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.

By Derek Stoner, Seasonal Program Team Leader

A Red-eyed Tree Frog dazzles with colors when illuminated by a flashlight, as it hunts at night for insect prey in the Costa Rican rainforest. Photo by trip participant Joe Flowers.

A Red-eyed Tree Frog dazzles with colors when illuminated by a flashlight, as it hunts at night for insect prey in the Costa Rican rainforest. Photo by trip participant Joe Flowers.

Continuing our “flashback tour” from our Costa Rica 2015 adventure:

As our group settled in at the comfortable Evergreen Lodge on the banks of the picturesque Tortuguero River, we could hardly imagine the bounty of wildlife could be any greater than what we found right around our accommodations.    Dazzling hummingbirds fed from fire-red Heleconia flowers all around us while White-faced Capuchin monkeys scrambled about in the treetops in search of ripe fruit.   Rainbow-hued land crabs scuttled underfoot to hide in their burrows as they avoided the feet of distracted nature enthusiasts.

A White-faced Capuchin monkey prepares to leap from the tree towards the onlookers. Photo by Derek Stoner.

A White-faced Capuchin monkey prepares to leap from the tree towards the onlookers. Photo by Derek Stoner.

Our evening adventure took us into the dark and narrow canals cut into the nearby rainforest, allowing special access to a world of trees, vines, flowers, and teeming wildlife.  The captain of the boat deftly brought our vessel with close range of the animals while our guide provided a running commentary on the interesting life history of these unique species.

A male Northern Jacana displays for the female while dancing across a bed of Water Hyacinths. Photo by Derek Stoner.

A male Northern Jacana displays for the female while dancing across a bed of Water Hyacinths. Photo by Derek Stoner.

We encountered a very confiding pair of Northern Jacanas, rail-like birds with impossibly long toes that help them walk delicately atop the floating aquatic vegetation.  At point-blank range we witnessed the male showing off his bright-yellow wing spurs while pumping his chestnut-colored wings and chest.  The display continued as we motored on to view the next wildlife spectacle around the bend.

The reclusive Black River Turtle, found only in a small region of Costa Rica, basks on a river-side log. Photo by Derek Stoner.

The reclusive Black River Turtle, found only in a small region of Costa Rica, basks on a river-side log. Photo by Derek Stoner.

Our exploration led us to close encounters with the endemic Black River Turtle, a bright red-and-black Red-capped Manakin, Howler Monkeys hooting overhead, and Great Currasows (a turkey-like bird) scrambling through palm fronds.   As the boat gently nudged a log, a Caiman (small crocodilian) splashed into the water from its camouflaged hiding place.  Our group spied a Boat-billed Heron resting amidst an umbrella of vegetation, staring back at use with its large eyes used for nocturnal hunting.  The rattling calls of Green Kingfishers and Amazon Kingfishers seemed to greet us around almost every turn.

Exploring the river by boat is a fantastic way to encounter wildlife and access unique habitats. Photo by Derek Stoner.

Exploring the river by boat is a fantastic way to encounter wildlife and access unique habitats. Photo by Derek Stoner.


As our blog journey back to last Fall’s Costa Rica trip continues in future posts, we invite you to look ahead on your calendar and consider joining Delaware Nature Society this November for a bigger and better Costa Rica exploration: a twelve-day Tropical Wildlife Adventure.  From the Caribbean to the Pacific, from the lowlands to the cloud forest, we will visit unique habitats and stay at spectacular lodges during this grand tour of the best  natural areas in this tropical paradise.  Guided by Costa Rican native Jose Saenz.

Costa Rica: A Tropical Wildlife Adventure, will run from November 10 to November 21.   Delaware Nature Society staff Judy Montgomery and Derek Stoner will be the hosts and provide you with a first-class eco-tourism experience as we travel together to the tropics.  Member pricing is $3,920 (airfare not included) and includes all lodging, meals, ground transportation, and special experiences like snorkeling.  Call 302-239-2334, extension 127 or email judym@delnature.org for trip details.

Registration deadline is July 31.

 

By Ian Stewart, Ornithologist

“I think that I shall never see, a poem lovely as a tree” (Joyce Kilmer, 1913).

Trying to identify trees is a lot of fun and can be done by anyone with both patience and a good field guide because almost all trees belonging to the same species have the same general appearance in terms of their size, bark, and leaf shape and arrangement. Still, sometimes one comes across a specimen that stands out from the others, perhaps because of its unusual appearance or location. These are my four favorite trees found on DelNature lands.

1) This massive American Sycamore is affectionately known as “Old Mr Knobbles” and is a much-visited centerpiece of the Ashland Nature Center floodplain. Although there are several huge Sycamores growing along the creek they all have a single vertical trunk whereas this specimen has two equally thick trunks, one of which seems to defy gravity by growing almost horizontally!

American Sycamore, Ashland Nature Center

“Old Mr Knobbles” American Sycamore, Ashland Nature Center

2) This Gray Birch stands alone in the corner of the hilltop behind Coverdale Farm. There was a pair of Gray Birches standing side by side here for many years but one was blown down by a storm in the spring of 2016, leaving this distinctively-colored tree standing forlornly against a dramatic backdrop of sweeping fields.

Gray Birch, Coverdale Farm Preserve

Gray Birch, Coverdale Farm Preserve

3) The great majority of trees have just one trunk but this monster Bitternut Hickory hidden away in the woods of Coverdale Farm Preserve has no fewer than six! Although one of the trunks is fairly small and another two are joined at the base it is still an unusual tree as the six trunks form a neat crown that supports the many branches.

Bitternut Hickory with Six Trunks, Coverdale Farm Preserve

Bitternut Hickory with Six Trunks, Coverdale Farm Preserve

4) Swamp Oak. This striking pale gray tree is tucked away in a dark corner of Burrows Run Preserve. As with White Oaks the trunk is relatively smooth near the base but begins to peel and flake further up the tree. However the peeling is so pronounced on Swamp Oaks that the bark seems to hang in sheets like plates of armor!

Swamp Oak, Burrows Run Preserve

Swamp Oak, Burrows Run Preserve

The Plate-Like Bark of a Swamp Oak, Burrows Run Preserve

The Plate-Like Bark of a Swamp Oak, Burrows Run Preserve

There are many beautiful trees scattered around our properties. Next time you walk our trails be sure to look carefully into the woods – you may find your own favorite tree!