By: Tim Freiday, Middle Run Project Coordinator

The group of DelNature staff and volunteers get ready to set off on the annual Bio-Blitz in Middle Run Natural Area.

On Sunday, September 3, 2017, Delaware Nature Society held the annual Bio-Blitz at Middle Run Natural Area. Although rainy at 6:00 am, the skies cleared by 7:00 am and it turned out to be a very productive day with over 200 different species of organism recorded. In the park, 88 species of birds were recorded. Some of the highlights were 20 species of warbler including a Brewster’s Warbler (a rarely seen hybrid), Nashville, Tennessee, Blackburnian, Cape May, and Black-throated Blue and Green Warblers. We had birds everywhere we looked, and had some great views of many. The girdled Bradford Pears continue to provide quality looks at some real quality birds, with American Redstarts, Tennessee, Magnolia, Black-and-white, and Chestnut-sided Warblers perching alongside much larger Brown Thrashers and Gray Catbirds. We also had a continuing Alder Flycatcher who “pipped” only a few times, and Veery were around today. Surprisingly, a nocturnal Common Nighthawk was also flying around in the late morning.  Check out the close-up Northern Flicker below!


All of the checklists for the day in chronological order are at the links below:

There have been some excellent photos of some of the fall migrant warblers being posted on the Middle Run flickr account by the likes of Hank Davis and Derek Stoner. You can check out those pictures by following this link:

Around a 100 insects were identified at least to the family level with the help of UD entomologists Ashley Kennedy and Adam Mitchell. Some highlights from the arthropod realm include a Spiny Oak Slug caterpillar, Hickory Tussock Moth, Locust Borer, Ornate Plant Bug, Cicada Killer, Green Darner and many more. There was a very bright Red Admiral butterfly which must have just emerged. Participants learned about the food web of arthropods in our area, and got a glimpse of how complex it really is. Middle Run has a healthy mix of arthropods, with many predatory spiders and insects signifying an abundance of herbivorous insects. No wonder the birds like it here so much! It’s also not surprising that there are so many insects given the diversity and abundance of plants at Middle Run. At least 50 different species of plants were identified today, with many beneficial native species. Some are very showy and are flowering right now, like the Evening Primrose. We only found a handful of reptiles and amphibians today, but there were some nice ones such as Black Racer, Garter Snake, and American Toad.

Hickory Tussock Moth

Hickory Tussock Moth

This year’s BioBlitz showed how truly special and utterly important Middle Run Valley Park is for the multitude of life that our region supports. From the local birds and insects to the long distance migrants that refuel here, to the people that come and unwind by taking in the natural world Middle Run is a true gem that we should all be grateful for. In appreciating the importance of Middle Run we are shown the importance of conserving natural lands everywhere, and we are called to action to protect our natural world.

This past Tuesday was the first Tuesday Morning Bird Walk at Middle Run of the fall 2017 season. These walks are free and open to the public, and Delaware Nature Society staff will lead them each Tuesday at 8am through October.  The walks are sponsored by New Castle County Parks.  Come join us as we appreciate birds and nature!

Happy Birding!

Story and photography by Jim White, Senior Fellow for Land and Biodiversity

Although I have seen it many times, I still always pause at the sight of an American Kestrel. This smallest, and most colorful, of North American falcons is a master of flight. It can soar high — or hover dragonfly-like over open lands while searching for prey, suddenly plummeting downward, swooping onto some unsuspecting meadow vole or large insect.

As part of our ongoing cavity-nesting bird box program at the Coverdale Farm Preserve, seven American Kestrel nest boxes have been installed over the years and are maintained and monitored each nesting season. This year the Delaware Nature Society joined with a nationwide program that focuses on increasing the American Kestrel population throughout the United States. Surveys have indicated that the species has suffered dramatic declines throughout much of its range. The lack of adequate foraging habitat and nesting sites are possible reasons for this decline. As part of this nationwide program, Delaware Nature Society Land and Biodiversity Management staff have monitored the nest boxes weekly this year for adult activity.

