Turkey Vultures are a daily sight as they soar, dip and bank across the Museum’s airspace.

Note the small head, gray flight feathers, and rather long tail on this Turkey Vulture sailing over the Museum.

The slightly smaller Black Vulture, while seen at least once a week here at the Museum, is not as frequently encountered as the Turkey Vulture.

A short tail, small head, and white or gray primaries (the feathers at the tip of the wings) are trademarks of the Black Vulture. Black Vultures flap their wings more often, and more rapidly, than do their larger relatives, Turkey Vultures.

Hardly a day passes without seeing or hearing a Red-shouldered Hawk at the Museum. They are most often encountered while they’re perched in the woods silently watching below for prey.

A Red-shouldered Hawk sits quietly in the swamp between Catch the Wind and Explore the Wild.

Red-tailed Hawks are seen above at least once a week in winter, but there is a two month period during summer when they may not be seen at all. Whenever they do show up, a Red-shouldered Hawk is often there to greet and escort them out of the airspace.

Although larger and more powerful than Red-shouldered Hawks, Red-tailed Hawks are often chased out of the Museum's airspace by the smaller hawk.

This Cooper's Hawk was seen January 28th hunting over Catch the Wind.

Copper’s Hawks have successfully nested here at the Museum for the past two years. I see one of these brazen, bushwhacking, aerial hunters nearly every week of the year, certainly every month. Last week was a double; I saw one (most likely the same hawk) on two different days. Each time, the hawk was hunting from above, settling down into the pines north of the Lemur House.

On February 3rd, a tap-tap-tap-taping sound high in a Loblolly Pine in Catch the Wind signaled the workings of a Brown-headed Nuthatch excavating a nest hole. A pair of these tiny pine dwelling nuthatches had dug two holes in a pine not fifty feet from this location last year, only to give it up (or lose it) to a pair of Carolina Chickadees several weeks later.

One nuthatch quickly exits the hole as the other waits to inspect his handywork.

This pair seems to be a bit ahead of themselves. Last year’s nuthatches were first spotted on February 20 as they had just begun excavation. From the apparent depth of the current hole it appears as though they’ve been working on this one for several days, if not more.

I’ll keep you posted on their progress.

Ravens are large birds, much larger than crows. I would compare their size to that of a Red-tailed Hawk, although their wings are not as broad as the hawk’s wings. Their call is distinctive, especially the croaking call. Listed as Very Rare in our area (Triangle), they are being reported with increasing regularity. I’ve seen a raven on more than one occasion at Occoneechee Mountian Natural Area in Hillsborough, NC but not here in Durham.

Upon the realization that there was a raven nearby, I halted my futile attempt at photographing Butter-butts (Yellow-rumped Warblers) and went off to investigate. The call had come from the area between Catch the Wind and Explore the Wild, above the Lemur House. As I walked up the trail I saw, through the pines, a large black bird fly off in a southerly direction. The bird had the unmistakable wedge-shaped tail of a raven. I quickened my pace, I wanted a photo.

As I came up through Catch the Wind I saw the raven harassing a Turkey Vulture beyond the trees near the Traveling Seeds Exhibit. The bird was moving farther away from me. I moved faster.

A minute (hours) passed before I again saw the raven, this time the bird was quickly moving towards the southwest and was some distance from where I stood. I managed to squeeze off two shots before it disappeared over the pines. Unfortunately, neither image is Pulitzer material, but they’ll have to do.

Common Raven flying over Museum.

From the direction that the bird was heading it must have flown right over the main building of the Museum.

The following day I was alerted by a radio call from Joe Nucilli of the Facilities Department that there was a group of vultures hanging out near the swamp between Catch the Wind and Explore the Wild. I was on my way.

As I walked upon the scene, there were Turkey Vultures circling above and a small group of Black Vultures in the trees; there was something dead in the swamp.

Four of the seven Black Vultures in the swamp between Catch the Wind and Explore the Wild.

Looking closer, I noticed one of the vultures next to a drain pipe which is close to the base of the dike that supports the trail. The bird was feeding on a carcass, a Raccoon.

A Black Vulture feeding on a Raccoon carcass (the animal's ribs are visible just in front of the bird's feet).

Turkey Vultures often find a carcass, but it’s the Black Vultures that usually finish off the animal. Turkey Vultures have a highly development olfactory nerve (they can smell well) and it’s usually the smell that draws them in to a dead animal; the Black Vultures follow them in.

