Bird Banding

All posts tagged Bird Banding

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

Bird banding is in full swing at both Ashland Nature Center and Bucktoe Creek Preserve and our mist-nets are becoming dominated by Gray Catbirds! Gray Catbirds (Dumetella carolinensis) are grouped with Northern Mockingbirds and Brown Thrashers as ‘mimic-thrushes’ as all three are slender thrush-like birds with long tails and loud, elaborate songs. Indeed, catbirds get their name because of the peculiar cat-like ‘miaow’ call they often give while hidden low in a bush! Catbirds are by far the most common of the three mimic-thrushes however, and can be so abundant that many birdwatchers don’t give them a second glance. This is a pity, because catbirds have several interesting features which are particularly obvious when you are holding them during the banding process.

The first of these is the conspicuous rictal bristles around the base of their bill. Several other groups of birds have rictal bristles (especially flycatchers) and although their exact purpose is unknown they are thought to either have a sensory function or to prevent captured insects from scratching a bird’s eyes while they are being held in their bill.

Four rictal bristles can be seen at the base of this Gray Catbird's bill.

Four rictal bristles can be seen at the base of this Gray Catbird’s bill.

The second distinctive Catbird character is their crimson ‘crissum’. This is the patch of feathers underneath their tail which isn’t always easy to see in the field as Catbirds tend to stay fairly low to the ground. The third interesting plumage character of Catbirds, which can also be seen in the picture below, are the fairly obvious growth bars in their outer tail feathers. Growth bars appear as alternating light and dark bands and each pair of bands represents one 24 hour period of feather growth.

Underside of a Gray Catbird showing the crimson crissum and growth bars in the outer tail feathers.

Underside of a Gray Catbird showing the crimson crissum and growth bars in the outer tail feathers.

Not surprisingly, Catbirds were by far the most frequently caught species during the pilot banding project we conducted last summer at Ashland and Bucktoe. In just 3 months we caught 152 catbirds, of which 87 were juveniles likely hatched locally. So far this year we have recaptured 3 of the catbirds we banded last year and hope to recapture even more as the season progresses. It’s truly amazing to think that these 3 birds spent their winter over a thousand miles away in the south-eastern US or the Caribbean and yet came back to the same few hundred acre spots in DE and PA the following year!

The number on this metal leg band showed that this Gray Catbird was banded the previous year.

The number on this metal leg band showed that this Gray Catbird was banded the previous year.

So be sure to take a longer look at a Gray Catbird next time you see one. They are more interesting than you might think!

Public bird banding sessions are held at Ashland Nature Center on Monday and Bucktoe Creek on Wednesday, both from 8am – 11am, though banding does not take place if it is raining or windy, out of concerns for the birds’ safety.

Note that there will be no banding this Monday (May 30th) due to the Memorial Day Holiday.

By Ian Stewart, Bird Bander

Sparrows are an identification challenge for just about all birders, including myself, as most of them are small, streaky and fairly dull in color (hence their nickname of ‘LBJs’, which stands for ‘Little Brown Jobs’). Telling them apart is made even harder by their skulking behavior, especially outside of the breeding season, with many of them only popping up to give you a brief glimpse before they duck back down into a pile of brush or long grass.

If you do spot a mystery sparrow a quick way to reduce the number of species it can be is to look at its breast. As lovers of the ‘Golden’ field guide to birds will know, you can quickly divide sparrows into those with a streaked breast and those with a plain breast. In my opinion, however, the best thing you can do is to try and get a good look at the bird’s head. We caught several species of sparrow during our bird banding pilot project at Ashland Nature Center and Bucktoe Creek Preserve and this provided a great opportunity to see the head differences at close range.

The ubiquitous Song Sparrow is common year-round in this area and is recognized by its heavily streaked head with rich chestnut patches, as well as a faint eye ring. The Savannah Sparrow is usually only found in this area during the winter or on migration and can be told by its brightly streaked paler face, usually with a yellow patch in front of the eye, and a pale eye ring. The swamp sparrow is a darker bird overall with a much more subdued head pattern, and has a broad greenish-cream streak above a gray face. Note that both the Savannah and Swamp sparrows have a proportionately longer, thinner beak than the song sparrow and presumably eat different types of seeds. The field sparrow is found here year-round and is told by its short orangey-pink bill and plain gray face with a dull brown cap. The individual seen here was a juvenile bird which still has a fleshy ‘gape’ at the corner of the beak and only a hint of the eye ring it will possess as an adult.

Get to know the common, year-round Song Sparrow first with its brown and gray colored head and triangular "Elvis" mutton-chop sideburns.

Get to know the common, year-round Song Sparrow first with its brown and gray colored head and triangular “Elvis” mutton-chop sideburns.

Swamp Sparrows are found in Delaware in small numbers outside of the summer, and in the coastal zone year-round, where they breed.  They are confusing, but look like a Song Sparrow head without the mutton chop sideburns.  They also have a clear breast.

Swamp Sparrows are found in Delaware in small numbers outside of the summer, and in the coastal zone year-round, where they breed. They are confusing, but look like a Song Sparrow head without the mutton chop sideburns. They also have a clear breast.

White-throated Sparrows are very common backyard birds in the non-breeding season in Delaware with a very recognizable and beautiful facial pattern.

White-throated Sparrows are very common backyard birds in the non-breeding season in Delaware with a very recognizable and beautiful facial pattern.

