23 de mayo de 2020

Field ornithology day 5 - good birding spot #2

Today I arrived at the boat launch parking lot near Delta Park around 6:50 am. It was another clear blue day, with the temperature a comfortable 55° F. By the time I left, around 11:30 am, it had gotten up to almost 80°, with more to come - today would prove to be really hot, but thankfully not awfully humid.

Luke was waiting for me when I got to the parking lot, and as we said hi I noticed some movement in the tall trees surrounding the dirt parking lot. I looked up, and found myself face to face with a Bay-breasted Warbler. This was probably the highlight of my day - a bird I had never seen before, and a particularly beautiful one at that. I also heard its song, which was distinctive but which I suspect I'll forget before too long! Too many songs to try to keep straight in my head.

From the parking lot we walking in towards the sand dunes and mud flats. On our way we saw a female Common Merganser, a Ring-billed Gull, and three or four Great Egrets. We arrived at the water's edge only to find that it was so high that the mudflats were basically totally obscured. Not to be stymied, we turned around and headed to the bike path. On our way back we saw a Mallard and a few Canada Geese.

Once on the bike path, we starting really hearing a lot of songs. A Carolina Wren was immediately recognizable, as was a Scarlet Tanager which we were lucky enough to see as well as hear. A Hairy Woodpecker flew in front of us, and we heard and then found a Red-eyed Vireo singing a little lower down than normal. To our left was some flooded forest - Luke noticed movement in the water, and as it turned out a Wood Duck pair was serenely gliding along.

Next we saw a Common Grackle, and heard Tufted Titmice singing. American Robins were hard to distinguish from the Scarlet Tanager, but we did it. As we walked further down the bike path, we started hearing the "weep" of a Great Crested Flycatcher - and there it was in a nearby tree. Yellow Warblers and White-breasted Nuthatches joined in the morning chorus.

After a while we got to the bridge over the Winooski, and found a new suite of birds there, including Double-crested Cormorants, more gulls, a distant and unidentified tern, and many Barn Swallows. We crossed the bridge, heading to Durway, and encountered the first of many American Redstarts as well as a few Warbling Vireos along the bike path. At the entrance to Durway, we were stumped for quite a while by what turned out to be (big surprise) an American Redstart - they continue to infuriate, if only they weren't so cute! We also heard Common Yellowthroats and a Hermit Thrush, and saw a few Veery's flitting around in the underbrush.

We walked the path at Durway past the old rusted out car and the fallen down "end of trail" sign. Just before we arrived at a medium-sized clearing, we saw movement in the canopy and found ourselves looking right at a Blackburnian Warbler. Although I'd heard a few this week, this was the first I'd seen. It was a treat. Walking into the clearing we encountered a birder who we'd met at Geprag's earlier in the week. She was looking at a mystery warbler, which I never got a good glimpse of. As I tried to, though, I did see a Blue-gray Gnatcatcher and a few Chestnut-sided Warblers, so it wasn't entirely unproductive. A Least Flycatcher called from the edge of the woods and then made an appearance, not as glamorous as the Blackburnian but still a nice sight.

From the clearing, we continued along a faint path until we got to a marshy area full of buttonbush. I hoped to see or hear a Willow or Alder Flycatcher here, but maybe the habitat was wrong or maybe it was just too early. At any rate, we did see an American Goldfinch and a Tree Swallow, as well as a whole bunch of Robins and a Brown-headed Cowbird. We walked a little further, then turned around and headed back out of Durway by way of a circuitous route that took us across the path of three lovely deer. On our way out we heard a House Wren, a bunch of American Redstarts (as always), and a mystery bird which Allan says sounded like a Blackpoll Warbler. Perhaps a slightly lost migrant!?

Back on the bike path, we heard and then saw a Baltimore Oriole, then heard a Belted Kingfisher fly overhead making its harsh rattling call. Finally, we arrived back at Delta Park and decided to give it another try. We saw a Spotted Sandpiper and heard a Marsh Wren, which was nice, but possibly not worth the absolute soaking my bottom half got when I tried to cross some apparently solid ground and found myself up to my waist in mud with a deceptive surface coating of reeds. On our return to the parking lot it was really heating up, and things had gotten rather quiet. No more Bay-breasted Warblers singing. That wrapped up our final day. Overall, a nice one and a good end to a wonderful week of birding! Thank you Allan and Jim for facilitating and answering lots of questions. I'll look forward to our field trips in the fall.

Ingresado el 23 de mayo de 2020 por sam_blair sam_blair | 37 observaciones | 0 comentarios | Deja un comentario

21 de mayo de 2020

Field ornithology day 4 - good birding spot #1

Today my partner Kayli and I arrived at Woodside Natural Area around 7:00 am. Stepping out of the car, it was quickly apparent that we were in for another beautiful day. The sky was clear blue, with an occasional light breeze, and the temperature was hovering around 58° F. By the time we left, around 11:00, it was up to 77°.

