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Monday, June 27, 2011

In Defense

Young Turkey Vultures may be cute, but unless you have had an olfactory operation their sordid stench will keep you, and other potential predators, a safe distance away. Here is another “youngster” that employs a different defense mechanism.
Granted, you might want to think twice about eating something with colorful warts and spiny protrusions, but if you get past the looks, the taste will be repulsive. This Pipevine Swallowtail caterpillar is feasting on Dutchman’s Pipe (Aristolochia).

The plant produces toxic alkaloids that the caterpillar sequesters. These persist in the body and wings of the adult butterfly and even in the eggs. One taste is sufficient to deter predators, namely birds and wasps, from initiating any further attacks. Other swallowtails (such as Spicebush and Black in our area) have similarly dark plumage and gain some order of predator protection from their mimicry of the distasteful Pipevine.

Adult Pipevine Swallowtails are beautiful, large butterflies with flashy, iridescent, metallic blue on the hindwings. They rarely sit still for long and even flutter their wings when nectaring.

Females lay eggs in groups. By the end of the season, the gregarious and voracious larvae can do significant damage to a plant. Visit Chanticleer now to find the caterpillars and again in a few weeks to see the gorgeous butterflies.

Sunday, June 26, 2011

Tagging Turkey Vultures

Turkey Vultures nest throughout the Delaware Valley, but birders seldom see or hear of a nest being found. Both vultures nest on the ground often not providing so much as a scrape for their eggs. They are attracted to cave-like settings which could be a small opening in a rock wall (see Al’s 6/26 blog) or a tumble of boulders, an unused building with two openings, or vegetation that is so dense, it acts like a cave. Such a vegetative structure, a “green cave.” occurred at our banding site at Rushton Farm in Newtown Sq., just north of Okehocking Preserve on Delchester Road.

Bracken Brown with Turkey Vulture chick at Rushton Farm Banding Station
All photos by Adrian Binns
Several Turkey Vultures were in the trees as we were tending mist nets each morning in April. We assumed they were attracted to carrion in the woods. After many days during which even a deer would have been devoured, one bird occupied a snag for many hours and when we passed mist net #6 another vulture often flew out from the shrubbery. My banding partner Lisa investigated the area and found two large eggs with camouflage markings. We immediately changed our route to and from net #6 to protect the nest. We also wanted to avoid leaving our scent which might lure predators. Ha! The strongest human spoor is no competition for the droppings and regurgitated carrion surrounding a vulture nest. Lisa’s German Short-haired pointer went ‘on point’ in front of the entryway. After a few seconds, he wrinkled his nose and trotted off. No fool that dog! Those chicks would be safe from all but the most desperate predator. They have a menacing hiss and painful bite.
36 day old chick regurgitating as a defensive action
On 5/19 Lisa found two tiny yellowish-white fluffy chicks. I contacted my friend Bracken Brown,one of the top vulture banders in North America, who works under the direction of David Barber at the Acopian Center for Conservation Learning at Hawk Mountain Sanctuary. As part of Hawk Mountain’s large vulture research project they wanted to band our chicks when they were about 5 weeks old.

On 6/23 Bracken and Dave Barber grabbed some burlap sacks and entered the green cave to capture our chicks. Both birds were carefully collected and taken to our banding shelter. Vultures defecate on their legs as a cooling strategy. Therefore, metal bands cannot be used. In their place a large plastic tag is attached to the carpal joint showing a color, light blue for our area of PA, and a three digit number, in this case 301 and 250.
Bracken Brown and David Barber attach a carpal tag to the wing
Note the hole in the tongue which allows breathing while large food items are swallowed.
Doris thought the chick was a all fluff, but it weighed almost 5 pounds!
The chicks were checked, measured, weighed and admired before being returned to their green cave. The parents were not present and presumably didn't know the adventure their kids had while they were ‘home alone’.
Lisa Kiziuk of Willistown Conservation Trust with chick #250

Be on the look out for light blue vulture #250 and #301. Report your sightings to Hawk Mountain to contribute to our knowledge of vultures and their movements.

