The Nature of Delaware

A male Red Fox at Coverdale Farm stares intently as the late afternoon sun makes his fur glow.

The reports are flying in to the nature center: foxes are everywhere!  During the past couple of weeks, folks are seeing all sorts of Red Fox activity and some very interesting behaviors!

Last week I saw a pair of foxes mating in a field, a persistent male fox trying to haul away a dead Canada Goose, a fox trotting along with a massive chunk of meat clamped in its jaws(see photo), and a battle between foxes that involved lots of snarling and mad dashing about.

A Red Fox carts off a big chunk of meat(deer?) across a field.

What’s all the fox fuss about? Well, the explanation is both easy and difficult.  Right now is the peak of the mating season for Red Foxes– that’s the easy answer.  Why we are seeing so much daytime movement of foxes is the important question.

Foxes are typically crepuscular, meaning they are most active at dawn and dusk.  Duing these periods of low light, a fox’s prey is also highly active– the mice, voles, shrews, birds, and other small animals that make up the bulk of this canine’s diet.

A fox's ears help it to pinpoint the locations of sounds and potential prey.

With cold weather upon us and higher caloric demands, foxes are ranging far and wide in search of food.  The rigors of the mating season also mean foxes are spending more time protecting their territories, which may be several hundred acres in our more rural areas or as small as a suburban neighborhood.    Foxes have taken readily to suburbia, with its surfeit of food in the form of garbage, rodents, pet food, roadkill, and even small pets (yes, your housecat is considered potential food by Vulpes vulpes).

A Red Fox blends in to a warm-season grass meadow at Burrows Run Preserve.

Have you seen any foxes lately?

A beautiful portrait of a pair of Red Foxes at the DuPont Environmental Education Center in Wilmington. Photo by Jim White.

One of the most dependable places to watch foxes lately is the new DuPont Environmental Education Center on the Wilmington Riverfront, where a resident pair of foxes is often seen hunting around the edges of the marsh and near the nature center.  Be sure to visit and search for these crafty canines!

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By Jim White, Associate Director, Land and Biodiversity

Installing nest boxes in your yard is a great way to increase your bird viewing enjoyment.  My favorite such box that I recommend for anyone that has a yard near a woodland is an Eastern Screech-owl box.  Eastern Screech-owls are one of our most common owls and are found near most woodlands and woodlots in our area.  These boxes simulate tree cavities and Screech-owls use them for diurnal roosting and/or nesting. 

A red phase Eastern Screech-owl peers from a backyard bird box. Photo by Jim White.

Most of my observations of Screech-owls in boxes are of roosting birds.  They often can be seen poking their head out of the box while perched in the entrance hole in late afternoon or just before sunset.  Boxes can by placed just about anywhere but should be at least 100 feet from areas of high human activity.  I recommend facing the box toward a good viewing spot like a window that you often look out.  Also, I like to face the box west toward the setting sun, so they can peer out and warm up late in the day.  This will make it more likely that you will see the owl that comes to roost in your box.  In my experience, Eastern Screech-owls only uncommonly nest in boxes.  Nesting begins in mid-March or early-April, so if you see an owl in the box in spring it may well be nesting there.

Set up your box so that you can easily see it from a window in your house. Photo by Jim White.

Screech-owls require relatively large boxes.  These boxes measure 12-15 inches high with floor dimensions about 8 inches square.  The entrance hole should be 3 inches in diameter.  The box should be placed on a tall, 10-15 foot pole preferably made of steel, but wooden posts can be used.  Predator guards are recommended because they keep mammals and snakes out of the boxes.  The boxes can be home-made or, if you are like me and lack time and woodworking skills, purchased at a local bird stores or on the internet.  Construction plans can be found here.  Screech-owls will also use larger boxes intended for nesting Wood Ducks.

Sometimes Eastern Screech-owls nest in bird boxes. These three chicks were raised in a box at the Delaware Nature Society's Burrows Run Preserve. Photo by Joe Sebastiani

Good luck with your project.  If you have any other questions you can email me at jim@delawarenaturesociety.org.  If you are interested in the owls in our area, look for my future blogs in which I will profile each of Delaware’s eight owl species.  Also, join me on my annual field trip to try to find all eight species in one day.  This year, the Owls and Other Winter Raptors trip is scheduled for Sunday, February 14, 8am to 7pm.

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By Jason Beale, Manager, Abbott’s Mill Nature Center

Most people have heard the term “cold-blooded”, but our perception of the word and how it applies to wildlife are often quite different.  The recent cold spell that kept furnaces working overtime brought out a surprise at Abbott’s Pond.  A Red-bellied Cooter (Pseudemys rubriventris) has been surface basking this winter.  During the initial sighting on January 4, day temperatures were barely above freezing and the nights were well into the teens.  Ice formed and briefly covered the pond.  Yet, the turtle remains a daily sighting amongst the backdrop of wintering Ring-necked Ducks and other waterfowl.

The Red-bellied Cooter's head is visible in the middle of the photo. Photo by Jason Beale.

A warm-blooded or endothermic animal produces its own heat through internal processes while cold-blooded or ectothermic animals obtain the majority of their heat from an external source.  Yet, there I was, cold despite my layers of clothes observing an active reptile in a pond whose waters were just above freezing.  The turtle was indeed sluggish as it turned and dove, but it certainly challenged my notions of warm and cold blooded. 

Basking Red-bellied Cooter are a common sight at southern Delaware millponds from spring to fall. Photo by Jim White.

Red-bellied Cooters are generally active from March-November and are habitual baskers along with the Eastern Painted Turtle.  You may be familiar with these turtles and their large, rounded carapaces (top shell), as they sit on logs in warm weather.  The younger turtles have reddish markings, but become melanistic (darker) with age and older specimens may appear almost black. 

