Galápagos Trip

By in Trip Report, Uncategorized

You may have read my post from last spring in which I described a wonderful trip I took to the Galápagos Islands in March 2010.  Along with my colleague Sarah Gibbs, we took a class of 24 Colby students to those wonderful islands.  I was able to visit two islands that I had not visited earlier.

We flew from Quito to the airport on San Cristóbal.  The immigration line extended out of the small terminal.  That wait allowed us to watch a pair of Cactus Finches building a nest in a large cactus adjacent to the terminal.  The Cactus Finch is one of 13 species of Darwin’s finches, found only in the Galápagos.

We took a bus ride into Puerto Baquerizo Moreno, the main town on San Cristóbal, and checked into our hotel.  A Chatham Mockingbird was perched on the windowsill of my room.   Four endemic mockingbirds occur on the Galápagos and the Chatham Mockingbird is only known from San Cristóbal.

That afternoon, we took a long hike along the coast to some highlands.  Both Magnificent and Great Frigatebirds were nesting near the tops of some cliffs.  Small Ground Finches and Medium Ground Finches were common.  Along the shore, we saw Lava Gulls, Brown Pelicans, Striated Herons, Ruddy Turnstones, hundreds of Galápagos Sea Lions and many Marine Iguanas.

The next morning, we boarded a couple of boats for the two-hour crossing to the islands of Santa Cruz.  Along the way, Galápagos Shearwaters and Eliot’s Storm-Petrels were common.

Our first stop on Santa Cruz was the Charles Darwin Research Station where captive breeding of Galápagos tortoises is ensuring the survival of these behemoths.  On the grounds, we saw Large Ground Finches, Small Ground Finches, Galápagos Flycatchers and Galápagos Mockingbirds (this mockingbird is found on a number of the Galápagos Islands).

After lunch, we visited Los Gemelos (the twins), two massive depressions at higher altitude.  We were treated to several gorgeous Galápagos Doves, Warbler Finches and a fly-by Dark-billed Cuckoo.   We had a look at a perched cuckoo and a Smooth-billed Ani later in the day when we visited some lava tunnels tall enough to easily walk through.

We had an early start the next day for a cruise to the extremely arid island of Bartholomé.  The sea was calm and the day was sunny.  From the boat, we saw Eliot’s Storm-Petrels, Red-billed Tropicbirds, Nazca Boobies, Blue-footed Boobies, Brown Noddies and massive flocks of Red-necked Phalaropes.  We saw several Swallow-tailed Gulls perched on the cliffs of Daphne Major when we sailed close by this small island. Manta Rays occasionally jumped out of the water for memorable views.

On Bartholomé, we saw Lava Herons, American Oystercatchers and lots of Blue-footed Boobies.  A Galápagos Hawk soared over the island and was later perched at the pinnacle of the island.  Snorkeling provided views of a diversity of fish as well as sea turtles.

We returned to Santa Cruz, exhausted but exhilarated.  The following morning we were back on boats to the island of Isabela, the largest island in the archipelago.  Approaching from the south, this island had a distinctly different feel.  The sand was white, not gray as we had seen on other islands.  Mangroves ringed the shoreline and the water was a beautiful blue-green.  I could have been convinced I was in the Caribbean except for the fact there were Galápagos Penguins swimming around the boat and dock!   We later got to see a number of penguins and Blue-footed Boobies up close and personal.

A bus excursion that afternoon included a stop at a large lagoon where American Flamingoes, White-cheeked Pintails and Common Moorhens were feeding.  The flamingoes were magnificent!

The next morning we boarded an open-air bus to the trail head for Cerro Negro, one of the five major volcanoes on Isabela.  Cerro Negro was last active in 2005.   Our ultimate goal was to climb Volcán Chico, a parasitic volcano on the side of Cierro Negro.  The hike was a round-trip of 12 miles.

The views of the caldera of Cerro Negro were amazing; the caldera is about seven miles across and we could see where the lava from the 2005 eruption had killed some of the vegetation in the caldera.

