Delaware

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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

Evelyn Williams, Certified Naturalist and Volunteer Guide

Joe Sebastiani, Ashland Nature Center Manager

During the fall and winter months one of our the most frequent sightings in the Russell W. Peterson Urban Wildlife Refuge marsh is of Red-winged Blackbirds sitting on grasses or making short, low flights in small flocks from plant to plant.  Male red-winged blackbirds have black, glossy feathers with red and yellow shoulder patches on their wings. Females are a streaky brown color.

The male Red-winged Blackbird is glossy-black with a red and yellow patch on the wing called an epaulet. The female is streaky brown, and can be mistaken for a sparrow. Note her long, pointed bill, which a sparrow would not have.

The male Red-winged Blackbird is glossy-black with a red and yellow patch on the wing called an epaulet. The female (behind the male in this photo) is streaky-brown, and can be mistaken for a sparrow. Note the long, pointed bill, which a sparrow would not have.  Photo by Joe Sebastiani.

Red-winged Blackbirds are year round residents in this area. In the winter, Red-winged Blackbirds may also be seen flying as part of huge mixed flocks of over a million birds.  These enormous flocks also contain Common Grackles, Brown-headed Cowbirds, and European Starlings.  The flocks roost together at night in marshes and then head out to forage for food during the day.  The Delaware Bay region is known as a huge staging area for blackbirds in the fall and spring.  In fact, most of the entire northeastern North American population of these species stop in the Bay area…over 500 million birds.  (Birds of Delaware, Blackbird Roosts in Delaware.  J.T. Linehan.  pp. 523-4).  Watching these enormous flocks flying overhead is a sight to behold, and really one of the greatest natural spectacles in Delaware.  Listen as they go overhead, and hear the loud “whoosh” as the huge flocks drift past like smoke.  Just don’t open your mouth when you look up!

Some people think of these blackbirds as “ugly” or “dirty”.  Take another look at the individuals.  Grackles and Starlings have beautiful glossy plumage with an iridescence that changes with the light.  Who can deny the brilliant splash of red and yellow on a Red-winged Blackbird’s shoulder?  Appreciate them as adaptable beneficiaries of landscapes altered by human beings; allow yourself to be wowed by their impressive flights; take a finer look at a nearby individual and open your eyes to their subtle beauty.

In winter, Red-winged Blackbirds may fly 40 miles from their night-roosts in Delaware Bay marshes in search of food.  They seek out agricultural areas where they try to gorge on spent corn, as well as a wide range of weed seeds and any insects they can get on the ground.

Red-winged blackbirds are at home in the treeless environment of the marshes at the Dupont Environmental Education Center (DEEC) and perch during the daytime in grasses and cattails.  When spring comes they will nest low among the new shoots of these same marsh plants. Come out to DEEC and see if you can find a few, or a few thousand!

By Jim White: Senior Fellow for Land and Biodiversity

The Christina River has been one of my favorite Delaware canoeing and kayaking destinations for many years. Cruising with the tide on a late summer day is about as relaxing as it can get.  However, if you are like me, the best part of the experience is searching for wildlife such as American Beaver, Great Blue Herons or basking Northern Red-bellied Cooters and soaring Ospreys.  In the last several years, thanks to my friend Hal White (no relation) I have become very interested in dragonflies and the Christina River is a great place to see several of our common species. Scanning the spatterdock and cattails and other shoreline vegetation can result in observing colorful species such as Green Darner, Twelve-spotted Skimmer, Spangled Skimmer and Blue Dasher. However, my favorite species that makes the Christina its home is the Russet-tipped Clubtail.

A Russet-tipped Clubtail photographed by Jim White on the Christina River.

A Russet-tipped Clubtail photographed by Jim White on the Christina River.

This large species of dragonfly is only found on tidal freshwater rivers and is not particularity common elsewhere in Delaware. Hal White, in his book Natural History of Delmarva Dragonflies and Damselflies, wrote that this species was not recorded in Delaware until 2003 when a University of Delaware student collected it on the Christina River for his required insect collection. Why the species was not recorded earlier is a bit of a mystery but Hal speculates that large tidal rivers are not a place that most skilled dragonfly enthusiasts think of checking for uncommon species.  Since the 2003 lucky find, Hal has confirmed that the Russet-tipped Clubtail is actually fairly common on the river from August through mid-October.  However, although I had been up and down the Christina River many times over the years, I had never noticed this what I now consider, a rather conspicuous insect. That is, until 2008 when Hal and I mounted a mini-expedition by canoe to photograph this handsome dragonfly for his upcoming book.   It did not take long after putting-in, that we observed several Russet-tipped Clubtails patrolling low over the water.  But photographing flying dragonflies from a shaky canoe is a bit of a challenge to say the least.  Lucky for me though, one of them perched on an overhanging branch just long enough for me to get a few photos – mission accomplished.  So if you have a chance to get out along the Christina River keep your eyes peeled for Russet-tipped Clubtails.

A Russet-tipped Clubtail in flight, photographed by University of Delaware Professor, Dr. Michael Moore.

A Russet-tipped Clubtail in flight, photographed by University of Delaware Professor, Dr. Michael Moore.

Check out the next canoe trips on the Christina from the DuPont Environmental Education Center and see what you can find: Saturday, September 26 and Saturday, October 17

Natural History of Delmarva Dragonflies and Damselflies  by Hal White available at the Ashland Nature Center, DuPont Environmental Education Center, or on Amazon.com.

By Hank Davis, Delaware Nature Society Board Member and Joe Sebastiani, Seasonal Program Team Leader

In Delaware, after the summer-time Ruby-throated Hummingbird has high-tailed it to the tropics, other species of hummingbirds move in…from western North America!  This fall and winter has been a banner year for western hummingbird species in our area.  Once thought to be an anomaly of migration, more and more western hummingbirds seem to show up in the mid-Atlantic every year in late fall and early winter.  In order to study this migration phenomenon, licensed bird banders attempt to band as many of them as they can.  Through banding, it has been found that some individual western hummingbirds travel east to the mid-Atlantic, then head south to the Gulf Coast, then back to their western breeding grounds in the spring.  Some repeat this cycle for years.

This year, the number of late-season, western hummingbirds in our area has been amazing. In nearby Pennsylvania and Delaware, dozens of Anna’s, Calliope, Rufous, and Allen’s Hummingbirds have made appearances at backyard sugar water feeders since November.  The most common of these has been the Rufous.  Check out the map of Rufous Hummingbird sightings in our area courtesy of www.ebird.org.