Vultures usually hang out in groups in search of carrion and perch together in trees at a kill site or at their night-time roosts. One of the hazards inherent in these large birds traveling and roosting in groups can be seen in the image below.

Communal roosting has its hazards especially when you perch below a large bird like a vulture. The "whitewash" on this bird's feathers is excrement from a bird perched above it.

This was the same location that I had heard the raven calling from the day before. The raven that I saw had been harassing a Turkey Vulture. Was it a coincidence that I had seen the raven at this spot the day before, and that it had been chasing a vulture. Ravens eat carrion, are well know for scavenging whatever food they can find, and are often accused of being “mischievous.” I think it reasonable to suggest that the raven had been attracted to the activity around the raccoon, stopped in to investigate (or for a bite) and chased off a vulture or two when it left, just for spite. But I could be wrong.

]]> http://blogs.ncmls.org/greg-dodge/2009/12/18/the-raven-and-the-vultures/feed/ 0 http://blogs.ncmls.org/greg-dodge/2008/10/31/282/ http://blogs.ncmls.org/greg-dodge/2008/10/31/282/#comments Fri, 31 Oct 2008 15:02:21 +0000 Greg Dodge http://blogs.ncmls.org/?p=282 Mallards are back in the Wetlands. Three Mutt Ducks (Mallard x Domestic) and eight or so “normal” Mallards have been feeding and resting in the quiet water and under the Willow Trees. Canada Geese are paying regular visits to the Wetlands.

For nearly a week after the passage of the cold front that moved through on the 18th/19th of October the skies were mostly clear with high cirrus clouds making it easy to pick out high flying birds. The 18th and 19th were busy bird days with lots of familiar avian visitors returning from the north. Warblers and other passerines rode in on the back of the front. The rest of the week was busy as well, mainly with high altitude hawks, but with a few other bird types as well. A flock of 13 Double-crested Cormorants in classic echelon formation flapped their way south on the 23rd of the month.

Turkey Vultures and Black Vultures sail over Explore the Wild and Catch the Wind daily, but on the 23rd they were truly soaring high. A group of 8 Turkey Vultures glided by at “little black speck” altitude with a few Black Vultures mixed in. Turkey Vultures (TVs) and Black Vultures (BVs) are fairly easy to separate (images at left). TVs have relatively long tails and soar with their wings held above the horizontal (dihedral). Additionally, TVs tend to teeter, or rock back and forth while soaring, giving them an unsteady appearance in flight. BVs have very short tails and although they sometimes hold their wings in a dihedral they are not consistent in doing so. They also tend to flap their wings rapidly, then glide, rapid flaps, glide. There are other differences, but at great distances these two characteristics are easy to see.

The 23rd was an interesting day for raptors. A Sharp-shinned Hawk and at least two Cooper’s Hawks (at left) were seen soaring high above. Cooper’s Hawks were seen each day following the front. Red-tailed and Red-shouldered Hawks were both up and soaring high and were fairly easy to pick up visually with the lofty cirrus clouds as a backdrop.

For the past few weeks, at least six of our local Blue Jays have been busily flying back and forth over Catch the Wind. They’ve been observed daily flying to large Willow Oaks well behind the Ornithopter, each with an acorn in its bill on the return trip, and probably several more stuffed in its throat. They’re burying, or caching, the nuts. Willow Oak acorns are small and, although I don’t know for sure how many acorns these Blue Jays can stuff into their gullets (perhaps 5 maximum), they’re likely carrying more than one at a time. I once watched a Blue Jay cram 16 sunflower seeds into its throat and one in its bill before flying off to cache the seeds.

I haven’t determined where they’re going with all of those acorns, where they’re burying them, but the cache must be quite large considering the amount of trips observed. Blue Jays will fly several miles to cache nuts. Many of the nuts cached by birds (and squirrels) are never relocated, leaving them to germinate and grow into trees. In effect, the birds (and squirrels) are planting trees. In a paper I read many years ago, one researcher theorized that Blue Jays played a significant role in the reforestation of eastern North America following the most recent period of glaciation. Some have suggested that squirrels were the real heroes of the reforestation story, but squirrels don’t carry acorns far from the mother tree before burying them, perhaps fifty yards if at all. While it’s true that acorns don’t fall far from the tree, Blue Jays will take them there (far from the tree, that is).