Small Tree-Finches and Large Tree-Finches were seen along the hike to Cerro Negro.  Vermilion Flycatchers cooperated nicely for everyone in the class.  A few of us got to see Galápagos Martins, hawking insects over the caldera.

For more details and pictures from our trip, please visit our blog: http://web.colby.edu/galapagos/2011/

[First published on April 3, 2011]

Turkey Vulture

By in Species Accounts, Uncategorized

A half century ago, birders eagerly awaited the first of the spring migrants into Maine in March.  The arrival of Red-winged Blackbirds, Common Grackles and American Woodcock served as harbingers of spring.  Now we have added Turkey Vulture to that list of early migrants into Maine.

Turkey Vultures are easy to identify in the air as they soar with their wings held in a shallow V.  Mostly brownish, Turkey Vultures have distinctive two-toned underwings.  The underwings are mostly white except for a black patch on the inner forward part of the wings.  Turkey Vultures often seem to rock from side to side as they soar.

Turkey Vultures are common enough now in Maine during the breeding season that sightings are frequent and unremarkable.  However,  Ralph Palmer wrote in Maine Birds, published in 1949, that Turkey Vultures are rare in Maine.  Palmer lists only 12 records over the period of 1862 to 1944.  A Turkey Vulture sighting 50 years ago would have produced great excitement among birders.

The increase in Turkey Vultures from a rarity to a common breeding species in Maine mirrors a more general pattern of range change.  The range of the Turkey Vulture is huge, extending from the Prairie Provinces of Canada to the southern tip of South America. Along the Californian coast and much of the southeastern United States, Turkey Vultures are year-round residents.

During the 1960s and 1970s, North American populations of Turkey Vultures shifted with western and southern populations declining as New England and Midwest populations began to increase.  The over-all population has been increasing at a rate of about 1% per year since 1966.

Turkey Vultures are scavengers.  The lack of feathers on their head is surely an adaptation to maintain cleanliness.  Sticking a feathered head in a rotting carcass would certainly foul the feathers.

Turkey Vultures therefore play a role in removing and recycling dead animals.  They will only rarely kill their own vertebrate prey.  Even then, the prey has to be defenseless.  The Black Vulture, a related species rarely found as found north as Maine, regularly kills defenseless prey, like newborn mammals or birds.

Even though Turkey Vultures pose no threat to newborn livestock (like Black Vultures), they have been persecuted by farmers.  Some farmers destroy Turkey Vultures because of a supposed role in spreading hog cholera bacteria and other livestock diseases.  The scientific support for the spread of diseases by Turkey Vultures is very weak.  In short, we should let Turkey Vultures be.

How do Turkey Vultures find carrion?  Unlike Old World Vultures and the Black Vulture that rely on sight to find a carcass, Turkey Vultures rely first and foremost on their sense of smell.  Turkey Vultures are aerial bloodhounds!  The ability to track food by smell means that Turkey Vultures can find food in densely forested areas where the canopy prevents visual recognition of prey.  Turkey Vultures do have good vision as well, which certainly can be used to find carrion in open areas.

The diet of Turkey Vultures is broad.  Mammal carrion is the most common food, ranging from mice and shrews to deer and moose.  Carrion of livestock is used widely in agricultural areas.  For instance, Turkey Vultures in southern Pennsylvania eat mostly dead domestic stock (68% of their diet), including dead pigs and piglets, calves, sheep and kitchen scraps.  Other food taken includes dead alligators, turtles, snakes, tadpoles, frogs and even some invertebrates (crickets, shrimp, stranded mussels).

Turkey Vulture wings are well adapted for thermal soaring.  The wings are broad and the primary feathers, the large feathers at the tip of the wing, are slotted to allow rising air to pass over them to generate lift.  The thermals that Turkey Vultures use are usually caused by uneven heating of the land.  The air above a landscape feature that heats up rapidly expands and rises, to be replaced by air from surrounding cooler areas.  In turn, this cool air is heated and then rises as well.  This situation results in a sustained vertical wind as long as the sun is high in the sky.  Updrafts caused by mountains or large buildings can generate updrafts as well.

