Birds

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?

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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!

By Ian Stewart, Ornithologist

Orioles are a type of blackbird that are famous for having both beautiful plumage and a lovely musical song and we are fortunate indeed to have two of them breeding around our area.

Baltimore Orioles build distinctive hanging basket nests along the edges of forests and usually remain quite high in the trees where they feed on berries, nectar and insects, especially tent caterpillars. However, while bird-banding in May we were pleasantly surprised to find a male in one of our mist-nets!

Male Baltimore Oriole

Male Baltimore Oriole

The male Baltimore Oriole is a stunning bird with a jet black head and wings that seem to enhance the brightness of its orange body and shoulders. It was so named because these colors were similar to the coat of arms of Lord Baltimore, the first Governor of Maryland. When seen up close the breast feathers are particularly deeply colored.

Deep orange breast of the male Baltimore Oriole

Deep orange breast of the male Baltimore Oriole

The Orchard Oriole is quite a lot smaller than the Baltimore (only 20 grams vs 35 grams) and is more common in open areas with low trees and bushes where it feeds on insects and an increasing amount of fruit later in the summer. We caught and banded several of them recently in the meadow at Bucktoe Creek Preserve where they were probably feeding on blackberries. Older male Orchard Orioles have a black head and wings but their body and shoulders are a rich chestnut.

Male Orchard Oriole

Male Orchard Oriole

Interestingly, first-year male Orchard Orioles closely resemble the greenish-yellow females but have a distinctive black patch on their throat.

1st Year Male Orchard Oriole

1st year Male Orchard Oriole (if you look carefully you can see a few chestnut feathers on the breast)

Another curious oriole feature is easiest to see up close – they both have a peculiar grayish-blue base to their lower beak.

Blue lower beak of male Orchard Oriole

Blue lower beak of male Orchard Oriole

Both orioles spend the winter in the tropics and Orchard Orioles are already leaving, with most being gone by mid-August, at which point Baltimore Orioles also start to slink quietly away. Try to get outside and see these flaming songsters before it’s too late!

Visit the Bird Banding Stations at Ashland Nature Center (Monday 8am-11am) and Bucktoe Creek Preserve (Wednesday 8am-11am) to join Ian Stewart as he bands, measures, and documents the birds at these locations.