Picture the landscape 15,000 years ago when much of North America was under a thick sheet of ice at least as far south as Long Island, NY (Long Island is a terminal moraine). At that time the great eastern deciduous forest was much further south, hundreds of miles south of where it is today. Moving north from this ancient deciduous forest you would probably encounter boreal forest with spruces and other conifers (remnants of which can be seen today on the highest mountain peaks of western North Carolina), scrublands, perhaps steppe or vast dry grasslands, tundra and finally the glaciers themselves, a much different landscape then we see today. As the climate warmed and the glaciers slowly retreated northward at the end of the glacial period, those habitats or biotic zones moved north with them. But how did they move north, and so fast (10-12 thousand years is not a long time)? The trees couldn’t simply uproot and walk north.

As noted, most seeds or nuts that fall from trees, fall directly under the tree. Even the maples, ashes, and poplars with seeds that are carried by the wind and “helicopter” to earth don’t travel very far from the source tree. Left to their own devices deciduous trees would have taken perhaps hundreds of thousands of years to move north to their present locations. Squirrels would help somewhat by carrying off seeds and burying them at least some distance from where they fell to earth. And, as alluded to, it’s well documented that squirrels (or birds) that cache nuts don’t relocate many of the nuts (more than half, if I remember correctly), those nuts later growing into trees. Even with the squirrel’s help, this reforestation would still be a very slow creep north.

A bird that could carry nuts and seeds perhaps half a mile, 2, 5, or even 10 miles from where they originated, and of course, later forget where they were buried or simply just not have enough time to recover them all, would quicken the process considerably. There are many studies showing that Blue Jays will and do carry vast amounts of acorns and other nuts miles from where they were gathered, to be buried and subsequently forgotten, or in which the nuts buried germinated on their own before being used as food. And, the birds don’t put all of those nuts into one hole, but spread them out over the area so there could be many trees sprouting over a relatively wide area. In one study observers witnessed a group of jays move 133,000 acorns. In another, 150,000 acorns in just under a month’s time. That’s a lot of nuts! How many of those were never dug up and eventually grew into trees?

I saw the first-of-the-season Winter Wren and Golden-crowned Kinglet on the 18th of October. I consistently see Ruby-crowned Kinglets foraging with groups of warblers.

A Hermit Thrush was seen on the 29th and was the first one of the season. This bird, and perhaps a few others, will stake out a claim at the Museum near a good source of berries and stay the winter.

If you like sorting through hundreds of warblers, the 18th and 19th of the month was the day to be at the Wetlands. Magnolia Warbler, Black-throated Blue Warbler, Yellow-rumped (Myrtle) Warblers, and Palm Warbler, were all seen on those two days. Butter-Butts, or Yellow-rumped Warblers, arrived en masse on the 18th, making it difficult to sift through them all to pick out the other warblers in the bunch.

Yellow-rumped Warblers should be around for the duration, or at least until they’ve devoured all of the Wax Myrtle berries at the Museum (see Wax Myrtle, Explore the Wild Journal, September 1-15, 2008). While they do quite a bit of flycatching, these warblers can stay farther north than most of their fellow warblers, which for the most part, are strictly insectivorous and need to follow the season south. Besides feeding on the Wax Myrtle, you may catch a glimpse of a Yellow-rump at the bird feeders slurping suet along with one of the the local Pine Warblers.

Yellow-rumped Warblers are named for the yellow patch of feathers on their rump, just anterior of the tail (image above). Although much less colorful in their drab winter plumage, they also show a patch of yellow on each side of the breast. The yellow on the breast varies in brightness according to the age, sex and current plumage of the individual bird but there is usually al least some yellow present.

A few sparrows also showed up during the past few weeks. Chipping Sparrows arrived with the warblers on the 18th of October and a Field Sparrow was seen the following day. Several Song Sparrows were also observed. White-throated Sparrows have returned (see image), and should be with us until early May.

A male Rose-breasted Grosbeak flew in on the 18th and flocks of Red-winged Blackbirds were seen winging by overhead.

There are many young American Goldfinches about. For the past month they’ve been seen at the bird feeders and foraging among the ripening seeds, especially the Tick-seed, alongside the path in Catch the Wind. While the adult Goldfinches have molted into their drab winter plumage making them difficult to separate from the immature birds, the young finches can be differentiated by their buff, or tan-colored, wingbars.