You will usually not see a Turkey Vulture in flight before mid-morning.  It takes a while for the sun to generate enough heat to cause thermals to form.  Turkey Vultures generally do not ascend to great heights in a wintering or breeding area.  It’s harder to pick up the smell of carrion from great heights.  During migrations, Turkey Vultures depend on thermals and migrate by gliding rather than flapping.   Some vultures have been reported at heights greater than three miles high!

[First published on March 20, 2011]

Review of the Crossley Identification Guide

By in Book Reviews, Field Guides, Uncategorized

Over the past 25 years, an embarrassment of riches has become available for the education of birders.  Dick Walton and Bob Lawson’s Birding by Ear tapes and now CD’s allowed birders to make huge leaps in the ability to identify birds by ear.  David Sibley’s 2000 book, The Sibley Guide to Birds took the field guide to a new level.  More specialized books on the identification of difficult groups like gulls, sparrows, shorebirds and hawks have enriched our libraries in the past decade.

The latest major contribution to bird identification is The Crossley Guide: Eastern Birds written and assembled by Richard Crossley.  The assembly I refer to is made possible by the ease with which one can manipulate digital images.  In this book, Crossley presents 10,000 pictures of the birds of eastern North America.

The bulk of the book is 640 plates, each devoted to a single species, in which Crossley pastes in photographs of the species over a photograph of the habitat of the species.  The composite plate is not intended to try to create the illusion of a single photograph but rather is an effective way to associate bird with habitat.

Some of the photographs are close-ups while others are more distant.  Sometimes side views are shown and in other cases back or front views.  Some birds are perched and some are flying.  Different plumages by age and sex are provided.

As an example, the Peregrine Falcon plate has an urban landscape with skyscrapers for the background (Peregrines do well in New York City and other metropolises with a near endless supply of pigeons to feed on).  Superimposed on the background are 15 photos of Peregrines.  One is in a stoop (watch out, pigeons!), one is flying directly toward you, and one is just a distant silhouette.  Perched adult and juvenile falcons are shown.  In short, you see Peregrines from many angles and distances, just like you would in the field.

I know an ornithologist from Washington state who holds that to really be proficient at field identification of birds, you must be able to identify a bird from five angles: from the front, from the back, from the side, from the underside in flight and from the upperside in flight.  Crossley’s book has all of these views for some of the species he covers.

The geographic scope covers eastern North America westward through the Great Plains.  The coverage ends at about the western boundary of Oklahoma, Kansas, Nebraska, the Dakotas and Saskatchewan.  The coverage of the species in this guide is exhaustive.  In addition to the common birds like Northern Cardinal, full coverage is given to eastern vagrants like Swainson’s Hawk, Sage Thrasher and Green-tailed Towhee and to ultra-rarities like Fieldfare, White-throated Thrush and Yellow-faced Grassquit.

The many images provide a rich resource for even the most seasoned birders.  My wife pointed out the red lores of a Snowy Egret in one of the photographs.  This color appears briefly early in the breeding season.  I had never seen this feature nor even been aware of it.

The plate takes up the bulk of the space for each species.  A small distribution map and telegraphic text on behavior and identification are provided as well.  Crossley also gives the four-letter code for each species that bird banders use.  As a bander, I have used these codes for years for efficient note-taking.

The vast majority of photographs are crisp and pleasing; some are truly stunning.  I am glad that the format of the book is large enough to ensure that details can be seen in the photographs.  I own other bird and insect photographic guides where the images are so small as to be nearly unusable.

The beginning of the book has the usual information on bird topography and molting.  Crossley also describes his idiosyncratic (to me, anyway) of identifying birds.  In order of importance, he lists these key features: shape, size, behavior, probability (is the presumed species expected here at this time of year?), color and finally voice.  I elevate the importance of voice to near the top of my list but it is interesting to read Crossley’s reasons for ranking the features.  To facilitate size comparisons, Crossley has photographs at the same scale of birds of each group at the beginning.  It is easy to see how much larger a Purple Martin is than a Bank Swallow.

Measuring seven by ten inches, this wonderful guide will be difficult to carry in the field.  Keep it in your car or backpack though.  This guide is a wonderful addition to the birding literature.

