesses.”

The brown-headed cowbird female makes sure she leaves no witnesses. She is Ehrmantraut-esque in her ability to find and stake out the nest. Many scenes in Breaking Bad depict Mike staked out in his car for hours on end, where he eventually notes an interesting habit or behavior of the person he’s watching. Likewise, the female brown-headed cowbird swaps Mike’s 1988 Chrysler Fifth Avenue for brushy fencerows, field edges, and forest clearings—often a result of human disturbance. Here she watches her prospective host, and once a routine is discerned and the host leaves the nest to feed, our female cowbird races to the nest and quickly lays her egg. The deed is done.

Mike Ehrmantraut, observing from his car

Female BHCO, observing from her branch. Photo by Kelly Colgan Azar

But the work for the female is not done. While some opine cowbirds as deadbeats and lazy, the female stays vigilant, watching “her” nests. The cowbird will sometimes appear at a visible spot near the hosts and ensure that the eggs are being cared for. It’s as if the host parents are a witness about to give testimony to bring down a criminal enterprise, but the cowbird appears like a mafioso in the courtroom, and the testimony changes. Again, the behavior might be unsavory, but it is undoubtedly savvy.

What happens if these host birds testify? Many do, and American robins and brown thrashers can successfully eject cowbird eggs and fend off the cowbirds. Other birds will abandon the nest or build a nest on top of the previous one. Yet many birds are maladapted to cowbird parasitism. Researchers have found that when cowbird eggs are removed, the cowbirds will often return to the nest and teach a grisly lesson, destroying the remaining brood. The cowbird philosophy seems again pulled straight from the mouth of Mike Ehrmantrout, who said “The moral of the story is: I chose a half measure, when I should have gone all the way. I’ll never make that mistake again.” There is no half-measure with brown-headed cowbirds; if its egg is ejected, a tit for tat pattern will ensue.

There’s a fascinating Radiolab episode called “Tit for Tat” which explains the prisoner’s dilemma apparent during the Cuban Missile Crisis. One researcher ran a computer tournament where programmers tried to solve the prisoner’s dilemma and faced off against each other. Stacks of code were written, but the winning result was simple. Its first line was “be nice.” The second was “copy the other player’s move.” The program was called “tit for tat.” We see that this is an enthralling solution under this competitive environment. The episode goes on to describe how British and German soldiers, in the trenches during World War I, ended up engaging in a similar sort of scenario. At the lunch hour, both sides learned to cease fire. During Christmas of 1914, British soldiers crawled out of their dark trenches, drawn by the Germans candlelit trees and singing of “Silent Night”. Instead of shooting the exposed British soldiers, both sides decided to have a truce, and they mingled, traded, and drank—and the whole truce lasted a week in some instances. It’s as if, in the darkness of the front lines in December of 1914 the soldiers came together and found their shared humanity.

Back to our cowbirds, at about 20-25 days the juvenile in the host nest will become restless, and like those soldiers during World War 1, the bird sneaks off into the night. These young cowbirds do not find a Christmas truce, but they do find, apparently, their “cowbird-ness.” A clandestine meeting occurs, where the juveniles fly to cowbird roost sites around fields and spend the evening with other cowbirds. Experimental juveniles raised only by their host will end up learning the songs and calls of the host species.

Brown-headed cowbird club, photo by Patricia Pierce FCC

So, in a secret meeting in the middle of the night, the cowbird learns that like the popular mafia front of “waste management” the cowbird family business is “nest management,” and the juvenile returns to the host’s nest by morning, its identity known but its disguise burgeoning—the strong, silent type.

Written by Drew Harry, Faville Grove Sanctuary land steward

Hooded Merganser

Hooded merganser, photo by Mick Thompson

We always enjoy seeing hooded mergansers, especially when the males have their crests — also known as their “hoods” — raised and are in courtship display. The scientific name for hooded mergansers is Lopodytes cucullatus that means “hooded diver.” The crests can be raised and lowered in both sexes, and are a helpful identification guide for these small fish ducks, who with their narrow serrated bills, catch fish.  

Early naturalists in the 19th century listed hooded mergansers as “abundant” in Wisconsin and were found especially in forested areas near water. But Sam Robbins wrote in Wisconsin Birdlife in 1991 that hooded mergansers are uncommon summer residents in southeast Wisconsin. Columbia and adjacent counties were not not included in his breeding map for the species. Their numbers greatly declined due to loss of forested habitat that provided nest cavities and over harvesting by hunters. Sam wrote that “Theoretically, the bird’s summer range should blanket the state.”

According to the Cornell Lab of Ornithology “Hooded Mergansers are fairly common and their populations are stable and possibly increased between 1966 and 2015, according to the North American Breeding Bird Survey.”

Hooded merganser range map, provided by The Cornell Lab of Ornithology

We observed their numbers increase in Columbia County in the past four decades. In the 1980’s, we would see a few birds usually in spring migration. In the 1990’s, we began seeing a few nesting pairs. In the first Breeding Bird Atlas (1995-2000), hoodies were confirmed nesting in 12% of the statewide priority and 17% of the priority blocks in Columbia County. In the second Breeding Bird Atlas II (2015-2019), they were confirmed in 26% of the statewide priority blocks and 33% of the Columbia County priority blocks.

