Owl breeding season has begun in Delaware

January 29, 2013 under CANR News

Heard any owls lately? Maybe you’ve seen one of these elusive raptors perched on its nest.

If so, please tell Jean Woods.

Woods is the curator of birds for the Delaware Museum of Natural History, one of the organizations supporting the Delaware Breeding Bird Atlas. The atlas is a five-year, state-led project to determine the area bird population and assess any changes since the last atlas, which was held 20-plus years ago.

Data gathering for the atlas was supposed to end in 2012 but there was a bit of a problem, says Woods, who sits on the project’s technical committee. Well, make that a big problem, at least when it comes to owls.

a winter owl in Delaware“We discovered that we didn’t have enough data on the nocturnal birds, especially owls,” she says. “We extended the atlas into 2013 to try to get some additional information.”

Woods is eager to hear from birders or, anyone, frankly, who has heard or seen an owl recently. It can be hard to distinguish the sounds – or sight – of many of the state’s shore and marsh birds. But it’s pretty easy to identify the calls of Delaware’s owls. Their hoots are distinct, and there are only a handful of species in the state.

This is a great time to listen for owls. The end of January marks the start of the breeding season so there’s lots of hooting out there. Owls call for a variety of reasons, including defending territory, communicating with their young, or, as is the case now, to advertise their availability as a mate.

“I can tell that the great horned owls are getting ready to nest,” says Jim White, associate director of land and biodiversity management for the Delaware Nature Society. “I’ve been hearing great horneds when I take the dog out for a walk.”

Delaware has four species of owls that are year-round residents – the great horned, barred, barn and Eastern screech, according to Chris Williams, a University of Delaware associate professor of wildlife ecology in the College of Agriculture and Natural Resources. The great horned owls are the first nesters; they’ll soon be followed by the barred owl and barn, and finally, the Eastern screech owls.

Three more species of owls – short-eared, long-eared and Northern saw-whet – are regular winter migrants to Delaware. A fourth species, the snowy owl, appears sometimes in what is known as an irruption, says Williams.

2013 isn’t shaping up to be an irruption year for snowy owls. But, on the plus side, there are a good number of Northern saw-whets here this winter, says Woods.

Four Delaware owls are considered to be “species of special concern” – the barn, barred, short-eared and long-eared, according to Wayne Lehman, a regional wildlife manager with the Division of Fish and Wildlife. Lehman bands juvenile barn owls every year, from May to July. Banding is easiest then because the fledglings are still on the nest and unable to fly.

The state has been banding barn owls since 1996. It also has established nesting boxes for owls in state wildlife areas.

“Banding provides valuable information on an owl’s life span, home range, nest site fidelity and migratory patterns,” says Lehman.

If you want to go on an owl prowl, set out after dark, especially on windless nights, says White. However, a few species aren’t strictly nocturnal. The Eastern screech – a short, pudgy owl with a large head and almost no neck – often exhibits a burst of activity just before dawn and at dusk.

To increase the chance of success, head to Port Mahon Road in Little Creek Wildlife Area, east of Dover. This is known as the No. 1 spot in the state to see owls — the short-eared owl likes to hang out here. And you won’t need to wait until dark – the short-eared starts hunting in late afternoon, when the sun is setting. This species is a migrant, so get to Port Mahon Road soon. By March, the short-eared will be returning to Newfoundland and other northern locales to begin breeding season.

How to help

If you see or hear an owl in Delaware let Jean Woods know so she can add this data to Delaware’s Breeding Bird Atlas. Contact her at 658-9111, ext. 314 or via email at jwoods@delmnh.org.

Not sure which species you’re hearing? Check out owl calls on All About Birds.

Learn more

On Feb. 10 there will be a program on “Owls and Other Winter Raptors.”

Look for great horned, Eastern screech, barn, barred, short-eared, and other owls on a day-long program with Jim White. The program has a good track record – owls have been spotted every year. To register, call 239-2334.

Article by Margo McDonough

Photo courtesy of Jim White, Delaware Nature Society

This article can also be viewed on UDaily.


UD researcher works to ensure Delaware’s wild turkey population proliferates

December 13, 2012 under CANR News

Wild turkeyIn colonial times, the Eastern wild turkey was abundant in Delaware. But by the late 1800s, wild turkeys were gone, eradicated by over-zealous market hunters and habitat destruction.

Usually, that’s the end of the story for a species.