[First published on March 6, 2011]

Highlights of Maine Christmas Bird Counts – II

By in Christmas Count Summaries, Uncategorized

This column is the second of two in which I review the highlights of some of the Christmas Bird Counts conducted in late December to early January in Maine.  Today’s column will concentrate on coastal counts.  We’ll start in York County and work our way downeast to Machias.

The York County count, the southernmost of all the Maine counts, had a nice total of 89 species.  With so much open water, coastal sites generally have more waterfowl in the winter than inland sites.  That pattern held for York County as 18 species of ducks and geese were tallied.  Highlights were a pair of Gadwall and five Green-winged Teal.  Canada Geese were abundant with over 1100 counted.

Both Great Cormorants (43) and Double-crested Cormorants (a new high count of 59) were present.  For shorebirds, 10 Dunlins joined the more expected Sanderlings and Purple Sandpipers.  Other notable sightings were three Dovekies (always a good sighting from shore) and 132 Razorbills.  Lingering migratory birds included a Great Blue Heron, a Northern Flicker, a whopping 62 Eastern Bluebirds, a Hermit Thrush, single Orange-crowned, Palm and Yellow-rumped warblers, a Savannah Sparrow and a dozen Common Grackles.  Quite a count this year!

The Biddeford-Kennebunkport count produced a list of 80 species.  A Cackling Goose was picked out of the 653 Canada Geese seen.  The nine Harlequin Ducks and 1,320 Mallards were record high counts.  Loons and grebes were unusually abundant: 151 Common Loons, 235 Horned Grebes and 178 Red-necked Grebes.  High counts for some woodpeckers were set with 123 Downy Woodpeckers, 71 Hairy Woodpeckers and 11 Pileated Woodpeckers.  The 238 Tufted Titmice set a high record as well.

Lingering birds included two Great Blue Herons, four Northern Flickers, six Carolina Wrens, 13 Eastern Bluebirds and nine Common Grackles.

The Portland Count took pride of place with the highest number of species (107) of any count this season in Maine.  Significantly, four species were found for the first time on this count: Greater White-fronted Goose, Eurasian Wigeon, Northern Shoveler and American Woodcock.

A few species were particularly abundant this year, yielding the highest number of each species in the past 30 years.  These included 1,830 Mallards and 245 Common Loons.

A remarkable 26 species of waterfowl were tallied this year, highlighted by the species listed above as well as by two Wood Ducks and two Redheads.

The list of lingering species is long.  Most of the following individuals either moved on to more southerly climes or perished as winter set in over the past five weeks: a Killdeer, two Northern Flickers, a Winter Wren, two Ruby-crowned Kinglets, a Gray Catbird, a Common Yellowthroat and a Yellow-breasted Chat.

The Freeport-Brunswick count produced a list of 63 species.  Highlights were record high counts of Common Eider (473), Long-tailed Duck (287), Glaucous Gull (5), Pileated Woodpecker (18) and Bohemian Waxwing (312).

Unusual species included a Killdeer, a Northern Flicker and a Gray Catbird.  A Dickcissel present in the area was bashful on the day of the count.

Thomaston-Rockland counters found 79 species.  The 396 Common Eiders, 949 Herring Gulls and 14 Great Black-backed Gulls were much less common than in previous years.  However, the 114 Bald Eagles, 124 Red-necked Grebes and 45 Tufted Titmouse were found in unprecedented abundance.

Other highlights were a Red-shouldered Hawk, a Merlin, two Peregrine Falcons, 32 American Coots, a Black-headed Gull, a Long-eared Owl, a Pine Warbler, three Swamp Sparrows and a hardy Red-winged Blackbird.

On to the Belfast region of Penobscot Bay where counters found 67 species.  Common Goldeneyes put in a strong showing (1001 individuals) with 11 Barrow’s Goldeneyes sprinkled in among them.  Seven Great Blue Herons and a Belted Kingfisher were remarkable finds.

The counters saw an American White Pelican during the week of the count, but not on count day.  Interestingly, several of these pelicans were seen last month in the Boothbay region.