A freon nesting tube that was donated to us by the LaCrosse County Conservation Alliance. We replaced the freon tube with a cedar box. Photo by Richard Armstrong

Hooded Mergansers at Our Cabin Near Rio

We had two surprises on March 25th when we began our final check of our duck nest boxes at our cabin near Rio to make sure they were ready to go. The first surprise was finding two boxes that contained screech owl pellets. One of the boxes also contained a small uneaten bullhead. Usually one does not think of owls that go fishing.  

The second surprise was finding two nest boxes with hooded merganser eggs. One box had four eggs and the other had two eggs. So far at the cabin we have three merganser nests with the first eggs laid on March 21, 23 and April 1st. An early ice out and above normal temperatures probably contributed to the early egg laying.

Lovely merganser eggs. Photo by Mark Martin

Our plan at the cabin is to check 20 accessible nest boxes weekly and stop checking individual boxes after finding woodie or hoodie eggs. We also have three nest boxes with wood duck eggs that were first laid on April 3, 4, and 5.  

Nesting Hooded Mergansers at Goose Pond

Goose Pond contains an abundant population of fathead minnows, probably ideal prey for these small diving ducks. But in the past, the property lacked large trees with nesting cavities. That changed in 2015 when we erected two cavities as wood duck boxes. One box was placed at a wetland at Sue Ames Prairie and the other just west of the railroad tracks in the wetland south of the Kampen Road residence.

A hooded merganser nest was found on May 12 at Sue Ames Prairie. We checked the nest box on May 18th and the young were ready to jump out. Nine membranes from hatched eggs and one unhatched egg. This was the the first hooded merganser nesting at Goose Pond. Photo by Mark Martin

On May 12, 2016, Mark, Jim and Kathy Shurts, and grad student Heather Inzalaco conducted a big day count and Mark decided to check the nest box at Sue Ames Prairie. Mark slowly opened the side and could see an incubating female hoodie - what a surprise and a treat! Mark checked the box again on the 18th and nine young were getting ready for “jump day”. This was probably the first record for a hooded merganser nest at Goose Pond! 

Hooded mergansers have used this box every year since 2016. Last year the box contained a large clutch of eggs that did not hatch. We speculated that the female abandoned the nest, was killed, or that this was a dump nest and not incubated.   

However, one evening last July we looked out the large south window of the house on Kampen Road and saw a large brood of hooded mergansers! We were fortunate to watch them grow up. The brood started with 14 young and ended with twelve. The nest box near the brood was checked and many egg membranes and three unhatched eggs were found. Our guess is that both nest boxes were dump nests and only one was incubated. Late last month, Graham Steinhauer checked the box at Sue Ames and found a hoodie nest with the first egg laid on March 26th. 

Hooded merganser cuties, photo by Mick Thompson

When we put up our “wood duck” boxes, our goal was to attract wood ducks, and did we not expect to have nesting hooded mergansers. As of 2020 we still do not have any records of nesting wood ducks, but the hooded mergansers are sure making themselves at home!

A question that some visitors ask is, “Why aren't male hooded mergansers present in Columbia County after mid-April?” It is often mentioned when looking up information on hooded mergansers that after the hen begins incubating the male takes off. Most waterfowl biologists believe they head to wooded river systems and may travel long distances.

Special thanks to Mark and Jenny McGinley who have been erecting, repairing, cleaning out and monitoring 41 wood duck boxes for the past 11 years that at the Anderson Waterfowl Production Area (WPA), Jackson WPA, Otsego Marsh and Schoeneberg Marsh WPA/Erstad Prairie. All areas have high numbers of nesting woodies and hoodies.

Jenny McGinley checks on of their many wood duck boxes, this one at Otsego Marsh. Photo by Mark McGinley

In the past eight years, Mark and Jenny found 193 successful nests including 123 (64%) nests that were only wood ducks, 31 (16%) that were only hooded mergansers, and 39 (20%) that contained eggs of both species (dump nests). Both species can also lay eggs in the nest of their species. Mark and Jenny have found dump nests with up to 33 eggs! Large clutches usually do not hatch since a female would have a hard time incubating large numbers of eggs.

Hoodie females begin nesting at age two, usually lay a clutch of 10 eggs and incubate the eggs for 32 days while woodie females begin nesting their first year, usually lay a clutch of 12 eggs, and incubate for 30 days. It is easy to look at eggs and identify the species since hooded merganser eggs are large, white, thick-shelled and spherical contrasting to smaller, brown, thinner-shelled, oblong eggs of the wood duck. It is assumed that since wood ducks have a shorter incubation period that more wood duck eggs might hatch in dump nests that also contain hooded merganser eggs. We assume that if a female wood duck is checking out nesting cavities and finds a defensive hooded merganser already nesting that she would look for another cavity.

A wood duck box should have a solid predator guard to protect the eggs from hungry raccoons and other critters. Photo by Mark Martin

Consider putting up a nest box to attract a breeding pair. Attach a predator guard to keep predators from raiding eggs and young.”  Note that “wood duck box” blueprints work well for attracting hooded mergansers. Here are some instructions published by National Audubon on how to build a duck box. Some people use pine, but we recommend cedar for its excellent rot resistance. Be sure to add a predator guard as raccoons and other critters love to eat duck eggs.  

If you would like to see a brood of hoodies visit Schoeneberg Marsh Waterfowl Production Area adjacent to Madison Audubon’s Erstad Prairie, or MAS’s Otsego Marsh property south of Rio. The young are fun to watch diving, feeding and interacting.  

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