Saturday, June 25, 2011

So Cute! Vulture nest discovered in Delaware County Park

Two Young Vultures in cave at Smedley Park Delaware County
      On Friday, Sharon and I took our grandson Max and his Mom and Dad to Smedley Park to go panning for Garnets in a hillside creek. As we were walking along, before we found the stream we were noticing the large number of American Toads that were hopping around the leaf litter. It seemed like every 50 feet or so we saw another toad. There were more toads out today then I have ever seen in one area before.
       Once we found the creek, we started climbing the hillside and spotted a small cave. My son Chris took Max over to look at the cave and noticed two white clumps at the entrance way and when Chris approached the entrance the clumps retreated back into the cave. He yelled to me that he saw two large baby raptors and that he thought they were vultures. When I arrived at the entrance and peered in, I confirmed the ID. They immediately started to hiss at us and kept it up the hold time we were watching and photographing them.
        When I got home I emailed Doris and asked if she wanted to band them but she told me that the people from Hawk Mountain might want to place wing tags on them instead. So we are in the process of trying to arrange that.
Out of focus cave entrance to nest.
       By the way, we did find a large collection of Garnets and Max had fun playing in the stream and looking for Crayfish and Salamanders.

Tuesday, June 21, 2011

Return of the "Dumpster Heron"

Yellow-crowned Night-Heron, Chadds Ford, Pennsylvania
Delaware County
June 18, 2011~ Photo by Holly Merker

Since summer of 2008, an adult Yellow-crowned Night-Heron has (presumably) returned to a wetlands in Chadds Ford, just inside the Delaware County line. This fine looking bird has been dubbed "The Dumpster Heron"by some birders, since it is most easily seen by standing behind a dumpster in the parking lot of Hank's Place Restaurant on Route 1 in Chadds Ford. The sometimes secretive night-heron can be hit or miss, and this past Saturday was no exception.
Brian Henderson and I tried for the heron around 4:45pm, and had no luck after vigilant scanning. We decided to take a walk along the boardwalk at the John Chadd's house up the street on Creek Road, hoping to catch a glimpse of the bird from another vantage point in this extensive marsh. No luck for us there, but the walk was pleasant as we noted a variety of other birds, a family of muskrats, and a crayfish searching for food in mud.
Forty minutes or so later, we decided to take one more peek behind the dumpster, and see if the night-heron was there. Sure enough, there it was--out in the open and allowing us appreciative looks.
No telling what the restaurant patrons think, as a people wander behind the dumpster with binoculars and camera in hand! However, local birders are very appreciative of Hank's Place for tolerating our visits, and allowing us the opportunity to see this relatively uncommon and elusive species for our area.

Monday, June 6, 2011

Out On a Limb: Red-shouldered Hawks Branch Out

Since my last blog entry on the Red-shouldered Hawk chicks a week ago, the babies have continued to grow, and have become much more active. At this time, 6 June, 2011, I would guess that these chicks are approximately six weeks of age now, give or take a few days since they presumably hatched on different days.

On June 2, I was able to view all three chicks in the nest from the road with my scope. They were quite large, but yet, at times they could hunker down low enough in the nest that they were not well seen.

On June 3, one check spent some time peering over the nest, and was quite alert and attentive to its surroundings. Much of the time, the hawk chicks were quiet, but they were observed by Catharine, the homeowner, and myself to be stretching their wings quite often, and shuffling around in the nest much more than previously noted.

Red-shouldered Hawk chicks on June 3, 2011....Approximately five weeks of age, and still in the nest
I haven't heard any vocalizations while visiting, but the chicks do yawn quite a bit
June 3, 2011

Over the weekend of June 4 and 5th, Catharine reported the chicks had been seen leaving the nest, creeping out to close by branches and just sitting.