We met Luke by the parking area and started into the woods. Right away the bird song was almost overwhelming. I picked out a House Wren, a Goldfinch, a Common Yellowthroat, and many American Redstarts right off the bat, but there were more that got past me. As it turns out (after consulting with Alan about a recording of a particularly difficult redstart song) I also heard a Yellow-throated Vireo, although I didn't recognize it in the moment. Robins, Cardinals, and Song Sparrows rounded out the chorus.

We took a left where the trail branches and heads up above the swamp. As we walked over the boardwalk there we heard a Warbling Vireo at the same time as we saw two Blue-gray Gnatcatchers, which led to some confusion until we sorted things out. Then a Red-bellied Woodpecker called, a sound which I mistook for the "reeeep" of the Great Crested Flycatcher. That too, though, was sorted out with time, and I think I can remember that the Red-bellied's call is harsher and less whistled than that of the Great Crested. Around this time we also saw the first of many Veery's, although we didn't hear any singing until the very end of our time birding this area. A few Cedar Waxwings flew around what may have been a blossoming apple (it was certainly a blossoming something).

Up top, we were walking and listening with relatively little to show for it when I saw a flash of yellow and lifted my binoculars. There in front of me was a Magnolia Warbler - the second in two days, although the habitat of today's spotting was about as different from the high elevation spruce-fir forest of yesterday as could be. In fact, I was quite surprised to see this warbler in this spot, but there's no arguing with the clear-as-day evidence of your own eyes! Maybe they are migrating through right now and can be found just about anywhere?

Further along the trail we starting hearing and seeing the abundant Red-winged Blackbirds of the marshy area below, while a Least Flycatcher "che-lek"ed from the woods to our left. A few Gray Catbirds chased each other around, and, I should note, American Redstarts were just everywhere in sight. In fact, they were everywhere within hearing range, too. Those songs continued to confuse me after four hours listening to them. Just highly variable and quite similar to others like the Chestnut-sided.

Speaking of Chestnut-sided Warblers, we saw and heard one right around this time. I was pleased that I called it correctly by song given all of the confusing redstarts that were singing all around it. As we walked through the mature woods on that side of the marsh an Indigo Bunting flew up to the top of a tree, a lovely surprise as always. We stopped at the faithful bench above the marsh, where we started to see and hear Grackles as well as two pigeons (aka Rock Doves) which confused me momentarily because I didn't expect to find them here.

As we continued on, the trail started to lead us down into the marsh (an old oxbow, perhaps?) and across it towards the river. There we glassed the bank and saw a Spotted Sandpiper. Walking along the edge of the marsh, now down at its level, we started to see Yellow Warblers galore. Then a Baltimore Oriole sang and flew to a high, exposed perch. A little further along, two males would fly right in front of our faces, so close they made me start.

Around this time we started hearing the distinctive "teakettle, teakettle" of the Carolina Wren. I haven't seen or heard one of these in a while, so had trouble remembering what bird that classic mnemonic goes with. Luke figured it out with the help of the Google machine. Another fun sighting around this area was a Black-capped Chickadee pulling down from a cattail, likely to be put to use in nest construction. I worked for Audubon VT for the last two summers and did nest box surveys for part of one summer, so I could visualize the nest that little chickadee was building quite clearly.

We stepped in closer to the marsh and paused for a while, and after five or so minutes of normal background song heard (unmistakably, this time) a Great Crested Flycatcher. Then two of them flew near us, showing off their orange and yellow coloring to great effect for Kayli, who had never seen one before. After that we kept walking the path, and ended up near the river again in the little field. There we spotted a Belted Kingfisher out on a perch over the river. Then we walked back up the trail to our cars, pausing to observe a cluster of birders observing what may have been a female Scarlet Tanager (but then again, it could have been a female Yellow Warbler just as easily for all I know).

I thought that would maybe be the end of our birding day, but Luke mentioned that another trail starts a little further up the road and runs to the St. Mike's compost pile. So we headed up there to see what we might see. One thing we saw was a wild John Benner, a Rubenstein student who we had also seen at Geprag's on Tuesday. Actually, that was about all we saw. But we heard a Wood Thrush, an Eastern Wood-Pewee, a few Blackburnian Warblers (way too high to catch a glimpse of, although my neck will testify to the fact that we tried), and some American Crows. Oh - and we caught a glimpse of another Magnolia Warbler, a male, making two for today! They must be well into their migration to be hanging out so far from their familiar habitat. That sums things up pretty nicely. A good day overall, although it wasn't dripping with spring migrants the way I might have hoped. Looking forward to tomorrow!

