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Archive for May, 2009

Great Egret chicks.  Sarah Island, CLT, 2009

Great Egret chicks on Sarah Island (Photo © C. Trocki).

Wow!  What a day!

We spent today on Sarah Island (in Hingham Harbor) counting oodles and oodles of wading bird nests.

The preliminary final counts are as follows: 243 Black-crowned Night-Heron (BCNH) nests, 38 Snowy Egret (SNEG) nests, 72 Great Egret (GREG) nests, one unknown egret nest, two empty nests not identified to species,three nests identified as Glossy Ibis (GLIB) – but likely Great Egrets since no adult Glossy Ibis were spotted in the colony.   And… one nest with two BCNH chicks and two GREG chicks.  Go figure!?!

Wading bird nest with Black-crowned Night-Heron and Great Egret chicks.  Sarah Island, CLT, 2009.

Wading bird nest with Black-crowned Night-Heron and Great Egret chicks on Sarah Island (Photo © C. Trocki).

These numbers are quite a bit higher than detected in 2007, and are comparable to 2006 (though with somewhat fewer BCNH).

We worked very hard to move through the colony on Sarah Island today as systematically as possible.  We marked nest trees with water-based paint and numbered popsicle sticks with the hope of re-counting the colony to assess the reliability of our efforts.  However, given the amount of time that we spent (and disturbance we caused) in the colony today and the impending weather, I’m not sure we will have the opportunity to revisit this colony while active this year.  Things seem a bit ahead of schedule and there were many mobile BCNH chicks and some mobile GREG chicks present already – by next week I’m afraid that a visit to the colony would cause complete chaos and unnecessary losses.  If possible, I would like to revisit Sarah Island after the chicks have fledged in July/August to assess our ability to gauge nesting outcomes with a post-season visit.

Unfortunately, trips scheduled for Wednesday and Thursday of this week have been cancelled due to weather.  We head out next on Wednesday, June 3rd.  Have a great week – Carol

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We had another great day on the Islands yesterday! Sunny and beautiful – what luck for May!

We first landed on Middle Brewster Island, where we found only two Black-crowned Night Heron (BCNH) nests, one empty, in the elm grove on the southwestern portion of the island. There were also two active American Oystercatchers (AMOY) on the landing beach, slightly west of where we have seen them in recent years. A quick visit to the nest site turned up three young chicks!

On Outer Brewster, we conducted a more thorough search of wading birds nest sites than in the past. Polly stationed herself on the north side cliffs to count flushing adults while the rest of us moved through a small colony to the east of the landing beach and a larger colony in the center of the island.

Wading Bird Colony on Outer Brewster, CLT 2009

Polly obtained high counts of 38 BCNH, 8 Snowy Egrets (SNEG), 5-6 Great Egrets (GREG), and 16 Glossy Ibis (GLIB) in the area. Those of us on the ground counted a total of 37 BCNH nests, 12 SNEG nests, 6 GLIB nests, and one GREG nest. It is difficult to distinguish between the eggs and nests of the various species, so I strongly suspect we undercounted GREG nests in favor of BCNHs. But… it was a great practice round for Sarah Island next week, where nests are generally more visible, and the numbers are really pretty good. Most nests had eggs, but we did see at least one nest of young egret chicks and many BCNH nests with chicks ranging from recently hatched to less than one week old.

We also found another suspected American Crow nest while on Outer Brewster Island and noted a pair of territorial AMOY near the landing beach, though there was no evidence of an active nest.

From the boat we noted some limited Least Tern activity around the nesting beach on Lovells Island and will be sure to get back there in coming weeks. Another group of Common Eider chicks was spotted off of Middle Brewster Island, guarded by several Common Eider females but with adult breeding males nearby, which is unusual as males generally leave the area before the chicks hatch. We saw no AMOY on the south side of Lovells Island or the south side of Gallops Island on our way back in.

Have a great Memorial Day weekend!
-Carol

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Bunchberrys in bloomThings move fast in the Maine woods in spring.

The picture on the right is of bunchberries (Cornus canadensis) just starting to bloom on Schoodic Head here in Acadia National Park. It was taken early in the morning on May 20. (You can click on the picture to see a bigger version.)