On Monday, June 6, the chicks are getting bolder. Two of the three are on branches still within the large oak tree their nest resides in, but more than 20 feet away from the nest. One sits quite high, and is flying from branch to branch, practicing flight.
Red-shouldered chick spreads its wings and tail and practices short flights from limb to limb...
June 6, 2011

All of the chicks are noticed to be preening quite a bit. They all seem alert to their environment, and the two that are out on limbs seem quite comfortable with their new posts.
The chicks are now the same size as their parents. Their immature plumage seems to be fully in, at least on the two chicks that are out on a limb. June 6, 2011

The third chick must be the youngest. It still sits quite close to the nest, and hops back and forth into the nest. It's level of confidence seems much less than its siblings.
This one also appears to have some downy feathers still peeking through in places. Since the eggs hatch on different days, this chick could be several days behind in maturation.
Presumed youngest chick watches the others apprehensively, keeping close to the nest in security
June 6, 2011

Within the next several days, there will likely be more changes in behavior, and in the distance the young will travel from the nest.
It is exciting to watch them change and grow, and yet sad to know they could soon be tougher to locate around the neighborhood. Catharine and Mark and their kids, who have enjoyed this family of young hawks in their oak tree, will be sad to see them leave. But there is hope the parents will return next year, and that they will reuse the same nest.

Friday, June 3, 2011

Shorebirds Over the Pennsylvania Piedmont

During the last week of May, and the first week of June, we here in SE PA can be treated to a phenomena of the bird world like none other--the early evening flight of thousands of shorebirds that have just taken off from the Delaware Bay shores heading to their breeding grounds in the far reaches of the north. Birds like Red Knot, Sanderling, Ruddy Turnstone, Dunlin, and Whimbrel are among the many that will make the journey to the arctic region to breed, and some will pass over Delaware, Chester, Montgomery, and Bucks Counties while there is still daylight available, and at low enough altitudes that we can see and identify them.

The Bucktoe Creek Preserve, a privately owned 297 acre preserve in Kennett Square, Chester County, has been hosting a shorebird watch which started 25 May and will continue through 5 June. The first few nights did not hold shorebirds over our fields, but on May 28, the "birder host" of the event, Larry Lewis, watched Red Knot and Dunlin grace the skies in a group of approximately 200. Other shorebirds were seen in flight, but due to distance, couldn't be identified. The southerly winds and calendar date continued to give us hope. But, all was quiet until May 31st.

I had a feeling things might be good for shorebirds taking off from the Bay that Tuesday evening when I noticed the forecast in Lewes, DE was posting SE winds. I didn't get to the watch site until 7:28. At that time, Larry Lewis told me and the preserve manager, William, that we had just missed (by less than five minutes), a group of Red Knot. Disappointing to hear we had missed them, but optimistic more were to come, I settled in. Within two minutes Larry was yelling "Here they come!" I looked up and saw without binoculars a big flock of birds heading straight towards us. I got the camera ready to go, and was lucky enough to capture some decent record shots of this first flock of birds as they were nearly overhead. This group came in so close that when they banked and turned, we could hear the wind against their wings, and some of the birds calling.

First flock of shorebirds I saw on May 31, 2011. This photo shows a small section of a flock of a few hundred birds. In this capture of the camera, you can see Ruddy Turnstones with their dark facial patterns and light bodies, and the warm ruddy hie, fat bodies, longer wings and bills on the Red Knots.

After this flock, we had a steady stream of various groups allowing for photos and viewing in the scopes. The most popular migrant this night appeared to be the Ruddy Turnstones.
View of the 7:30 flock of shorebirds as they headed away

Some of the flocks were just too distant to identify to species, and were just silhouettes against the evening sky....
A second group of shorebirds came in at 7:41 (above)

This group came in at 7:47pm (above)

7:47 flock over the trees...
This flock had many birds in it, this being
a small section captured by the camera

Some of the flocks were arranged in some unusual shapes
This flock above was shaped like a ladle for a short while!

Another unusual shaped flock

Small clip of the eight o'clock mixed flock

As sunlight diminished, we continued to see the flocks of shorebirds, but seeing much detail became near impossible. Our last flock flew over around 8:35 pm. At this point, it was becoming difficult to see much. We felt pretty sure the streams would keep coming through the night, but would go unnoticed in the dark.
We felt lucky to have witnessed an amazing flight of shorebirds over Pennsylvania, and were happy to have wished them well on their long journey north.

8:35pm flock pushes northward

More information on the Bucktoe Creek Preserve can be found at
The shorebird watch runs from 3pm til dusk until Sunday, June 5th.