Ingresado el 21 de mayo de 2020 por sam_blair sam_blair | 34 observaciones | 0 comentarios | Deja un comentario

Field ornithology day 3 - forests

Today I arrived at the Burroughs trailhead around 7:15. Luke was already there, and two other people in our class, Taylor and Grace, arrived shortly after me. They said they could use some help, so we all teamed up and spent the day together. The weather was cool, around 50° F, and it got cooler as we climbed - but on our way back down I would guess it had warmed up to at least 60°. It was a clear, blue day - not a cloud in the sky, with the occasional light breeze. All in all, a beautiful day to be out in the woods.

Things started well in the parking lot, where I heard a Dark-eyed Junco, a Blackburnian Warbler, Black-throated Blues and Greens, and a Scarlet Tanager. But once we headed up into the woods it was surprisingly quiet. Just the Black-throated Blues and Greens (a lot of them), Yellow-rumped Warblers, and Ovenbirds. The relative quiet did have a plus side, though, which was that it made things a little less overwhelming for those of us who were trying to learn the songs of the birds we were hearing. About half a mile up we flushed a few Blue Jays from the trail. A little further along we heard what I assumed was a Red-eyed Vireo, but when we got eyes on it we saw not one but two Blue-headed Vireos! I am always so happy to see these beautiful birds, and it was a good reminder that identifying vireos by song will always be a tricky endeavor.

Further up the trail, Dark-eyed Juncoes flitted from branch to branch. A Black-and-white Warbler also made an appearance. At this point we were starting to climb up out of the pure deciduous forest and into the more mixed-woods type habitat. We heard Red-breasted Nuthatches "yank"ing in the distance, then saw one on a tree. Patches of snow started to appear, as did more Yellow-rumped Warblers (whose songs, I will note, continue to confuse the heck out of me). The snow became more regular, and the forest started to consist mostly of spruce and fir with a few birches mixed in. A Winter Wren sang from the deep woods off the trail.

Then we got into Blackpoll Warbler territory, a bird which I have heard described as "nature's hearing test." It lived up to its name for sure. The snow now covered the ground and radiated cool air up at us (or I guess it would be more correct to say that it cooled the air settling down around us). I didn't get a glimpse of the Blackpoll on our way up, but did see hear and then see a few Golden-crowned Kinglets flitting through the fir branches. Beautiful birds.

At this point I donned my microspikes (I was the only one to bring them along, which left me feeling a little guilty as the others slid around on the icy trail). We had been going for about two hours and things were getting steep. Things were also getting remarkably quiet. Apart from the occasional distant raven, we didn't hear a thing for a good ten or fifteen minutes at a time. After a while like this, we got to the clearing where the Burroughs trail meets the Long Trail. It was around 10:00. Here we stopped, ate a snack, and soaked up the gracious, warming sun. A Turkey Vulture floated by overhead, and a Yellow-rumped Warbler showed off for me from a few feet away. I would have loved to get up to the summit, but we were feeling time-constrained in terms of getting back home for the 1:00 check-in. So we turned around and headed back down, back into the cool shade of the woods.

Things were relatively uneventful, with a few Blackpoll Warblers singing in the distance, until I heard a saw movement and a glimpse of yellow in some thick balsam fir. And with something resembling divine grace, a male Magnolia Warbler flitted right into an opening and sat there showing off for a good thirty seconds. It was the highlight of my day. I was also pleased to learn that I did in fact recognize his song, which is one of the ones I've been studying on my own.

A little further down, the Blackpoll Warblers started to sound particularly close, and I played a song to see if I could call one in. Indeed, in one came with aplomb. I had never seen a Blackpoll Warbler in the field before, so this was a real treat. We continued to slide our way down into the mixed woods, where conditions eased up enough to allow me to doff the microspikes. I heard an interesting sound around now, which I didn't realize until checking with Alan was actually a Brown Creeper. It didn't quite have the full "trees, trees, beautiful trees" sound to it, but listening back to it I can hear the Brown Creeper-ness of it.

That about wraps up the day's bird observations, but I will note that the forest floor down in the deciduous woods was just strewn with Trout Lily, Spring Beauty, and Trillium in bloom. A beautiful sight! we made it back to the cars just on time, and for a final treat a Pileated Woodpecker flew right in front of my car as I drove on Hinesburg Hollow Road back to my home in Shelburne. Overall, things were surprisingly quiet in the woods today, but I still saw some good stuff!

Ingresado el 21 de mayo de 2020 por sam_blair sam_blair | 18 observaciones | 0 comentarios | Deja un comentario

19 de mayo de 2020

Field ornithology day 2 - grasslands and shrublands

Today Luke and I birded from 6:45 to about 11:15, for a total of roughly 4.5 hours. The weather was cool in the early morning, around 48° F, but becoming quite warm, around 60° F by the late morning. The sun was shining, with some high wispy clouds covering about 20% of the sky. The wind was light.