Because the open meadows of the Coverdale Farm Preserve are excellent habitat for kestrels, we were confident that at least one pair would take up residence. We were not disappointed. On March 13th we observed a male perched on one of the boxes. Three days later a female appeared. Throughout the rest of March and into mid-April the pair was frequently seen hunting over the meadows of the preserve, catching meadow voles and jumping mice. Finally on April 23rd we discovered three eggs in the box. A few days later there were five eggs.

Then on March 31st we observed five, some may say “cute”, nestlings.

On June 14th, biologists from the Delaware Division of Fish and Wildlife captured and placed identification bands on the nestlings, so that they could be identified if recaptured in the future. The team also took measurements to determine the age and health of the nestlings. We were glad to learn that all five nestlings looked healthy and had plenty of body fat. After “processing”, the nestlings were carefully placed back into their nest box, and the team left them to continue to grow and fledge (probably in a week or so).

So next time you visit the Coverdale Farm Preserve be sure to look up: you may just see one of these beautiful falcons!

P.S. Interestingly enough, on June 9th, staff discovered a second active nest with three eggs. We are hoping that this nest will also be successful.

By Sally O’Byrne, Trip Leader
Photos by Robert Tuttle, Jr.

A wastewater plant may not be the first place that comes to mind to look for birds, but many birders know the secret; They can prove to be quite good places to find gulls and waterfowl, often unusual in timing or species. Our local plant, operated by Veolia, is known as a great place for ducks which can be found in great numbers on the ‘polishing’ ponds adjoining the river.   Polishing ponds are the very last stage of a series of processes that separate solids from water and then cleans the water enough so it can be discharged to the Delaware River.

Aerial photo of Veolia Waste Water Plant

Aerial photo of Veolia Waste Water Plant

The wastewater that travels through sewers and enters the plant is called ‘influent’, and the first step is a mechanical bar screen that removes rags, paper, and other articles larger than a centimeter. Those screenings go to a landfill.   The ‘effluent’ (wastewater that exits) is then channeled into a grit chamber where the velocity is slowed down and the heavier grit, sand, and gravel settle out and are removed.

A large drum removes rags, paper, and other articles larger than a centimeter

A large drum removes rags, paper, and other articles larger than a centimeter

After leaving the grit chamber the wastewater enters a primary clarifier, where velocity slows again and additional suspended matter, typically organic, settles to the bottom forming a sludge layer. Greases and oil and other floating matter, rise to the top and form a scum layer.   Slow rotational scraper blades move the sludge to a hopper at the bottom of the clarifier and a skimmer on the surface directs the scum to another collector.

Empty and full clarifier

R to L: Empty and full clarifier


Now comes the secondary treatment; the wastewater flowing out of the primary clarifier goes into aeration basins where it is exposed to living organisms and bacteria that consume most of the organic matter in the wastewater. The water is bubbled to supply the microorganisms with the oxygen they need. In about 3 hours, the time it takes for the water to pass through the aeration tank, most of the organic matter has been consumed. (photo of aeration basin)

aeration basin

aeration basin

The secondary clarifiers receive the mixed liquor (wastewater and microorganisms) from the aeration tank. Here the scum on top is once again skimmed off and the activated bacteria that has settled to the botton is scraped into a hopper and then returned to the aeration chambers. The microrgasims will have increased through reproduction, so the excess are removed as sludge. The clear water leaving this basin now goes for Tertiary treatment. Here we have a group of Ring-billed Gulls enjoying the ‘fruits’ of Veolia’s efforts at the clarifier!

Ring-billed Gulls reaping the benefits of the clarification process

Ring-billed Gulls reaping the benefits of the clarification process

Throughout this phase, removed sludge is taken to an anaerobic chamber which gives off methane as it further digests the sludge. The methane is ‘flared’ and the final digested sludge is dewatered. It now looks and smells like humus and can be sold for non- edible application (e.g. golf courses).