The greenish/white things that look like flower petals are actually bracts — the actual flowers are clustered in the middle of these bracts.  More about them in a minute …

Bunchberries before bloomHere is a picture of the same plants, taken a week earlier.  I don’t know how long they had been up out of the ground when I took this picture — I do know that I was watching for this plant to get started (there is always a nice patch of bunchberries at the base of this tree, so it is something I keep a lookout for every spring).  Just a few days before I took this picture there wasn’t anything there. (Again, you can click on the photo to see a bigger version.)

The speed of spring’s onset here on the coast of Maine is pretty breathtaking.  Just a couple weeks ago, on April 30, there was almost no sign of spring, beyond grass growing.  The very first fiddleheads were just beginning to push their way up out of the ground.  Now there are flowers everywhere.

But when it comes to bunchberries, it’s not just their rapid growth in the first weeks of May that gives them a claim to being fast.  The real speed is in the opening of the flowers.  Again — the flowers are the tiny green balls gathered in the center of the white bracts.  You can see them pretty well if you look at the bigger version of the first picture.

Joan Edwards, a botanist, and Dwight Whitaker, a physicist — both from Williams College — teamed up to create a high speed video image of the opening of bunchberry flowers. They claim that it is the fastest flower on earth, opening in 0.4 ms — less time than it takes for a bullet to travel the length of a rifle barrel. The pollen released in this explosive opening accelerates at a rate that is 800 times that of astronauts during liftoff.  According to Edwards and Whitaker:

Explosive flowering enhances insect pollination in two ways. First explosive flowering reduces the amount of pollen eaten by the insects because the pollen spray from the explosion disperses the pollen on insects’ bodies and the high speed of the pollen imbeds it deep in the insects’ hairs where it is less likely to be gathered and eaten. Second, explosive flowering limits pollinators to insects heavy enough to trigger the flower. Large flies, bumblebees and beetles are large enough to trigger flowers and move rapidly between inflorescences, whereas ants and small flies, which often stay on one inflorescence, cannot trigger the flowers.

Edwards and Whitaker, assisted by Sarah Klionsky and Marta Laskowski, published their bunchberry findings in Nature.  For more information see http://www.williams.edu/Biology/explodingflower/.

For more information about bunchberries see http://plantwatch.fanweb.ca/plant-information/bunchberry.

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We had a great start to our coastal breeding bird monitoring field work yesterday (5/19/09) with a calm and sunny morning at Boston Harbor Islands!

Boat-based gull and cormorant estimates for the Outer Islands appear, at a glance, to be comparable to previous years.  In an effort to verify our counts, I’m working on capturing digital photographs of the colonies from the boat so that I can carefully count, after the fact, in the relative comfort of my office (not that we all wouldn’t miss counting from a rocking boat in the cold….). Yesterday’s pictures look pretty good and I’ll be working on the numbers in days to come.

During our boat-based gull and cormorant counts, we also detected an incubating American Oystercatcher on Calf Island, as well as single American Oystercatcher present on both Outer Brewster and Little Brewster Islands.  There were lots of male Common Eider still in the area and we saw several groups of female eiders with young chicks already on the water.  I do not have any records of eider chicks this early in 2007 or 2008, so it does seem like things are a bit ahead of schedule this season (at least for eider).  Four Great Cormorants and a flock of Purple Sandpipers were other items of note.

A thorough search of the south side of Calf Island turned up 38 Black-crowned Night Heron nests, most with 3-4 eggs, but several with young chicks.   A FULL nest of American Crow chicks were also found in the large willow on Calf Island.  I climbed up to get a look in a large stick nest approximately 15 feet up – imagine my surprise when it was full of black crow babies instead of blue eggs!   Unfortunately, I left my camera down below.

However, while circling back to the landing beach on Calf, we scanned the shoreline for the nest of the incubating oystercatcher previously spotted from the water.  This is what we discovered…

A brand spanking new American Oystercatcher chick.

