The majestic birds on the lakes

© Joe Herlong | Dreamstime.com

By Mark H. Stowers

Great Blue Herons and Great White Egrets are often described as mysterious and majestic – so much so that the National Audubon Society uses the Great White Egret in flight as its symbol. These common wading birds are found in wetland areas from South America to Canada and they're quite prevalent in Michigan and across Oakland County.

Several other types of herons, egrets, as well as bitterns, are found in the Mitten State and are in the Ardeidae order of birds that include the Least Bittern, American Bittern, Little Blue Heron, Tricolored Heron, Reddish Egret, Snowy Egret, Yellow-crowned Night-Heron, Black-crowned Night-Heron, Green Heron, Great Egret, Western Cattle-Egret and the Great Blue Heron.

The Great Blue Heron and the Great Egret are two of the county’s most recognizable birds. The Great Blue Heron is a tall bird that enhances its appearance with long legs and neck, accentuated by a prominent bill and a distinctive blue-gray color. The adults feature a black stripe over their eyes. As they migrate from North America south to Central and South America, they thrive and nest in both freshwater and saltwater environments, from marshes to rivers to lakes, but they particularly enjoy brackish settings.

Francie Cuthbert, a professor at the University of Minnesota who works for the Minnesota Department of Fisheries, Wildlife and Conservation Biology, notes that the two species are well-known.

“The Great Blue Heron has a long history in the state of Michigan. They've been here since the 1800s or before,” Cuthbert said. “They're very native to the state. But the Great Egret is a species that's been moving into the state and moving a little bit further north, with the biggest concentrations mainly in the lower peninsula and mainly in the lower half of the state. They've been slowly moving northwards. I've seen some in the Upper Peninsula and they can do very well to as long as they've got good feeding conditions.”

With her work she’s been able to keep a close eye on the population as well.

“I worked on various contracts with the U.S. Fish and Wildlife Service to census colonial water birds in the Great Lakes,” Cuthbert said. “I've led the last two census efforts. I do know water birds in the Great Lakes. The Great Egret and the Great Blue Heron are species of birds that the public recognizes. When they see it, they may not know the exact name, but the public finds them important.”

She explained the visual allure, saying, “The egret is gorgeous because its feathers are a really intense white. It has special plumes during the breeding season and then the great blue is just big and often stands where people can look at it. It spends a lot of time just standing in the water looking for fish to swim by.”

The birds are federally protected since there are no hunting or trapping seasons, and they are linked to the first Federal Act ever established to protect a species. This is all due to 1800s-era fashion.

“Egrets were being killed in large numbers for their feathers. People were killing them at their colonies in Florida, literally by the thousands. And then they were being shipped around the world. And they were used to make very fancy hats for women. The Great Egret was almost exterminated from the U.S. because of that pressure.”

Once recognized by the public and brought to the attention of the United States Congress, the Lacey Act was enacted and signed into law in 1900 to prevent the sale of protected wildlife, wildlife parts, fish and plants. The act has been amended to include additional protected wildlife and plants and was last updated in 2008. The Migratory Bird Act of 1918 was also established to protect these species and others. This act provides comprehensive protection for migratory birds, including their nests, eggs and breeding habitats. It is illegal to kill, harm, or harass these birds or disturb their nests during the breeding season.

In human terms, the two birds are “snowbirds” as they migrate from Michigan in the winter to warmer climates in the south, just as many humans do. Each returns to familiar settings and the same homes, nests and rookeries (a collection of nests high in a clump of trees) year after year.

“The male comes back first. Returning to their colony sites is very traditional. They prefer to nest in colonies, up in tall trees. But I've also seen Great Blue Heron nests on the ground, which is always kind of shocking. And it's rare, but they can. And they will nest around people. They're not necessarily real skittish and solitary. There's some in urban areas, like urban parks.”

She explained the nests are quite substantial and only need minor repairs when the birds make their return.

“They tend to go to their former nest but they may decide to take another nest. And then they'll build up and add more sticks,” she said. “The nest can be a pretty good size over a number of years as they keep using it.”

She also explained the two species will nest together.

“They are attracted to each other in the sense that they do like to nest in colonies. Part of that has to do with the habitat. If the habitat's right and the trees are right. And they're going to be nesting near where there's a good food resource. They have some protection nesting as a group. They can give alarm calls if there's a problem,” Cuthbert said.

