Birds

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.

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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

acorns

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?

mice2

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

Ian Stewart, Ornithologist

Many visitors to Ashland Nature Center have been enjoying our newest attraction – a bird blind! The bird blind overlooks a cluster of bird feeders along Wildflower Brook and is the perfect place to view birds and other wildlife up close.

These excited campers look out from inside the bird blind. The blind was conceived by Joe Sebastiani and built by our ‘Dream Team’. Photo by Joe Sebastiani

These excited campers look out from inside the bird blind. The blind was conceived by Joe Sebastiani and built by our ‘Dream Team’. Photo by Joe Sebastiani

As long as you sit quietly you can watch dozens of birds come to the feeders, bathe in the brook, or just hang out in the trees nearby, and since they are so close you don’t even need binoculars. This makes blinds an excellent way to get children interested in nature since even youngsters can enjoy watching the birds going back and forth. Having said that, just a basic pair of binoculars lets you see a lot more details of the different birds like their beak shapes and feather colors so try borrowing a pair from the visitor center if you don’t have your own. Blinds are also excellent opportunities for photographers as the nearness of the birds means you don’t need an expensive camera with a super-zoom lens – all you need is patience! If you’re lucky you may also see a Red Squirrel visiting from the nearby hemlocks or perhaps a cute little Eastern Chipmunk, both of which are uncommon mammals in the Piedmont. Imagine how memorable it would be this winter to watch a Red Squirrel searching for food in the snow while you’re sheltered inside the blind!

A Purple Finch occupies every port of this popular feeder! Photo by Hank Davis

A Purple Finch occupies every port of this popular feeder!
Photo by Hank Davis

The blind looks out over several types of feeders stocked with different seed mixes and suet cakes which each attract different species of birds. This variety adds a fascinating insight into how different birds feed – some birds like House Finches and Goldfinches perch happily at the feeders and chomp away until they are done while others like Chickadees and Tufted Titmice zoom in and grab one seed before carrying it away to a nearby tree and hammering it open. Woodpeckers and Nuthatches have a remarkable ability to hang upside down on suet cake cages and peck away at the contents while bigger birds like Blue Jays can’t perch very well and prefer to grab whole nuts from table-top feeders.

This Carolina Chickadee feeds on a hanging-dish type feeder. Check out its leg – it’s banded! Photo by Hank Davis

This Carolina Chickadee feeds on a hanging-dish type feeder. Check out its leg – it’s banded!
Photo by Hank Davis

Visiting Ashland’s bird blind will inspire you to buy your own bird feeder or give one to somebody else (they make great Christmas presents for anyone regardless of where they live in the city or countryside). Just hang them from a tree or pole at least a meter from a window (to minimize window strikes) and see which birds you attract. It is probably best to fill them with black oil sunflower seeds since this will attract many birds although some species prefer millet or nyger (thistle). Wild Birds Unlimited in Hockessin is a great local specialty store for bird food and feeders though most supermarkets also sell seed and suet cakes.

This male Downy Woodpecker is hammering away on a suet cake! Photo by Hank Davis

This male Downy Woodpecker is hammering away on a suet cake! Photo by Hank Davis

For me, watching birds at feeders is both entertaining and soothing and a bird blind stocked with several feeders is the sum of human happiness, as well as a relaxing way to connect people of all ages with nature. Next time you have a free hour or so come and hang out at the Ashland bird blind and see what I mean!

By: Ian Stewart, Ornithologist

Delaware birders are out in full force at this very moment and one of their main targets is migrating warblers. Warblers are small, colorful songbirds which flit actively from tree to tree picking off insects with what the field guides usually describe as thin pointed beaks (also known as ‘bills’). But are warbler beaks really all small and pointed? We have handled several warblers during the Delaware Nature Society’s bird banding project and a closer view reveals a surprising amount of variation in the size, shape and color of their beaks.

The Northern Parula is one of the smallest warblers and has a very thin and pointed beak which it uses like fine tweezers to glean tiny arthropods from leaf surfaces.

Northern Parula

Northern Parula

The Prairie Warbler also has quite a sharp beak but it is shorter and more rounded than the Parula’s. Its beak is jet black unlike many of the other warblers which have brownish two-toned beaks with the upper mandible being darker than the lower.

Prairie Warbler

Prairie Warbler

The Mourning Warbler has a fairly substantial bill for a warbler. Mourning Warblers tend to feed on or near the ground and perhaps eat larger insects or grubs.

Mourning Warbler.

Mourning Warbler.

Waterthrushes are relatively dull, streaky warblers that live along streams where they pick arthropods from the surface of the mud and rocks. There are two species, the Louisiana and the Northern, which look very similar but can be partly distinguished by their beak length. The Louisiana was once known as the ‘large-billed waterthrush’ and you can see from these photos that their beak is indeed longer and a little heavier than the Northern.

Louisiana Waterthrush

Louisiana Waterthrush

Northern Waterthrush

Northern Waterthrush

The American Redstart has an unusual beak for a warbler. When seen from above (or more commonly, from below!) its beak is broadly triangular and looks more like that of a flycatcher than a warbler (see the photo below). It’s probably no coincidence that Redstarts often feed by leaping off branches and grabbing insects in mid-air. The conspicuous bristles around the base of their beak may help them trap these insects.

American Redstart (left) and Northern Waterthrush Beaks

Comparison of beak thickness in American Redstart (right) and Northern Waterthrush (left)

Another warbler with an unusual beak is the Yellow-breasted Chat. The Chat is a large, stocky bird that some people do not even consider a warbler, and it has a correspondingly huge, stout beak with a rounded upper mandible. Chats have such a big beak that they can chomp on insects such as grasshoppers that that are too big for the other warblers and can also eat berries.

Male Yellow-breasted Chat

Male Yellow-breasted Chat

Insects and other arthropods are the staple food of all warblers and yet the variation in the size and shape of their beaks suggests that each species eats different prey. This partly explains why some species are usually seen actively hunting in the upper canopy of either deciduous or pine trees while others creep slowly around on the ground, perhaps waiting for an arthropod to emerge. Warblers are passing through Delaware as we speak so next time you see one, take a good look at its beak and see if you can guess what it feeds on!