The Schoodic Peninsula count produced a list of 66 species.  Highlights included record high counts of 97 Black Guillemots and 188 Mourning Doves.  Two Boreal Chickadees were mixed in with the 80 Black-capped Chickadees.

Fewer lingering species were noted here: one Great Blue Heron, one Belted Kingfisher and two Rusty Blackbirds were highlights.

The Machias-Jonesport count yielded a total of 55 species.  The eight Brant represented an excellent count for this portion of the coast.  The 24 Harlequin Ducks and 609 Long-tailed Ducks set new high-count records.

A Spruce Grouse was a nice find.  Lingering birds included a Great Blue Heron and nine Common Grackles.

[First published on February 20, 2011]

Highlights of Maine Christmas Bird Counts – I

By in Uncategorized

The annual Christmas Bird Count sponsored by the National Audubon Society occurred over the period December 14, 2010 until January 5, 2011.  As is my custom, I will devote a couple of columns to highlights of the counts in Maine.  Today we will consider some representative inland counts.

Let’s start with the Misery Township Count, held in the vicinity of the Forks, south of Jackman.  This count usually has the most severe winter of any count in Maine and usually the lowest species diversity.  That pattern held this year as only 18 species were tallied.  However, the quality of those birds was high.  Sixteen Gray Jays were found, almost outnumbering the 19 Blue Jays on the count.  One intrepid Mourning Dove was found and a single Ruffed Grouse.  Red-breasted Nuthatches outnumbered White-breasted Nuthatches, 31 to 5.  This result was not unexpected, as Red-breasted Nuthatches prefer the coniferous habitat that dominates the Misery Township region.

So far this winter, relatively few of the northern finches have moved south into northern New England.  The only ones on this count were 19 Pine Grosbeaks and 44 Common Redpolls.

The Waterville count produced 56 species.  Most still water was frozen over but the Kennebec River and some tributaries produced nine species of waterfowl, including an American Wigeon, four Ring-necked Ducks and a Barrow’s Goldeneye.  An American Coot was the first ever reported for the Waterville count.

An American Kestrel, five American Robins, a Savannah Sparrow, a Carolina Wren, three Brown-headed Cowbirds and two Common Grackles were lingering in central Maine later than usual.  Counters found 63 Common Redpolls and three Pine Siskins.  A Red-bellied Woodpecker was a nice find.

A mere 30 miles west of Waterville, the Farmington count usually produces fewer species than the Waterville or Augusta count.  The 30 miles results in a slight but significant change in the severity of the winter for the Farmington area.  This year 37 species were counted.  With all the water frozen over, no waterfowl were found.  Lingering individuals included two American Robins, three Rusty Blackbirds, one Common Grackle and most surprisingly, one Northern Flicker.

The count of 146 Common Redpolls was a nice but not surprising total; Farmington regularly is a stronghold of redpolls.  Thirty-eight Bohemian Waxwings made a nice addition to the count.

The Bangor Count produced 54 species.  Nine species of waterfowl were impressive with the highlights being a Wood Duck and seven Red-breasted Mergansers.  Perhaps even more impressive were six species of diurnal raptors including an Osprey, a Merlin and a Peregrine Falcon among the more expected Bald Eagle, Red-tailed Hawks and Cooper’s Hawks.  Since Ospreys are absolutely dependent on open water to fish, we can presume that this daring Osprey has moved on or perished now that winter has a firm hold on our state.

Species that were seemingly overstaying their welcome included a Northern Flicker, an Eastern Bluebird and nine Northern Mockingbirds.  Bohemian Waxwings were well represented with 189 of these crested beauties counted.  83 Northern Cardinals made for an impressive total.  Six species of finches were found including five Pine Grosbeaks, eight Purple Finches (scarce this winter in Maine), 186 Common Redpolls and 10 Pine Siskins

Just eight miles to the north, the Orono-Old Town count yielded just 43 species.  Nothing on the list jumps out to me as unusual although the 130 Wild Turkeys and three Gray Jays were nice totals for this area.  Just 30 European Starlings were found compared to the 993 in Bangor.

Moving to the south, the Lewiston-Auburn count resulted in a final tally of 52 species. Without a doubt, the highlight of the count was a Lark Sparrow.