When it comes to eating, the birds aren’t picky. Fish seem to be the foundation of their own food pyramid, with plenty of other species thrown in. Pretty much if they can catch it and stab it with their beaks, they swallow whatever it is whole.

“They can eat pretty good-sized fish, and you know most of what they're feeding is not really game fish, but they feed a lot on rough fish in shallow water like carp and suckers. They will eat small turtles and they'll eat snakes,” Cuthbert said. “I've seen them eat water snakes, and they'll go into more grassland areas and feed on small mammals. There are even reports of them feeding on muskrats. The Great Blue Heron’s diet is described as ‘opportunistic carnivores.’ They'll pretty much take what comes their way.”

She noted they will also raid other bird nests and feed on eggs and young birds.

“Some people would say that's their dark side,” according to Cuthbert.

The two species have predators themselves, Cuthbert explains.

“Two predators I know can seriously threaten an egret or a Great Blue Heron colony - one is the Great Horned Owl, which sometimes nests within a colony. They may place their nest in the center, and when the birds are hatching, they can take the young. The other predator is the raccoon. I had a student studying blue herons in Minnesota, and people kept reporting that the birds were deserting. They appeared to be nesting, and everything seemed to be fine, and then they'd disappear. He put cameras in the nests and lo and behold it was raccoons that were going up the tree and grabbing young and eating them and they were causing this colony to fail.”

Sean Zara, a biologist with Oakland County parks division, can attest to the opportunistic diet of herons.

“Birds don't chew. The herons don't rip apart their prey, they swallow it whole while it's potentially still alive, or they smash it around until it stops moving. But they can swallow surprisingly large animals,” Zara said. “I’ve seen photos of herons stabbing and eating small alligators in the south.”

In describing their benefits and detriments to the ecosystem, Cuthbert explained, “No wild native species is truly a disadvantage to the ecosystem. They're part of the ecosystem. But there are some things that humans perceive as being negatives. Both the Great Egret and the Great Blue Heron nest in colonies, and if that's near someone's property, they can be noisy, and they will, over time, kill the vegetation because they can be so densely packed, and their fecal material has a lot of nitrogen that falls to the ground and can damage vegetation.”

Zara has seen plenty of both species in Oakland County.

“They build their nests in large trees, communally, presumably, because it's safer for predators, they like to be out over the water, not always,” Zara said. “They're large birds, and they generate a lot of poop and so once one of those communal nesting sites starts going, the ground underneath the tree is completely whitewashed and commonly the trees eventually die from it. It's just too acidic. They’ll continue to nest in those dead trees as long as they stay standing.”

Looking at their benefits to the ecosystem, Cuthbert explained that just seeing the two species gives a quick insight into the health of the surrounding environment.

“They can't exist if the water quality is not good or if the habitat is lost. They’re like a sentinel. If you're seeing Great Blue Herons and Great Egrets in a habitat, it means that they're doing well and the quality of the aquatic system is healthy,” she said.

With federal protection and few predators to the adult population, the birds can live nearly three decades.

“Both species can live to be typically around 15 years old. That's fairly old, and there are some records of both species living to be about 23, 24 years old,” according to Cuthbert.

Cuthbert described the Great Blue Heron as the largest in the heron family in North America with a wingspan up to seven feet. The tall and majestic animal doesn’t move much – or so it seems.

“They spend most of their time not doing much or appearing to do much. They spend most of their time looking for food or waiting for food to pass near them. Because they're a sit-and-wait predator. They stalk them. They're going to stand there all day and just keep fishing.”

The birds can become a nuisance and a problem for fish hatcheries and commercial fishers with ponds as the birds use them as their personal buffet lines often costing fish farmers thousands of dollars in losses – especially in southern states. It is illegal to shoot herons and egrets without a permit from the USFWS. A permit can be obtained by commercial fish farms to augment their on-going nonlethal harassment programs.

Electronic devices that play bird alarm calls can repel herons and egrets but they may be disruptive to surrounding businesses and residents. Propane cannons under roost trees can also be effective.

Kylie McElrath, Conservation Manager, Michigan with the Audubon Great Lakes, was a biologist with Ducks Unlimited prior to this position. She detailed her work with Audubon and with the two bird species.