We cleared the area quickly and watched from a distance as the vigilant parent dive-bombed a couple of gulls and returned safely to her nest. (If you see him, ask Tim about his pitching arm – predatory gulls, beware!)

Looking forward to another great season!

–Carol

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Heron’s lay blue eggs. I knew that the eggs of American Robin’s were blue, and a quick Google search indicates that European Starlings and Bluebirds also lay blue eggs (I probably should have seen that last one coming), but I hadn’t heard about blue Heron eggs. Like a proverbial 4-year-old, this observation sparks the question–why?

Black-crowned Night Heron chich and (blue!) egg (C. Trocki).

Black-crowned Night Heron chick and (blue!) egg (C. Trocki).

Why are heron eggs blue?

Conveniently, Rob, a volunteer with the Boston Harbor Islands Coastal Breeding Bird Monitoring Program, had asked that question of Carol, the project’s lead scientist, just the other day. Here’s her reply:

“I did a little digging about Rob’s question – why are heron eggs blue?  I didn’t come up with much other than the sketchy explanation I offered yesterday… most solid blue eggs belong to birds that have open nests in trees.  It is thought that the blue eggs might offer some cryptic advantage from avian predators that are viewing them from the air.  I guess the idea is that the blue eggs in stick nests may appear as regular openings (sky) seen through dense vegetation.  Seems a bit weak, but I haven’t come across anything better….

Another theory is that the color may serve as a cue for males to assess the health and fitness of females.  The pigment that creates the blue coloration is nutritionally derived, so the bluer the eggs the healthier the female who laid them.  So a healthy female, capable of provisioning well for herself and her young should need little assistance from the male (always looking for the easy way out!).  This explanation seems even more sketchy to me and has little evidence to back it up so far.”

Blue eggs in a tree nest (C. Trocki).

Blue eggs in a Common Grackle nest in a tree on Middle Brewster Island (C. Trocki).

Intrigued? Want to know more? Carol recomends a 2006 article by R. M. Kilner:

Kilner, R. M. 2006. The evolution of egg colour and patterning in birds. Biological Review 81:383-406

Wondering who an egg belongs to–blue or otherwise? I suggest “A Guide to Nests, Eggs, and Nestlings of North American Birds” by Paul Baicich and Colin Harrison.

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They are men on a mission: to sample water quality and flow characteristics of streams, rivers, and ponds in northeastern parks….and the crab cake panini at the Main Streets Market and Cafe in Concord, MA. Meet Eric and Dan, the dynamic duo who will be visiting a park near you (provided you live near a national park in VT, NH, MA, CT, NY, or NJ) with a cooler full of sample vials, a high-tech probe (the “YSI”) that measures everything from dissolved oxygen to pH, a fancy “flow-meter” that builds a profile of how water flows through the stream channel, and a yet-to-be-named (suggestions welcome) inflatable “research vessel”.

Eric and Dan hail from the University of Vermont’s Rubenstein School of Environment and Natural Resources. Eric is pursuing a master’s degree and Dan is a research associate.

Eric and the YSI at Saint-Gaudens NHS

Eric and the YSI at Saint-Gaudens NHS

Dan blowing up the "research vessel" at Marsh-Billings-Rockefeller NHP (NPS photo).

Dan blowing up the "research vessel" at Marsh-Billings-Rockefeller NHP (NPS photo).

Recently, I headed out in the field to learn the tricks of their trade. Eric and Dan boast of supernatural powers–or uncanny luck–for heralding good weather; in two summers together they have logged only two rainy days. This trip was true to form. Despite an ominous forecast, we had two surprisingly sunny days in the field together sampling streams and ponds at parks in Vermont, New Hampshire, and Massachusetts. Some, like Blow-me Down Brook at Saint-Gauden’s NHS, were tranquil and serene. Others, like one of the streams we sampled at Minute-Man NHP, were clearly impacted by the suburban landscape in which the park is located. The experience reminded me: We all live downstream and national parks are no exception. The water resources in national parks, especially smaller units like the ones in the northeast, are affected by the communities and landscapes around them. The data Eric and Dan collect will help parks and their surrounding communities understand what kinds of water-quality issues they face, and maybe help guide solutions.

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