The seven species of waterfowl included an American Wigeon and 40 Greater Scaup.  Four Common Loons and a Pied-billed Grebe were excellent finds for this time of year in inland waters.

The L/A counters hit the trifecta with the accipiters: one Sharp-shinned Hawk, two Cooper’s Hawks and a Northern Goshawk.  Half-hardy species included 19 American Robins, five Northern Mockingbirds and three Rusty Blackbirds.  Two Cedar Waxwings were found among the 250 Bohemian Waxwings.  Fifty Common Redpolls and two Pine Siskins were good discoveries.

Finally, the Sweden count produced 32 species.  Bohemian Waxwings were scarce with 11 found.  A single House Finch was counted along with 88 American Goldfinches and 102 Common Redpolls.  Fifteen crossbills were found but could not be identified to species (either Red Crossbills or White-winged Crossbills).  This winter so far is shaping up as a poor crossbill winter so these 15 birds were excellent finds.

[First published on February 6, 2011]

Common Raven

By in Species Accounts

One of the joys of Maine is seeing or hearing a Common Raven.  These massive birds belong to the perching birds or passerines, the largest order of the birds.  All passerines have three toes pointing forward and one pointing backward, adapted to hold on to a branch or other support for perching.  We normally think of perching birds as small creatures like chickadees, goldfinches and sparrows.  With a wingspan of more than four feet and a weight of three pounds, the Common Raven is the biggest perching bird in the world.

The Common Raven is widely distributed in the Northern Hemisphere, ranging from north of the Arctic Circle to the mountains of Central America.  The black plumage and large size of these birds make them conspicuous birds, particularly in winter.  The raven figures prominently in the folklore and mythology of many northern peoples.   Many early peoples associated the raven with death.  This association is perpetuated in Edgar Allen Poe’s well-known poem, “The Raven”.

Although the Common Raven is larger than a Red-tailed Hawk, ravens lack the strong bill and long, sharp talons to kill their own prey.  As a result, ravens depend on carrion for most of their food.  In the winter, when a dead animal is likely to be frozen, ravens have difficulty in opening the corpse to feed.  They must depend on coyotes and other scavengers to tear through the skin of a frozen animal.

The behavior of Common Ravens is winter has been the focus of a decades-long study by Dr. Bernd Heinrich of the University of Vermont.  Heinrich has a camp near Mount Blue where this research project is based.

The project began one October many years ago when Heinrich observed a small group of ravens which had just located the carcass of a moose.  This moose represented many meals for the ravens, enough to keep them well-fed for many months.  Oddly, the ravens were quite loud, giving penetrating calls which resulted in other ravens coming to the carcass.  Why would the ravens that found the moose want to share their feast?  Why should ravens be unselfish?  Wouldn’t it be better to be quiet and keep the moose meat for themselves?

Heinrich describes his research in the book “Ravens in Winter”.  The book reads like a biological detective story as Heinrich seeks to understand why ravens would show apparent unselfish behavior

The paradox was resolved only after Heinrich began to capture ravens and tag them with numbered plastic wing tags.  This tagging allowed him to recognize individual ravens from day to day.

This biological mystery was solved by first noting that a mated pair of ravens (they pair for life) defend a territory throughout the year, not just in the summer as most of our perching birds do.  This territorial pair defends their turf vigorously and will chase off any intruding raven.

From this observations of banded birds, Heinrich realized that the ravens which called to alert other ravens to the presence of an animal carcass were unmated juveniles.  These birds did not have a breeding territory and wandered widely.

If a wandering juvenile located an animal carcass in the territory of a mated pair, the territorial birds would soon locate the intruder and the food and chase the intruding raven off.  That observation is the key to the story.  By advertising the presence of the carcass to other juveniles, the number of juveniles at the food overwhelms the territorial pair.  The mated pair cannot chase off all the juveniles.  As soon as one is scared off, others are back feeding on the carcass.