A methane flair

A methane flair

Tertiary treatment happens in the large Polishing Ponds, the desired destination of avid winter birders. It takes about 3 days for the water to move through these ponds, where further settling and bacterial action take place. As a final treatment, the water is given a dose of bleach before it is sent into the Delaware River. The effluent entering the Delaware is tested daily for fecal coliform and other pollutants.   It is discharged through a pipe in the middle of the river at a depth of approximate 35 ft.

Waterfowl floating on the polishing ponds

This photo is from December 14, 2008, but shows the sorts of waterfowl number that are here in Winter.

We spent the final portion of our tour looking at a variety of ducks in the polishing ponds. In most places in New Castle County, the waterfowl have already migrated North, but here in this protected spot, we had a nice show.   On our trip, we had far fewer ducks than can be found in mid-Winter, but we had a nice variety; Gadwall, Mallard, Northern Shoveler, Ring-necked Duck, Lesser Scaup, and Ruddy Duck . We counted 23 species of birds for the day at Veolia Waterwater Treatment Plant – not bad for a place where most folks just want to hold their nose.

A Lesser Scaup duck floating in the polishing pond

A Lesser Scaup duck floating in the polishing pond

Ian Stewart, Ornithologist

One of the best ways to connect with nature is to monitor bird nest boxes. Regularly checking the contents of an active nest box lets you watch the whole breeding cycle unfold before your very eyes! It starts with nest building, progresses through egg laying and nestling rearing and then (hopefully) ends with the young birds successfully leaving the nest.


Using an mirror to count Bluebird eggs

The Delaware Nature Society has a team of eager volunteers who monitor over two hundred boxes spread throughout several properties and every year brings more data and surprises. Our most common occupants are Tree Swallows, Eastern Bluebirds and House Wrens but most years we attract a few Carolina Chickadees, Carolina Wrens and Tufted Titmice. One year we had a White-breasted Nuthatch use one of our boxes – who knows what species might show up next?!

Chickadee on nest

Opening this nest box revealed a Carolina Chickadee sitting tightly on a nest. In these cases we leave the bird alone and retreat.

Checking boxes lets you see for yourself the many differences between each species in the way their nests are built, the shape and color of their eggs, and the appearance of their nestlings, as well as the nesting quirks of different birds. Did you know for instance that House Wrens often add spider cocoons to their nest, probably because the spider hatchlings eat arthropod pests mixed in among the nest lining?

Wren nest with spiders

House Wren nest lining dotted with spider cocoons

Our boxes remain in place year-round and provide winter refuges for both welcome and (slightly) unwelcome guests. Eastern Bluebirds roost in our boxes overnight during the winter, presumably to help them stay warm, and sometimes bundle together in the same box. Last winter one of our boxes at Coverdale Farm Preserve had an enlarged entrance hole and was filled with acorns from the huge old Red Oaks that line the driveway. This was probably a squirrel using the box to cache a supply of acorns to chomp on if a sudden snowfall made food hard to find.

chewed box


Mice also like to spend the winter in our boxes so we have to bump them out to allow the birds to nest. Can you spot the two mice jumping out of the box?


We have been cleaning out our boxes to get them ready for spring and the birds are checking them out already so nesting isn’t far away! We can always use an extra person or two to help monitor nest boxes at Coverdale Farm or the Red Clay Reservation near Greenville, or Abbott’s Mill near Milford, so if you want to get involved just give us a call on (302) 239-2334. Boxes only need to be checked once a week and monitoring them makes a great excuse for talking a walk on a summer evening or weekend at these beautiful sites. All of our data are submitted to Cornell University’s ‘Nest Watch’ scheme so we are contributing to science as well as simply enjoying nature.

If you’d rather put up your own nest boxes why not join our upcoming program (April 27th at Ashland followed by a field trip to Coverdale on April 29th) to get advice on how to design and position boxes in order to attract nesting birds to your property? Having birds nest in a box you built yourself is a tremendously satisfying experience that may be repeated for many summers to come!

Tree swallows on box

A pair of excited Tree Swallows start building their nest in a brand-new box