The first sound I heard when I stepped out of my car this morning was the familiar "drink your teeeeee" of an Eastern Towhee. Luke and I quickly spotted him singing from a perch above the parking lot - a good first find of the day. Next we saw and heard a wood thrush and a catbird right near the beginning of the trail. Things didn't waste any time in heating up - we were only a short way up the trail when we heard the "bee-buzzzzzz" of a Blue-winged Warbler from a tree at the edge of a nearby clearing. I had just mentioned to Luke that I was hoping to come across Blue-winged and Golden-winged Warblers and immediately regretted the possibility of having jinxed it altogether, so this song was a welcome one.

We clambered through some raspberry and looked up into the nearby treeline, and there it was! A beautiful Blue-winged Warbler, apparently not a hybrid, singing his heart out. He flew after a while and we walked after him, further up the trail. When we got to the clearing with the benches my second wish was fulfilled, because there was an awfully familiar buzzy song, "zee-zaa-zaa-zaa" to be heard from the top of a dead tree in the middle of the clearing. We got some great looks at this Golden-winged Warbler, who was not shy about showing off his lovely plumage.

So everything I had hoped for had pretty much come to pass in the first twenty minutes - but there was so much more time to spend! We wandered the back trails and came across abundant Common Yellowthroats, Chestnut-sided Warblers, Yellow Warblers, a Veery and a Blue Jay. It was a good opportunity to practice warbler songs, especially once some American Redstarts joined in the chorus. Further out towards the fields we heard the "ticking time bomb" (as Luke described it) sound of the Field Sparrow. We also came across a House Wren, an Eastern Bluebird, and an Eastern Kingbird. Song Sparrows were also present in abundance.

Crossing the fields to the west and walking up into the woods, we started to see and hear a different suite of birds. Ovenbirds sang from the understory and a Pileated Woodpecker called. American Goldfinches danced through the trees and Yellow-bellied Sapsuckers drummed. We climbed the small hill and came out in some fields that I suspect are not part of Geprags Park (oops). I have no regrets, though, because there in some tall trees in the middle of the field were two Indigo Buntings, one of them perhaps an immature male. They weren't singing, but they were proudly showing off their colors for all to see.

A little further to the north, along the edge of some woods, we saw a Yellow-rumped Warbler. We also heard the "che-bek" of a Least Flycatcher and the "wheeeep" of a Great Crested Flycatched. Then we turned around and headed back south along the power line cut. Walking under the powerlines we heard and then saw some Bobolinks flying overhead - a real treat. We made our way back to the park proper, surrounded by Song Sparrows and the occasional Bobolink. Then it was back into the woods, this time on the eastern side of the park. There we heard many more redstarts, a Northern Cardinal, a Rose-breasted Grosbeak, a Hairy Woodpecker, and - excitingly - the first Scarlet Tanager of the year for me (although I suspect I saw one fly at Shelburne Pond a few weeks ago, I can't be 100% sure). That "chick-brrr" always lifts my spirits.

That was it for Geprag's, but since it was still relatively early we decided to head to the other location Jim had given us, Lagoon Road in Hinesburg. It was just a short drive away and it brought us within striking distance of a sandwich place, so it seemed like a win-win. However, when we got there things didn't look too good. I could picture expansive fields there in the not-too-distant past, but as it stands today part of the eastern field is taken up by a solar installation, while the other part is tilled and covered in black plastic. Meanwhile on the western side a tractor was busy tilling up the ground. We did see plenty of Ring-billed Gulls following in the tractor's wake, and Barn and Tree Swallows were perching and flying around. Red-winged Blackbird were everywhere. And a few Canada Geese sat in the field. Apart from that, things were not too exciting. But on our walk back to the car, we did see a Red-tailed Hawk floating in the distance - a consolation prize, as Luke said. That about wraps up our day - I won't go into detail about the delicious sandwich I enjoyed shortly thereafter.

Ingresado el 19 de mayo de 2020 por sam_blair sam_blair | 38 observaciones | 0 comentarios | Deja un comentario

Field ornithology day 1 - water birds

Today I birded from about 6:45 in the morning until around 11:00. Luke Beeson and I paddled my canoe around the perimeter of Shelburne Pond. The weather was cool (and cooler over the water), around 55° F with light wind. There was 100% cloud cover with some occasional very light sprinkles.

Luke and I put in at the boat launch at around 6:45. Right away we saw and heard Gray Catbirds, a House Wren, Red-winged Blackbirds, a Song Sparrow, a Northern Cardinal, an American Robin, and some Yellow Warblers. Classic birds of a suburban-wetland eco-tone, in my mind. Two Mallards swam away from the launch when we put the canoe in the water. In the distance, from the deeper forest to our northwest, a Black-throated Green Warbler sang its characteristic "see-see-see-soo-see." A Caspian Tern flew overhead and dove for fish, prompting a spirited discussion on the Caspian vs. Common tern id debate. Caspian won over in the end for the way its bill was held as if it was weighing down the whole head, the lack of a black tip to the bill, and size.