Sometimes, however, species can be re-introduced to their original habitats. Such has been the case with the Eastern wild turkey, one of Delaware’s greatest conservation success stories, says Matt DiBona, a wildlife biologist with the Division of Fish and Wildlife in the state’s Department of Natural Resources and Environmental Control (DNREC).

In 1984, 34 Eastern wild turkeys from Pennsylvania, New Jersey and Vermont were given new homes in the woodlands of Sussex. In the 1990s, 100 wild turkeys from New York were released; in 2002 they were joined by another 33 birds from South Carolina and Virginia.

Throughout this period, turkeys in Sussex were captured and released further north to ensure distribution statewide.

This starter stock of 167 birds and their descendants have been prolific. “Today, Delaware’s wild turkey population is established and continues to spread,” says DiBona. “The population established so quickly that seven years after re-introduction we were able to offer a limited hunting season. We’ve continued to hold an annual four-week spring hunting season for gobblers.”

However, the Eastern wild turkey’s re-introduction to Delaware hasn’t been an unequivocal success story. About 20 years ago there was a population decline. It wasn’t widespread and numbers picked up after that. But Division of Fish and Wildlife officials realized the agency needs to better understand the population dynamics of wild turkeys.

Three years ago, the Division of Fish and Wildlife teamed up with Jake Bowman, a University of Delaware associate professor of wildlife ecology, to get a better handle on potential limiting factors affecting turkey production. “This is especially important because the number of turkey hunters is continuing to increase each year,” notes DiBona. “We thought it prudent to do research on these birds now to help provide some context for our harvest data.”

“The research project focused on hen reproduction, including the number of eggs laid and the survival rate of the poults (the babies), to determine reasons for population decrease,” says Bowman.

But you can’t figure out how many eggs a particular hen laid if you can’t distinguish her from the other hens – or find her, for that matter. That’s where turkey backpacks come into the story.

Seventy-six hens at Redden State Forest, near Georgetown, were equipped with little backpack transmitters. The transmitter, which is fastened under the hen’s wings with elastic cords, produces a radio frequency that can be detected up to a mile away.

During breeding season, Bowman’s grad students were at the state forest every day and at least several times a week other times of the year. Although Bowman’s teaching responsibilities kept him busy, at least once a week he participated in the fieldwork.

“You’re out there at all hours of the day and night, when it’s raining, when it’s hot,” he says. “But it’s great. I find research into native species such as the wild turkey more rewarding than study abroad trips I lead to places like Tanzania and Cambodia. There you’re just observing. But with research like this, you’re the one trying to find the answers.”

And Bowman and his team have found some of those answers. They’ve discovered that hens that nested on private land hatched more nests than those on public land, probably because of a difference in vegetation. They discovered that the average number of eggs per nest was eight, compared to the 10-14 eggs per nest seen in other states. Nesting success rates in Delaware are low compared to nearby states. In 2011 just 19 percent of the nests resulted in poults. The research team also discovered that fox and owl predation is a big problem, not only for the poults but for the mother hens.

There is good news to report, too. “Poult survival is greater in Delaware compared to other states, allowing for new birds to be recruited into the population,” says Bowman.

Although Bowman is wrapping up his project, the Division of Fish and Wildlife continues to track data in a variety of ways, including its seasonal Wild Turkey Survey.

“This is a citizen-scientist project; you don’t need to be a wildlife biologist to contribute,” says DiBona. “If you see wild turkeys on your drive to work or when you’re walking on a Sunday afternoon, we want to know about it.”

For example, Jason Beale, manager of Abbott’s Mill Nature Center, reported that he saw an adult hen with seven poults on Aug. 8. He’s participated in the survey for the past two years.

“I’ve lived in Delaware since 2006. I know that in 2011 and 2012 I saw more wild turkeys than in all the other years combined,” says Beale. “We see them in Lee Meadow here at Abbott’s Mill. Isaacs-Green Preserve is another good spot to see them.”

“Even when you don’t see them, you know they’re here,” adds Beale. “At overnight camps we can hear them gobble at dawn and dusk and we routinely see turkey tracks on the trails.”

How to help

To participate in the 2013 Wild Turkey Survey, contact Matt DiBona at 735-3600 or matthew.dibona@state.de.us.

Article by Margo McDonough

Photo by Bob Eriksen

This article can also be viewed on UDaily.