“Audubon Great Lakes is a regional office of National Audubon Society,” McElrath said. “We focus on five states of the Great Lakes Basin, but National Audubon Society primarily focuses in the U.S. We also span a hemispherical approach with work across North America and even down into South America because the birds migrate and they're utilizing habitats outside of just the U.S. and North America.”

With hundreds of birds in the Great Lakes basin, McElrath estimates the number at 450 species. In looking at egrets, herons, and bitterns, she explained, “We can find about 12 species of herons, egrets and also bitterns. Egrets and herons are in the family Ardeidae, which includes herons, egrets and then allies that are known as bitterns. And they're essentially herons, but they're more secretive. So, they're what we refer to as secretive marsh birds, but they're in that same family.”

Even though the bird populations are listed as “not of concern,” the loss of habitat from Canada to South America does put pressure on them.

“Great Blue Herons and Great Egrets are pretty commonly found and pretty widespread, but species such as the Least Bittern and the American Bittern are species that we do have some more conservation focus on because they are much more dependent and reliant on these high-quality wetland habitats,” McElrath said. “Bitterns are facing the threat of habitat loss. We're losing our wetlands at a pretty significant rate. And that is, in turn, threatening those bird species.”

Those habitats are under threat due to urban sprawl, pollution and nutrient overload in those ecosystems. In looking at the species, McElrath explained the birds are separated in different ways.

“Egrets are actually more of our white heron species, and herons are those in that family that have the darker plumages, so they're really kind of named more based on plumage and a little bit from size,” she said. “Egrets are typically a little bit smaller in size than our herons but our Green Heron is actually one of the smallest of the family. Behavior-wise, they're pretty similar, so they will nest in colonies, often referred to as rookeries or heronries, and so they'll build platform nests in shrubs or trees over trees in water or near water bodies. You can often find many or a few of these species in a same rookery. They’ll be in groups, but species like the green heron and the bitterns are solitary nesters. So, they actually will not nest in these colony formations. Green Herons will be often solitary in trees near water or dense shrubs.”

When nesting, the incubation period ranges from 23-28 days for larger species and 17-21 days for smaller species with anywhere from two to seven eggs being layed. Those hatchlings will usually fledge anywhere from four to seven weeks.

“Mid-May is when we're going to start seeing them come back and then we'll start seeing them leave in the late summer or early fall, so August, September time frame,” she said.

A sign of an early spring are herons and egrets returning to Michigan in March and even February. The mating habits include “not typically mating for life, but they're what we refer to as seasonal monogamous, so they will remain with the same mate for a particular breeding season, but then the next breeding season, they'll likely be finding a new mate, but they will stick around with that mate for the particular breeding season, and they will help with care of the young. You can find them breeding in the whole span of the eastern U.S., Florida up to Michigan. What we have breeding in Michigan are going to be our Great Blue Herons, our Great Egrets, our Green Herons, our Black-crowned Night Herons, and then our Bitterns.”

When looking at their diet and eating style, McElrath said, “They'll stab something and make it stop. You'll see them kind of toss a fish up and swallow it whole. And fish is their primary food source, which is why they have those long dagger-like bills to help either stab or catch those fish. They're what we refer to as carnivorous wading birds, so mostly feeding on fish, but they will also feed on other vertebrates or even large invertebrates that are found in these water bodies or wetlands. Frogs, tadpoles, salamanders, aquatic insects and larvae, even crustaceans like shrimp or crayfish. Some of our larger species, like our Great Blue Herons, might even be feeding on small mammals if they're available in the areas, or even on occasion, reptiles, small birds, or snails. They have a pretty wide range of diet.”

In her field work in restoring habitats, McElrath noted artificial structures for herons, egrets and other birds will be added to “help create a diversity of structural habitat. Most of the work we're doing is conservation, restoration, enhancement, and protection of coastal wetlands around the Great Lakes Basin. And so that sometimes might look like a larger restoration project where we're restoring a wetland or we're doing an enhancement project where there's an existing wetland that just needs some modifications to enhance the quality of it. And in all of the conservation work that we do within wetlands, we're really focused on breeding marsh birds, but we're also focused on creating a diverse habitat within these wetland ecosystems so that it's benefiting a large suite of birds.”

Some of the wetland work includes adding coarse woody debris that can help some species nest. A gradient of habitat is created so that there's that marsh habitat but also a gradient up into shore, into the wet meadows, and potentially even shrubby vegetation, which can help breeding herons and egrets.