As we started to paddle, it quickly became apparent that the day would be blessed with an abundance of Common Yellowthroats - they were everywhere, flitting through the foliage near the water's edge. We paddled close along the edge of the lake, startling a pair of Canada Geese who flew away honkingly. Then we startled another pair of birds who prompted considerably more excitement than the geese - two Black-crowned Night-Herons, who flew right over our heads and away across the lake.

Further towards the wetlands on the eastern side of the lake, we became aware of the chipping of Swamp Sparrows and the hurried, hunched over movements of a little Northern Waterthrush right at the water's edge. Good thing Luke was there - I don't quite know what I was thinking, but my first association when I saw it was Song Sparrow! In my defense I didn't get a good look at it at first, but I realize now that its movement (and habitat) is distinctive on its own. Another bird we saw a lot of was the Double-crested Cormorant. We frequently saw them lined up on logs sunning their wings. Eastern Kingbirds also made an appearance, living up to their reputation for feistiness as two fought each another in the air.

Moving up along the coves on the eastern side of the lake, we saw an Eastern Phoebe on a branch above one of the cliff faces, heard Black-and-white Warblers in the woods, and encountered the first of many Spotted Sandpipers, with their distinctive fluttering wingbeats and incessant butt-bobbing. We also saw a Common Grackle. Over the lake, Barn and Bank Swallows coursed low.

Now I have to make a case for our unidentified accipiters as two Northern Goshawks! They were just gray all over, with rectangular tails - and why would two male northern harriers be flying over a lake together?? Goshawks, on the other hand, like to hunt over open spaces like lakes, or so I read in my Sibley. Just saying... They were certainly no Red-tailed Hawks. Wish you had been there to see it, Alan.

The birds of the forest continued to sing and call loud enough for us to hear on the lake as we approached the northern end - Mourning Doves, Common Ravens, Chestnut-sided Warblers, and American Goldfinches all made an appearance (vocally, at least). A Belted Kingfisher flew overhead. And then, at the cattail marsh at the far end of the lake we heard the first of the day's Marsh Wrens singing! I was pleased that I had recalled the song from the last time I heard it, a few years ago.

Moving west now, we heard Black-capped Chickadees and Blue Jays in the scrubby woods. Then we saw a few male American Redstarts flitting through the trees. And then, in what was perhaps the highlight of the day, a little yellow blob high up in an aspen over the water proved to be a Wilson's Warbler - the first I've ever seen, and what a sighting this was! Clear as day. In the background, from a perch high up in a tree, a Brown Thrasher provided accompaniment.

The last leg of our paddle, down the western side of the lake, led us past a beaver dam where the beaver had apparently gone crazy and started chewing every massive cedar in sight - bad forestry, as Luke said (although I'm inclined to think that beavers are always good foresters, just by virtue of their beaveriness). The birds were starting to quite down at this point, but we heard a Hermit Thrush singing and saw a few Veery's at the water's edge. A Turkey Vulture soared overhead. We returned to shore quite content with our sightings, but on the way to pick up a sandwich at the mill one last surprise awaited us - a female Northern Harrier coursing low over a hay field, which nearly led me to drive off the road in excitement. Overall, a beautiful day among the birds of the water and land.

Ingresado el 19 de mayo de 2020 por sam_blair sam_blair | 39 observaciones | 0 comentarios | Deja un comentario

26 de abril de 2019

Field Observation 6: Reproductive Ecology

On my walk in Red Rocks Park in South Burlington, I saw and heard many behaviors related to mate selection and territory selection and defense. In particular, I heard the songs of male Cardinals and American Robins everywhere I went, and the presence of multiple singers in each area I heard them indicates to me that singing, an energetically costly activity, is being undertaken as a way to establish territory and perhaps defend mates. This makes sense for the time of year, since we have just begun to experience the warm spring days that serve as a signal to begin mating for these species. Both Cardinals and Robins are probably nesting in the dense brushy areas immediately adjacent to the entrance trails at Red Rocks (making it easy for me to hear them). At 7:30, I observed a Northern Flicker enter a hole in a beech tree ~ 40 feet above the ground. This tree was located on a rise about 60 feet from the water. The bird very gradually peeked its head and then its body into the hole, and once it fully entered, it did not reemerge. This behavior seems consistent with the Flicker's use of nighttime roost cavities, but the Flicker also builds its nest in cavities. It does not seem unlikely that nest cavity selection is at least partly based on knowledge gained from roost cavity use, so this behavior may have been associated with nest selection. Lastly, I saw at least four Buffleheads on the bay: a male, a first-winter male, and two females. The mature male's head-crest display is striking and conspicuous and serves a role in mate selection, and occasional flapping behaviors exhibited by all the ducks (but perhaps the mature male more often) may have been courtship or dominance displays. They may nest in the vicinity of the bay, someplace quiet where there are dead trees near the water's edge.