Stewart studies birds to understand trade-offs between reproduction, immunity

November 20, 2012 under CANR News

Does parenting take a toll on the immune system?

If you’ve ever been the parent of a newborn who demanded to be fed every three to four hours, your gut instinct tells you the answer is an absolute, unequivocal yes.

University of Delaware post-doctoral researcher Ian Stewart is conducting research to answer this question a bit more scientifically. His subjects – tree swallows – make human parents look like slouches. Both the mother and father tree swallow feed their hatchlings every five minutes, 12 hours a day.  (It should be noted, though, that their parenting gig is much shorter than ours — after 17 or 18 days the young leave the nest.)

Stewart is studying these small, migratory birds to better understand the trade-offs they make between reproduction and immunity. His research could potentially help scientists who study human biology better understand our own immune system and its stressors.

Stewart is part of a young but growing interdisciplinary field called ecoimmunology, which combines aspects of immunology with ecology, biology, physiology and evolution. He chose to focus his research on tree swallows and bluebirds because both are fairly tolerant of human interaction. “Some birds don’t like being observed but tree swallows and bluebirds don’t get stressed from being watched or handled,” notes Stewart.

There’s another very important benefit to working with these birds — since they nest in boxes, not up in the trees, they’re a heck of lot easier to catch.

Throughout the breeding season, Stewart catches the parent birds, injects them with a harmless antigen and releases them. Then, he re-catches the same birds a few days later to take blood samples and assess each bird’s immune response to the antigens.

“Some of the tree swallows work harder at parenting,” notes Stewart. “It may be because the bird has four hatchlings to feed instead of just three. Other times, the bird is simply more energetic at taking care of its hatchlings, regardless of brood size.”

“We’re monitoring the reproductive effort of the adults – mostly the rate at which they feed their nestlings – so that we can test whether the adults that are working harder produce weaker immune responses,” he says.

Stewart is conducting his research at Coverdale Farm Preserve, a 352-acre tract in Greenville owned by the Delaware Nature Society. The preserve already had 50 bird boxes in place last spring, when Stewart began his field work, and he installed another 50 boxes.

Now that it’s autumn, Stewart spends most of his time in the lab, crunching the data and performing immune assays on the samples he collected.  But earlier this season, he was at the preserve by 7 a.m. every day and after a full day of catching and observing birds, would head to the lab each evening to centrifuge the blood samples for storage.

“Prof. Mike Moore is overseeing my research and I had a grad student, Andrew Hydrusko, assist me, but I worked alone a lot,” he says. “So I enjoyed it when school groups passed by the bird boxes and there was time for them to learn a bit about my bird research. They loved to help catch the birds.”

“Ian’s work is quite interesting,” says Chris Williams, a UD associate professor of wildlife ecology. “One might think that having more offspring would improve your chances of passing off your genes to the next generation. However, if the parent’s health is compromised to make such an effort, natural selection may have something else to say about it. The evolutionary trade-offs between maternal health and maximum number of young ultimately produces optimal clutch sizes.”

So what’s the verdict — do parents shortchange themselves if they devote more resources to their offspring?

Stewart is still analyzing this year’s data and has another year of field research to go. But the preliminary answer, for tree swallows, appears to be yes. As for humans, he will defer to sleep-starved parents of newborns and let them have the final word.

Article by Margo McDonough

Photo by Danielle Quigley

This article can also be viewed on UDaily.


Spring means baby animals and a busy time for Delaware’s wildlife rehabilitators

April 19, 2012 under CANR News

Every spring, Cathy Martin cares for baby animals that wouldn’t have needed help if humans hadn’t “rescued” them, thinking these wild creatures were orphaned or abandoned by their mothers.

“Springtime is baby season for wildlife. If you encounter young animals, take a few minutes to assess the situation. Wild animals rarely abandon their young,” says Martin, president-elect of the Delaware Council of Wildlife Rehabilitators and Educators. In addition to this volunteer position, Martin is a fisheries biologist with the state Division of Fish and Wildlife.

More than 1,500 birds and mammals are brought to wildlife rehabilitators in Delaware each year. Many of these animals are in genuine need of assistance but others would have been better off left alone.

If a baby animal is bleeding or shows other signs of injury, put on gloves and use a towel or dustpan to push the animal into a box. Then call Martin or another local rehabber (see contact info below).