White-crowned Sparrows are not common, but sometimes come to bird feeders.  They are found here at the same times of year as White-throated Sparrows, their relative.  This juvenile sports brownish stripes on a gray head.

White-crowned Sparrows are not common, but sometimes come to bird feeders. They are found here at the same times of year as White-throated Sparrows, their relative. This juvenile sports brownish stripes on a gray head.

Field Sparrows are fairly common year-round residents in Delaware.  The cute looking face with a blank gray cheek, and pink bill are a clue to its identity.

Field Sparrows are fairly common year-round residents in Delaware. The cute looking face with a blank gray cheek, and pink bill are a clue to its identity.

The Dark-eyed Junco is a sparrow too!  They are very distinctive and the males have a gray hood.  Females have a brown hood.  All of them have a white bill.  They are very common backyard birds, especially in late fall through early spring.

The Dark-eyed Junco is a sparrow too! They are very distinctive and the males have a gray hood. Females have a brown hood. All of them have a white bill. They are very common backyard birds, especially in late fall through early spring.

This is the time for Christmas Bird Counts.  You are welcome to watch birds at your feeder and report them to the official following counts:

Wilmington, December 19

Bombay Hook, December 20

Middletown, December 27

Milford, December 30

Rehoboth, January 2

Cape Henlopen/Prime Hook, January 3

Seaford, January 4

If you want to know if you live in any of these Christmas Counts, and would like to contribute your sightings from your yard, or would like to participate with a group, contact the Count Compiler, Jim White at jim@delawarenaturesociety.org.

 

By Ian Stewart, Ornithologist

Some of the coolest birds we have been catching at the banding stations at Ashland Nature Center and Bucktoe Creek Preserve are the ‘tree-dwellers’: the woodpeckers and nuthatches. These birds aren’t always easy to see during the summertime as they spend most of their day deep in the forest, hugging trunks or branches. However, once you learn to recognize the high-pitched ‘peenk’ of the Downy Woodpecker and the nasal ‘honk-honk-honk’ of the White-breasted Nuthatch you soon realize that both of these birds are quite common year-round.

We have caught and banded 11 Downy Woodpeckers since June and they are a treat to handle. Their bill is thin but strong and they have distinctive tufts of stiff bristles over their nostrils which probably stop chips of wood flying up their nose when they are hammering on trees!

Like several woodpeckers, you can tell what sex adult Downies are by checking out how many red feathers they have on their head – males have a red square at the back of their head but females do not. In most birds you cannot tell what sex juvenile birds are but in Downy Woodpeckers you can – the males have a spotted red cap but the females have a spotted white cap. Try to see if you can spot this next time you are out birdwatching!

Woodpecker collage

In this collage, the Downy Woodpecker in the main image is an adult male. In the lower left corner is a juvenile male, low center is an adult female, and the lower right is a juvenile female.

One morning at Ashland a group of lucky visitors were present when a Downy Woodpecker was captured in the same net as a Hairy Woodpecker! The Hairy Woodpecker is a larger version of the Downy but is much less commonly seen or heard, and the two can easily be confused as they look very similar. If you happen to be holding them both however, the difference is obvious – the Hairy is a bulky, powerful bird that is over twice the size of the dainty Downy.

A Hairy Woodpecker is above, and a Downy Woodpecker is below. Notice the beak of the Hairy...it is about as long as the head is wide. On the Downy, the beak is shorter than the head is wide.

A Hairy Woodpecker is above, and a Downy Woodpecker is below. Notice the beak of the Hairy…it is about as long as the head is wide. On the Downy, the beak is shorter than the head is wide.

We have caught 7 White-breasted Nuthatches so far and one of the first things you notice about them is their long thin, uptilted bill, which they use to pry up pieces of bark to get at the juicy insects beneath. Nuthatches can also be sexed according to their crown color, with males having a black crown and females having a paler, gray crown.

A male White-breasted Nuthatch. The black crown and uptilted bill is easy to see.

A male White-breasted Nuthatch. The black crown and uptilted bill is easy to see.

Even though nuthatches are striking birds at any distance they are even more stunning up close, with a sublime mix of black, white and blue-gray feathers and a distinctive patch of pale brown feathers underneath their tail. Interestingly, even though nuthatches spend a lot of their time climbing up tree trunks in the same way as woodpeckers, their toes are arranged like those of most birds, with three toes forward and one back (although the back toe has a long claw, as seen in the photo below). Unlike woodpeckers however, nuthatches will also climb down trunks and branches, and maybe they need three forward-pointing toes to brace themselves on these downward trips?

Note the underside of the White-breasted Nuthatch, and the very long claw on the hind toe.

Note the underside of the White-breasted Nuthatch, and the very long claw on the hind toe.

If you want to see either of these amazing birds, please visit one of our banding stations and you may get lucky. Alternatively, both of them can easily be attracted to bird feeders filled with black oil sunflower seed, especially during the wintertime.

Ian Stewart will be conducting a Bird Banding Demonstration on Saturday, October 10 as part of our programming at the Big Sit.  The Big Sit is an international competition to find as many species of birds from one location, a 17-foot-diameter circle, during the day this Saturday.  The Big Sit will be held at the Ashland Nature Center Hawk Watch, and we will also be offering nature walks at 10am and 2pm, a 1pm lecture on the Raptors of Fall Migration, and food to keep you going!