Northern Cardinals nest in dense foliage, generally not above head-height, where the female carefully builds a nest cup with four distinct layers. Buffleheads, on the other hand, nest in hollow trees near the edges of ponds and bays. The females do not gather nest material - they simply shed some of their breast feathers and line the nest with these. Some of the nest cavities found and reused by Buffleheads are made by Northern Flickers - the same bird I saw entering a cavity in a beech tree. Flickers build their own nest cavities in dead or diseased trees using their powerful beaks, and leave the cavities bare except for a bed of wood chips.

I heard at least 7 different species during my "sound mapping" exercise. In retrospect I think it was a quiet moment to choose - it was getting cold and dark, and the birds were not singing as much as I might have expected. Interestingly, I noticed "paths" of movement in different parts of the area around me. To the north, American Crows made quiet sounds as they flew overhead from SW to NE. In the area to the west of me, a small flock of Black-capped Chickadees made chips and quiet calls as they moved through a tall stand of white pine. I heard about three Cardinals, two Robins, three American Crows, at least three Chickadees, one of what I think was a Dark-eyed Junco, and one gentle soo-see-see-see song that may have been a sub-song phase White-throated Sparrow.

Ingresado el 26 de abril de 2019 por sam_blair sam_blair | 9 observaciones | 0 comentarios | Deja un comentario

07 de abril de 2019

Field Observation 4: Migration

I went to Shelburne Pond Natural Area on Sunday, 4/7 from 3:30 to 5:00 pm. It was a mild 50°F with little to no wind and 100% cloud cover. There was no precipitation.

I walked a ~2 mile loop around the southwestern part of Shelburne Pond. I saw two male Wood Ducks (and heard a female) in the whitecedar swamp. I heard and saw a flock of Black-Capped Chickadees in this area as well. I heard and saw at least 3 Song Sparrows in brushy edge habitat near the parking lot. I saw a Common Raven fly overhead and heard many ravens on the far side of the pond. There were Canada Geese in the fields near the access road, and also in this area I saw two American Kestrels. Initially they were sitting on telephone poles, but then both individuals flew to a dead tree in the field and subsequently flew intermittently from the tree to different spots in the field. I did not see if they were feeding. I also saw some starling and a Rock Pigeon on a nearby barn.

Black-capped Chickadees and Common Ravens are both year-round residents in VT. They are both quite smart birds. The BCCH displays both physiological and behavioral adaptations to life in winter. These include food caching and the ability to enter a state of facultative hypothermia. The raven is intensely intelligent and able to exploit many food sources as they become available. However, research still shows that a high percentage of juvenile ravens do not survive their first winter. Both birds stay here year-round because they are able to find sufficient food in the winter; generally the evolutionary decision to expend energy on migration has more to do with a lack of food than with low temperature (although availability of food depends on temperature).

The Canada Goose is a facultative migrant. It travels irregularly in response to local conditions. I'm not sure where the geese I saw were coming from, but they could have been as close as southern Vermont or northern Massachusetts. They may be staying in this area for the whole breeding season. They depend on a) open water and b) agricultural or suburban open land to breed and forage, respectively. The Shelburne Pond area currently has open water in parts of its boundaries, and the fields around the pond are thawing out and quite muddy. This likely means that there is sufficient food in the form of seeds and sedges in this area for the geese to stay, and there will be more and more food available as the grasses begin to grow and the lake thaws.

The Song Sparrow is an obligate migrant. It travels as far south as Florida and northern Mexico in the winter, and breeds in Vermont and into Canada. It has arrived in the last week or two, as far as I can tell. This "choice" must be linked to food availability. The beginning of the spring thaw must bring back to "life" sufficient insects and invertebrates for subsistence in the sparrow's preferred habitat, which is brushy edge habitat near open fields or forest edges. It's important to the Song Sparrow to arrive as soon as possible after food becomes available because the spring is when Song Sparrows establish territories and begin to attract mates. An earlier bird will tend to be a more successful bird, as long as it arrives after food has become available. However, if it arrives before food is available, it will either be a very hungry or a dead bird - a definite disadvantage.

The maximum straight line distance likely traveled by the migrant species I observed is ~ 2600 (American Kestrel) + 2300 (Wood Duck) + 1600 (Song Sparrow) + 200 (Canada Goose) miles = 6,700 miles. Wow.

Ingresado el 07 de abril de 2019 por sam_blair sam_blair | 8 observaciones | 0 comentarios | Deja un comentario

23 de marzo de 2019

Field Observation 3: Social Behavior and Phenology

I walked a ~ two mile loop in Centennial Woods on Saturday, 3/23 from 1:30 to 2:45. The weather was fair, with light-moderate winds, 50% cloud cover, and temperatures around 32° F. It was snowing in the mountains, and there was ~3 inches of fresh wet snow on the ground and clinging to tree limbs in the woods.