Behavior which appears at first to be unselfish is, in fact, self-serving behavior.  If a juvenile raven found a carcass and kept quiet, it would be evicted as soon as the territorial ravens found it.  By recruiting other juveniles to the carcass, the juveniles can have the food for themselves because their numbers prevent the resident pair from chasing the juveniles away.  It is only by sharing that the juveniles can be assured of a feast, not unselfish behavior at all.

Sadly, the book is now out of print but is commonly available from used book-sellers.  However, a more recent book, The Mind of the Raven, is still in print.  In this book, Heinrich explores the remarkable intelligence of ravens.  Ravens use tools and have remarkable abilities in problem-solving.  Their vocal communication is complex.

Years ago, researchers described Common Ravens repeatedly sliding on their backs down a muddy embankment.  The authors could not explain this behavior except as a form of entertainment.  You have to love birds that like to play!

[Originally published on January 22, 2011]

Misleading Bird Names

By in Uncategorized Tags:

What’s in a name?  As far as the common names of North American birds are concerned, a lot of history is in a name.  However, that history often contains misleading or, in some cases, inaccurate information.

The idea for this column came while looking for American Tree Sparrows recently on the Waterville Christmas Bird Count.  The sparrows are usually either on the ground or in short shrubbery, like any self-respecting sparrow.  American Tree Sparrows do nest on the edge of the tundra where there are scattered trees.  True tundra is treeless.  Throw in a tree or two at the edge of the tundra and you have a suitable nesting area for these birds.

From the time of the first ornithologists in North America like John James Audubon, Alexander Wilson and Mark Catesby until well into the 1900’s, ornithology was practiced with the aid of a shotgun rather than binoculars and spotting scopes.  Bird identification was done using stuffed specimens, which were (and still are) stored in cabinets with drawers.  The stuffed specimens are typically stored with the upper side of the bird down.  When a person pulled out a drawer to study the specimens, the underside of the bird would be seen first.

The initial focus on the underside of a bird has resulted in some rather curious common names for birds.   One of our most common breeding ducks is the Ring-necked Duck.  Yet, how many have seen a ring around the neck of this duck?  I know I rarely see this mark out in the field.  A male in breeding plumage has a dark chestnut collar around the lower part of the neck.  This characteristic would be seen by ornithologists pulling out a drawer of Ring-necked Ducks lying on their back but this characteristic is not very useful for field identification.  I think Ring-billed Duck would be a better common name.

The Red-bellied Woodpecker is a common bird throughout the southeast quarter of North America.  The species is expanding northward and has become a regular if quite uncommon part of the Maine avifauna.

If you look at a picture of a Red-bellied Woodpecker you see a bird with a striking ladder-backed dorsal surface and bright red on the nape and top of the head.  The red belly is hard to see in the field.  It’s typically hard to see the underside of any woodpecker in the field.  But the belly is in fact tinged with red and that feature was obvious to museum ornithologists.

The Evening Grosbeak has one of the most curious and misleading common names.  This large, colorful finch is active throughout the day and goes to roost in the evening like other members of the finch family.  The common names commemorates the erroneous description made by a Major Delafield, a United States boundary agent in 1823:

“At twilight, the bird which I had before heard to cry in a singular strain, and only at his hour, made its appearance close by my tent, and a flock of about half a dozen perched on the bushes in my encampment . . . . My inference was then, and is now, that this bird dwells in such dark retreats, and leaves them at the approach of night”.

Other common names give misleading indications of the distribution of a species.  The Cape May Warbler breeds around the margins of bogs in the northern tier of states as far west as Minnesota and throughout much of the eastern two-thirds of Canada.  To see this species in Cape May, New Jersey, you would need to visit in the late spring or, better yet, early fall, when these birds are migrating through between northern breeding grounds and the wintering grounds in the West Indies.  The common name simply represents the site where the first museum specimen (called the type specimen) of this bird was collected.

In similar fashion, you have little chance of seeing the Tennessee Warbler or Nashville Warbler in Tennessee except during migration.   Don’t look for breeding Philadelphia Vireos in Pennsylvania or Connecticut Warblers in Hartford.  The type specimens for all of these birds were taken during the migration season in the locality commemorated by the common name.