“We do focus on as much diversity and if it seems fit for a particular project, we might do an island in the wetland, and that could offer opportunities for egrets and herons,” she said.

Private landowners can also work to protect and enhance habitat for the bird species.

“Depending on the size of property the most important thing is stewardship,” McElrath said. “For lake owners and folks to be general stewards of the water bodies and support the health and the quality of the lake that you're living on, or other water bodies that support the Great Lakes. And advocate for policies that can help support these ecosystems as well. That's where you're likely to make the biggest impact is just being a steward of the lake and to help advocate for policies that can help protect our wetland ecosystems but also keep our lakes clean.”

Scott Tiegs, a professor in the Department of Biological Sciences at Oakland University and the principal investigator of the Aquatic Ecology Lab For the past 15 years, has led a tropical field ecology course that has involved over 200 students in countries such as Guatemala, Costa Rica, and Ecuador. His research focuses on the human impacts on aquatic ecosystems, especially invasive exotic species and the effects of human activities on carbon cycling through changes in organic matter decomposition.

"As wading birds, egrets and herons require shallow-water habitats like shorelines and lake margins, but these areas are all-too-often impacted by development,” Tiegs said. “People love to live close to the water of course, but we can minimize our impacts by refraining from using shoreline protection structures such as riprap, seawalls, etc."

Nancy Seefelt, an ecologist, evolutionary biologist and professor and alumnus of Central Michigan University and has been teaching since 1997. She earned her Ph.D. at Michigan State in 2005.

“I teach courses in ornithology and avian ecology and have more experience with the egret and heron’s little cousin, the Black Crowned Night Heron. I work primarily with the colonies that are on the Great Lakes themselves and when we take a look at the Great Lakes, the Great Egret numbers have been increasing over time but they started very, very small, so that's not that surprising.”

She noted both Great Blue Herons and Black Crowned Night Herons have been declining in terms of their breeding population but not due to any one main problem.

“There's lots of habitat changes. There's changes in the food webs. There's not a smoking gun. Climate change is thought to be a big issue as well. Lake levels are changing, so no one really has a one-word answer or even a two-word answer as to why there are lower numbers,” Seefelt explained.

The Black Crowned Night Heron is much smaller. In fact, there was a colony nesting at the Detroit Zoo near one of the concession stands for a while. However, they're a wild colony that moved into the zoo due to the abundance of free food. They will eat just about anything, so they steal food from the different enclosures,” Seefelt said. “Their nests are smaller, but they nest in trees or shrubs and in colonies, just like Great Blue Herons do. They tend to be a bit more secretive. They're a really interesting species because, even though they're not very common here in Michigan or are declining in numbers, they're considered a species of special concern. They can actually be found all over the world, except Antarctica.”

Jen Owen, associate professor at Michigan State University in the Department of Fisheries and Wildlife, studies bird migration, bird diseases and runs the Michigan State Bird Observatory in Bath Township. She also leads the Corey Marsh Ecological Research Center, where more than 6,000 birds, including 87 species, are banded each year to track them and gather data.

“I've been working with birds since I got out of school, undergrad, which was about 30 years ago,” Owen said. “Herons and Egrets are so unique in the way they fly, and they're sort of that characteristic or sentinel. Great Blue Herons, I feel like you see pretty much everywhere. It's not like there's certain areas that maybe have higher concentrations than others, but with Great Egrets, you typically are going to see a lot down near Detroit. And then also Shiawassee National Wildlife Refuge up by Saginaw. You can definitely see them at Corey Marsh. In the fall, we get large flocks of Great Egrets, which is amazing. It's beautiful.”

She noted that both species “love wetlands with shallow water because it's easy to get prey. And they love crawfish. We've been trying to see how many we're getting, because we're getting more egrets and herons than we ever have in the summer.”

Even with so many birds being banded, “There's not a lot of banding on wading birds. I know there are folks that are doing that down in Florida. They use what's called rocket nets. We do this sometimes with waterfowl, too, or with shore birds. It's a net that literally shoots up and over them because it's less harmful to the bird. Whereas certain birds like cormorants, when they're on the ground, we use leg-hold traps. There are all different ways to catch birds depending on the bird itself. We use mist nets, like netting, for songbirds.”

The Great Blue Heron and The Great Egret, two majestic and mysterious birds that call Michigan home. ­­­­