Red-bellied Cooter in Abbott's Mill Nature Center Wet Lab. Photo by Jason Beale.

There are published reports of Eastern Snapping Turtles active under ice in the winter, but I found no mentions of winter Cooters.  Jim White, Delaware Nature Society’s Associate Director of Land and Biodiversity and co-author of Amphibians and Reptiles of Delmarva,  said, “Since they are completely herbivorous as adults, they don’t require much energy to feed.”  Therefore, they are able to meet their energy needs by surface basking and foraging for aquatic plants.  However, typical winter behavior for aquatic turtles is to hibernate by burying themselves into the soft mud at the bottom of ponds.  Despite having lungs and being air-breathers, they are able to exchange gases and oxygen through their skin, surviving for months.

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For the last four days, we have seen several Bald Eagles here at the DuPont Environmental Education Center in Wilmington, including two adults and a 2-3 year old juvenile. The juvenile looks considerably different than the adults, and is primarily brown with white mottling and without the familiar white head and tail. The white on the head and tail does not begin to appear until the eagle’s 4th year of age, and by its 5th year it has developed full adult plumage.

Immature Bald Eagle. Photo by Jim White

These may be local breeding residents, as three Bald Eagle nests are found nearby, but there is no way to tell for sure.  One pair nests at Churchman’s Marsh, another near New Castle, and a third at Hoopes Reservoir. They could also be migrant winter residents, as many Bald Eagles travel southward from the northern U.S. during the winter searching for an open water source that is not frozen over. Some stop in our region.

Adult Bald Eagle. Photo by Jim White

Delaware’s nesting Bald Eagles are either close to egg laying, or they have already started incubating their eggs.  Personnel from the Delaware Natural Heritage and Endangered Species Program, Division of Fish and Wildlife, will begin surveying for reproductively active nests next week.  From a small airplane, they fly over known nesting areas to search for incubating birds, and will keep track of the nests this way through May to see which ones end up successfully raising young.  In 2009, there were 36 successful Bald Eagle nests in Delaware.  If you think you’ve found an active Bald Eagle nest, Natural Heritage wants to hear from you.  You can call them at (302) 653-2880 to report your find.

The Bald Eagles at DEEC spend much of their time sitting in the trees growing on the dike along the south side of the marsh.When the eggs hatch and it is time to start feeding young, hopefully we’ll get to see more fishing activity around DEEC.  Pay us a visit and stand on one of the elevated balconies to search for the local Bald Eagles.

Bald Eagle sitting in a tree on the edge of the marsh at the Dupont Environmental Education Center. Photo by John Harrod

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By Joe Sebastiani, Members Program Team Leader

You know it is a slow morning of birding when one of the participants says, “At least we had a good breakfast.”  Yes, indeed.  This morning, Michele Wales and I led the Birding and Breakfast program at Coverdale Farm, she made the breakfast, and I led the bird walk. 

Program participants enjoyed a wonderful fruit and quiche breakfast, made from Coverdale Farm chicken eggs.

Our group of birders finally happy to see something up close sitting still!

Cooper's Hawks don't eat chickens, but eagerly catch smaller birds, like House Sparrows.

It was a great day to be outside to walk the farm and preserve and not be wet, wind-blown, and freezing.  We saw 29 species by the end, which isn’t too bad.  Join us on our next Birding and Breakfast program at Ashland Nature Center on February 12 in conjunction with the Great Backyard Bird Count.

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By Sally O’Byrne, Teacher-Naturalist

Last Wednesday, I attended the weekly bird survey at the Delaware Nature Society’s Flint Woods Preserve near Centreville.  Mike Weaver, a Land Manager who works there, joined me on the walk.  We were impressed with the amount of water that had seeped into the ground with this year’s excessive precipitation.

Mike Weaver stands by a small stream at the Flint Woods Preserve.

Another unusual feature was how last night’s ice formed in areas with saturated soil that didn’t have standing water.  Along a path that was damp, the leaves were pushed up by the ice.  Looking closely, we saw that the ice was in the form of miniature columns. 

The ice column was as tall as my pen above ground!

When we plucked an ice column from the mud, it was obvious that the ice had formed from the ground up and had “leached” mud from the dirt into the columns by some sort of capillary action.  Some of the columns were 6 to 8 inches high.  This was a new find for both Mike and I.

We plucked an ice column from the ground for a close examination.

An ice column measure against Mike's arm.

Epilogue (By Joe Sebastiani): What Sally and Mike found was a form of Frost Heave.  This usually happens in moist, fine grained soil, like silt, and it is not just simply due to freezing and the associated volume expansion of water turning to ice.  Vertical displacement of soil from Frost Heave is far greater than the volume expansion associated with water freezing, which is about 9%.  Why does this Frost Heave occur then?  Simply put, the column of ice is drawing in liquid water trapped in surrounding  small pores of soil.  This happens as the ice purges itself of tiny foreign particles, raising the ice upwards while it sucks in surrounding water from the soil.  This liquid water is added to the column as more ice.  So, the ice moves upwards and grows at the same time.  (This is according to Wikipedia, so you can look it up yourself if you really want the dirt, uh, ice on this phenomenon). 

Frost Heave occurs when you have the following conditions…freezing temperatures, a supply of water, and soil that has the ability to conduct water, a high affinity for it, and is saturated.  Clay soils are not very water conductive and sandy soils have a low affinity for water.  Silty soils are the middle ground (no pun intended), and tend to be where Frost Heave occurs.

Now, go out there and see if you have some Frost Heave where you live.  Watch out!  Frost Heave can damage plant roots, cause erosion on steep slopes, and even crack concrete as it pushes up the soil!

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