I heard BCCH making contact calls (high-pitched chips) and some love songs (chee-dee, chee-dee). I also heard a few territorial calls (chick-a-dee-dee-dee). The contact calls seemed to be a sort of "background noise," accompanying feeding and movement through the canopy of a stand of mature pines. The territorial calls and some louder chips were heard when I "pshh"ed in the vicinity of this small flock. I believe this sound works because it could represent a range of animals' alarm calls. It sounds kind of like a chipmunk or squirrel that is irritated about something. Small birds listen to one another and to other animals in their environment to detect danger or things out of the ordinary. This sound seems to replicate that type of cue, which explains why it can be met either with increased interest or a rapid departure from the area, depending on how it is perceived.

I noticed that contact calls generally accompanied movement from one foraging site to another, and that this movement sometimes seemed to involve wing flares that were more flashy than would simply be necessary for changing feeding location - this suggests to me that what I heard as "contact calls" can also serve an assertive function in establishing dominance hierarchies at food resources. Another sound that seems to serve a communication function was the drumming of a Pileated Woodpecker, which I heard at a distance but was still loud and clear. It must have found a good hollow tree to use as a drum. This sound communicates territoriality, which makes sense given the time of year, when birds are generally beginning to establish breeding and feeding territories.

A small Brown Creeper I observed made very high pitched, single notes (tseee, tseee). I thought I heard another individual responding, which suggests to me that these calls served a contact function. The Brown Creeper's foraging behavior involved frequent movement among small and medium sized trees, on which it spiraled up the trunk, apparently feeding on something in the bark. I did not quantify the intensity of this feeding, but it seemed somewhat desultory, especially given how much of the bird's time was spent calling and moving as opposed to feeding (about 2:1). I frequently saw the Brown Creeper in the same area of a tree as a BCCH, but they seemed to effectively partition the resource by utilizing different parts of the tree - the Brown Creeper stayed on the trunk, while the BCCH stayed on smaller side branches.

The behaviors observed in the Brown Creeper make sense given both the time of day and the time of year. In early afternoon on a bright, somewhat warm spring day, the Brown Creeper has presumably reached a positive energy balance and is now foraging to build up stores for night time. However, given the relatively mild weather and the length of the day now that we are past the equinox, it makes sense that the individual observed was using its time to move and call more than it was to feed. This has to do with the time of year - early spring - which in many passeriformes is a time for establishing beginning to attract mates and establish dominance hierarchies and breeding territories. Perhaps this Brown Creeper was starting to allocate more energy towards these activities, while still needing to feed enough to fuel its metabolism and begin to build stores for the energetically expensive business of mating that is soon to come. I will also note that at this point in the season, many of the most easily available overwintering insects and spiders found in tree bark may have been consumed, while the emergence of insects from their overwintering stage has likely yet to begin. So this is in all likelihood a time of some scarcity for the Brown Creeper - its frequent movement and its somewhat unfocused feeding may simply have been a reflection of food scarcity.

Two different plumages I observed were that of the Brown Creeper and the male Northern Cardinal. The brown creeper has a mottled brown and black pattern on its back. When it moves up the bark of a tree, it blends in so effectively that you can't even see it unless it's moving. This plumage is highly adaptive as a form of camouflage in the bird's feeding environment. It's also hard not to notice the pure white of its belly, especially when it flies. Perhaps this white is flashy enough to serve as a signal of attractiveness, and its location on the belly makes sense in this case because it is only visible when the bird is in flight (i.e. not foraging, when it wants to remain invisible). This plumage contrasts sharply with that of the male Northern Cardinal, which is about as conspicuous as could be. The bright red of the cardinal's feathers must serve as a mating cue, and certainly makes no effort to hide. Instead, in the dead of winter when nature is purely in shades of black, white, and brown, this red stands out like a sore thumb and must be associated with an early breeding/mate attracting season. It requires carotenoids from winter berries to maintain, so it serves a double function in that it makes creative use of a well-preserved winter food resource to indicate relative fitness.

Ingresado el 23 de marzo de 2019 por sam_blair sam_blair | 8 observaciones | 0 comentarios | Deja un comentario

18 de marzo de 2019

Field Observation 2: Physiology

On March 5th from 5:00 to 6:00 pm, Jess Savage and I made field observations at the Episcopal Diocese of VT trails leading to Lone Rock Point and North Beach. This area was south of the bay where I made observations for my first field journal. The temperature was ~16°F with moderate winds from the west and snow flurries initially light but increasing. By the end of my observations, light was just at the point of being able to see the trail.