However, if the animal doesn’t appear injured, leave it where you found it. If a bird has fallen from a nest, either put it back in the nest or place it in a cardboard box with a hot water bottle to keep it warm. Give the parent a chance to retrieve it.  (It’s a myth that a parent won’t care for a baby animal if it has been touched by humans.)

Whatever you do, don’t stick around to see if mom is coming back, says Kyle McCarthy, a University of Delaware assistant professor of wildlife ecology.

“You may think that you’re well hidden or that you’re far enough away but a mother deer will smell you and a mother rabbit will see you,” says McCarthy. “She views you as a threat and won’t return until you leave.”

Even without the prospect of danger, some animals don’t devote much time to their newborns. In fact, mother rabbits usually only spend about five minutes at their nests each day.

In the world of ecology, rabbits are known as r-strategists. “Rabbits and other r-strategists give birth to lots of young but invest little parental care in these offspring,” says McCarthy.

Mice and other small rodents, insects, fish, some birds and bacteria are all r-strategists. The results of this laissez faire parenting style can be disastrous. “It’s not uncommon for a mouse to give birth to 20 babies in one season and only one survives through the year,” says McCarthy.

But since rabbits and other r-strategists breed like, well, rabbits, another brood of offspring will arrive before long. Rabbits begin giving birth in spring but have additional litters throughout the warm season.

Bears, deer, fox, some birds and humans are K-strategists. Compared to the r-strategists, fewer young are born in each litter. Deer less than one year old often give birth to just a single fawn; older does usually produce twins. Four kits in a litter is typical for the red fox.

K-strategist parents are heavily invested in the care of their young. After the red fox vixen gives birth, she doesn’t leave the den for about two weeks, relying on the male to bring her food.  The new kits weigh only about 3.5 ounces, are blind and totally helpless.

The parents bring live mice to the den once the kits are about a month old to help them learn how to hunt. The kits continue to live with their parents into mid-autumn.

Groundhogs, which are native to Delaware, usually have April birthdays. Not that you would know it.

“You aren’t going to notice any baby groundhogs running around until much later in the spring,” says McCarthy. “They aren’t able to leave the burrows and walk for a full month.”

McCarthy has a lot of respect for the volunteer work that Martin and other wildlife rehabbers do and he knows that their success stories are hard-earned.

Mortality rates vary for rescued wild animals raised in captivity but generally aren’t good. Baby rabbits are one of the hardest to raise while fawns have a much better survival rate. McCarthy’s own memories confirm this fact. His father was a bear biologist in Juneau, Alaska, and became the town’s de facto wildlife rehabilitator.

“People brought my Dad sick or abandoned porcupines, deer, squab, raptors and other animals,” recalls McCarthy. “As kids, we were always getting attached to the babies and naming them. One of my favorites, ‘Punky,’ a porcupine, was successfully rehabilitated back to the wild but many other animals died despite Dad’s efforts to save them.”

To locate the volunteer wildlife rehabilitator nearest you, go to this website and click on “contact us.”  You also can find info there on how to donate animal products or make a financial contribution to the Delaware Council of Wildlife Rehabilitators and Educators.

Ag Day, April 28

Love baby animals? At Ag Day you can see both juvenile and adult raptors and lots of baby farm animals, including calves and lambs. This annual, free community event takes place on the grounds of UD’s Townsend Hall in Newark. For more information, call 831-2508 or go to the Ag Day website.

Article by Margo McDonough

This article can also be viewed on UDaily


Colossal flocks of blackbirds are a common wintertime phenomenon in Delaware

December 8, 2011 under CANR News

If your holiday shopping takes you to Christiana Mall, time your drive for a half hour before sunset. That’s when you’re most likely to see a massive flock of black birds winging its way to Churchmans Marsh.

This flock of several million birds forms a solid black carpet in the sky; if it was earlier in the day, when the sun is higher, the flock would blot it from view.  The mixed flock consists of true blackbirds (red-winged, specifically) but also common grackles, brown-headed cowbirds and starlings.

“It’s an amazing spectacle,” says Derek Stoner, past president of the Delmarva Ornithological Society. “The sky is filled with birds returning to roost in the marsh after a day of feeding. You get the very best views of this super flock around the intersection of Route 7 and Churchmans Road — as long as you time it right.”

A flock of blackbirds so colossal that they block the sun sounds like something straight out of Hitchcock’s thriller, The Birds, but it’s a common wintertime phenomenon in Delaware.

“The unique combination of Delaware’s marshes and the surrounding agricultural lands are what make the state an attractive winter residence for millions of blackbirds,” says Chris Williams, a University of Delaware associate professor of wildlife ecology. “You’ll also see this winter flock phenomenon in New Jersey, coastal Virginia and North Carolina, and other coastal regions in the South.”

The Churchmans flock is one of about a dozen winter flocks in Delaware, according to Williams. Each morning the flock splits up and disperses in search of food, including such things as corn stubble or seedy grass. Depending on food availability, the Churchmans flock may travel to Chester County, Pa., or as far as Lancaster before returning to its nightly roost in the marsh.

Blackbirds only form super flocks in winter, says Williams. By March, the flocks will disperse to set up nests and begin breeding. Some of the birds in the super flocks are year-long Delaware residents; others migrate here from Canada and other northern latitudes.

As to why a bird would decide to hang out with millions of other birds each winter, scientists have several theories, says Williams. One possible reason is that a flock provides better protection from predators. Each bird in a massive-size flock doesn’t have to be quite as vigilant as it would be if it was flying solo.

A large flock also creates the conditions for “predator confusion.” For the same reason that fish swim in schools, birds fly in flocks. It can be difficult for a predator to pick out individual prey in large groups. “All the birds massed together create sensory overload for the predator,” notes Williams.

In addition, the dilution effect occurs when there is a large flock. Simply put, this means that the mathematical odds that a bird will get eaten are smaller when the flock is larger.

A large flock also promotes greater feeding efficiency because the birds share information about food sources. “Blackbirds are known to be great communicators,” says Williams.

Although Williams is awed by the Churchmans flock as it wings its way over his Newark neighborhood, heading out for food, he dreads the inevitable February day when 20 or 30 birds will drop down from the flock and take up residency in his backyard.

“I keep feeders up all winter long and enjoy seeing a variety of birds at the feeders,” says Williams. “But all of sudden, in February, a small group of blackbirds will break off from the large flock overhead, descend on my feeders and eat all the seed in minutes.”

“Even if I take the feeders down, the birds stick around,” adds Williams. “Blackbirds in the backyard are a sure sign it’s mid-winter.”

Article by Margo McDonough

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Department of Entomology and Wildlife Ecology adds Kyle McCarthy to Staff

June 16, 2011 under CANR News

Kyle McCarthy, assistant professor in the Department of Entomology and Wildlife Ecology, has traveled all around the world, from a childhood growing up in Alaska, to living in Mongolia, to conducting studies on Snow Leopards in Kyrgyzstan in the Tian Shan Mountains. Now, McCarthy finds himself living in the first state, having landed a job as an assistant professor with the University of Delaware’s College of Agriculture and Natural Resources.

McCarthy said that he is very excited to be a part of the College and of the Department of Entomology and Wildlife Ecology.

“Once I interviewed, one of the leading factors for why I came here was just the department. It’s a smaller department and there is a lot of collaboration. I feel like everyone works well together, there’s an openness with everybody, and it seemed like a very positive work environment where they still managed to get a lot of important research done. So I am excited about that.”

McCarthy also liked the fact that the wildlife major resulted in the students being able to become certified wildlife biologists under the wildlife society.

“It’s a great part of the program because mine didn’t lead to certification where I did my undergraduate work.”

Last spring, McCarthy taught a wildlife ecology and conservation class, and will add a wildlife management class in the fall and an ornithology lab in the spring.

Having received his bachelor of science in wildlife biology from Colorado State University in 2002, McCarthy went on to earn his masters and doctorate degrees in wildlife conservation from the University of Massachusetts Amherst in 2007 and 2010.

It was while doing research for his masters degree that McCarthy got to travel to Kyrgyzstan to evaluate monitoring techniques for Snow Leopard populations.

After returning to the University of Massachusetts Amherst, McCarthy conducted his Ph.D. research on the behavioral response of loons to human recreation on Lake Umbagog National Wildlife Refuge in northern New Hampshire.

McCarthy conducted his post doctorate work at the University of Florida where he worked with Florida panthers, assessing their behavioral response to recreational presence in Big Cypress National Preserve.

With all of his background in researching big cats, McCarthy said that he would like to develop a cat research program here at UD.

For now, McCarthy said that he looks forward to collaborating with his peers and educating his students.