The only birds I observed were a male and female Northern Cardinal, which I heard and then saw in a dense thicket of winterberry (Ilex verticillata), birch (Betula spp.), and cherry (Prunus spp.). According to the Cornell lab's online Birds of NA, cardinals preferentially consume fruits, seeds and insects, with "bills highly adapted for extracting seeds by cutting or crushing shells." In winter they consume 88% vegetable matter (ibid.). On the basis of this information I suspect that these cardinals were feeding on Ilex berries, and that the sheltered nature of this area may have enhanced its utility as both a source of food and a way to reduce convective heat loss, esp. on a windy night like this one.

I observed the cardinals at this site at 5:24 and again at 5:54. Berries found late in the season generally have a lower caloric content, with less fat and saccharides, which allows them to be better preserved. So the cardinals' ongoing presence and apparently intense and sustained foraging behavior could be explained by their need to consume a large volume of these berries, esp. as they prepared for the demands of nighttime thermoregulation.

Because light conditions were so low on my second observation, I wonder if the brush in fact served as the cardinals' roost site. When I observed them, the male esp. was acting very territorial, making "chips," and hopping through the underbrush and into an adjacent balsam fir (Abies balsamea).

Re the snag activity: I identified seven snags of varying sizes along my route. From bark, form, and nearby species, I was able to identify two as oaks, three as cedars, and two were unidentified. I found that larger snags had more cavities with a wider variability in size and shape. Many cavities in larger trees were oblong, indicating that they were the result of Pileated Woodpecker feeding. I thumped each snag thoroughly but didn't rouse anyone from their slumber. I did not notice any correlation between the location of the cardinals and nearby snags. They were actually in a brushy area in the middle of a field, with no nearby snags.

Snags are important for so many reasons! They provide food for decomposers, which return locked carbon and nitrogen to the soil. These decomposers, both on the bark surface and within the tree itself, in turn feed many spp, including woodpeckers, nuthatches, and brown creepers. Birds ike Pileated Woodpeckers also excavate nest cavities in snags. Once abandoned, these cavities are expanded on and utilized by chickadees, kinglets, and many other species as roosts for protection and to reduce heat loss during winter.

Ingresado el 18 de marzo de 2019 por sam_blair sam_blair | 4 observaciones | 0 comentarios | Deja un comentario

21 de febrero de 2019

2/14 Lone Rock Point

I observed a pair of Common Ravens flying to and from a roost site on a cliff in the vicinity of Lone Rock Point at dusk. I was lying literally two feet above them on the top of the cliff when they flushed from their perch, so I was able to observe their flight from a position directly level with them. When flushed, they took off using long, gliding wingbeats and banked around the edge of the cliff and out of site. ~20 minutes later, when they returned to the roost site, their flight was steady and level, with even and relatively rapid wingbeats that made a strong swooshing sound as they passed in front of me. Ravens' wings are broad and quite long, close in size to those of an accipiter, and they are able to use them for both gliding and flying (unlike crows, which generally do not soar). The individuals I observed clearly demonstrated the functionality of their wing morphology for multiple flight styles, both of which relate to their ecological niche - long, steady flight allows ravens to efficiently cover large areas in search of food, while agile maneuvering combined with intermittent soaring are used to defend territory, display to mates, and make use of hard-to-access nest sites.

Although I didn't see any other birds in flight during this walk, I did spend ~10 minutes listening to the behavior of a small chickadee flock in a mature coniferous stand as the sun was nearing the western horizon. The constantly shifting contact calls of these birds in the upper branches of white pine and hemlock suggested what I already knew about chickadee wing morphology and flight behavior. Chickadees are highly active and inquisitive feeders. Their wings are graceful, but shaped for bounding flight from point-to-point rather than the long, steady, occasionally gliding flight of the Common Raven. As such, they are shorter and more arced relative to the bird's body. When I got particularly close, I could actually hear the small sound of their wings beating. It is not hard to imagine the behavior that would produce this sound. The chickadees were hopping and flitting between branches, sometimes using their wings as airbrakes to briefly hover as they approached and then dangled from the tips of pine and hemlock cones. Observing chickadee behavior this winter, I've become quite familiar with the sound of chickadees foraging in this manner, and find that it is distinctive, even if contact calls or territorial "chick-a-dee" calls are absent. No other bird that I know of dangles from the underside of hemlock branches to feed from the cones - a distinctive behavior and habitat niche enabled by the chickadee's particular flight pattern.

It is altogether not too surprising that I didn't find many birds on this walk. I was out in the hour before dusk, a time for birds in winter to be finding shelter/sleeping sites and to be consuming energetic foods, if available. The exposed edge of Lake Champlain is a relatively barren and harsh site for birds in winter, especially compared with the feeders of suburban Burlington or the fruit trees of downtown. Early morning would be a better time to find birds in this area. Also, an approach through the Episcopal Diocese trails, which pass through a much wider variety of habitats and are generally more sheltered, would probably yield more sightings.

Ingresado el 21 de febrero de 2019 por sam_blair sam_blair | 3 observaciones | 0 comentarios | Deja un comentario

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