The Palm Warbler has one of the northernmost breeding ranges of all our warblers. So, why then is the Palm Warbler named after a tropical tree?  In this case, the bird is named after its preferred habitat during the wintering season.  Palm Warblers winter in Florida, along the Gulf Coast and in the West Indies where they often are associated with palm trees.

[First published on January 9, 2011]

Bird Muscles

By in Physiology

Many of you will have eaten turkey over the Thanksgiving holidays.  Some people prefer white meat while others prefer dark meat.  What is the difference?

Dark meat is composed of red muscle fibers (cells).  The red color comes from a high concentration of myoglobin in the fibers.  Myoglobin, like the hemoglobin in our red blood cells, binds oxygen that can be released as needed to the muscle fibers to allow them to contract.  The myoglobin increases the entry of oxygen to the muscle fibers.  Contraction of muscles allows for such useful activities as walking, flying and capturing food. Red muscle also has an abundance of capillaries to help provide oxygen to the fibers.

Red muscle fibers are quite narrow and so have a very high surface area relative to their volume.  As a result, oxygen does not have to move very far as it diffuses into the muscle cells.  The flight muscles of small songbirds (and small bats) have the highest aerobic capacity of any vertebrate species.

Red muscle fibers are often referred to as slow twitch fibers.  The fibers contract but at a relatively slow rate.  The fibers require lots of oxygen to do their work but his oxygen is provided by the blood and stored in the myoglobin until needed by the muscles.  As a result, red muscles can do slow but steady work; they do not tend to fatigue.  Red muscles are excellent for sustained flight.

The breast of a turkey, on the other hand, is made up of white muscle fibers.  These muscles are not well supplied with capillaries and do not contain much myoglobin to help store oxygen.  White fibers are often referred to as fast twitch muscles. They are capable of very rapid contraction.  However, these contractions occur in the absence of oxygen.   After a short period of time, a waste product called lactic acid accumulates in the cells, causing the fast twitch muscle fibers to cease contracting.  White fibers are therefore capable of a few very powerful, very strong contractions but tire quickly.

Let’s return to our turkey.  The muscles of the thigh and drumsticks are composed of red muscle fibers.  These muscles are used for walking and scratching the ground.  The muscles do not have to act particularly quickly.  Because they are slow twitch muscles, they do not tend to fatigue.  A turkey can walk around all day without experiencing muscle fatigue.

The flight muscles of the turkey (the breast muscles) are white, fast twitch fibers.  When alarmed, a turkey can use those fast twitch fibers to take off explosively.  However, the flight must be a short one because those white fibers quickly fatigue as lactic acid builds up in the muscles.

In most birds, muscles are not made up of only white fibers or only red fibers.  In turkey breast muscles, there are some red fibers among the many white fibers.  Similarly, the red breast muscles of a pigeon have a few white fibers scattered throughout.  Exceptions to the rule occur in the breast muscles of sparrows and hummingbirds that only have red fibers.

The relative quantity of slow versus fast twitch muscles is related to the particular life style of a bird.  For long distance migrants like tanagers, sandpipers or warblers, their flight muscles must be able to sustain long periods of use.  White fibers would be poorly suited to the task so it comes as no surprise that the breast or flight muscles of these birds are mostly red muscle.

On the other hand, the great power but short duration of white fiber contractions makes white breast muscles suitable for birds that need to take evasive action in flight to avoid predators or to fly through thickly forested habitats.

The size of the breast muscles in a bird is related to its flying ability.  In birds that are powerful fliers, over 20% of the bird’s weight is breast muscle.  In birds that do not fly, less than 10% of the body weight comes from the breast muscles.  The very large breast muscles of domestic turkeys would indicate they are powerful fliers.  However, the size of the domestic turkey’s breast muscles is a result of selective breeding.

The breast muscles of a bird belong to the group of muscles called voluntary or skeletal muscles.  A bird can consciously cause those muscles to contract to allow movement.

The skeletal muscles play another important role in the winter.  When the temperature falls below a critical level, the skeletal muscles begin to shiver.  These rapid, involuntary contractions release heat to help the bird maintain its body temperature.

[Originally published on December 26, 2010]

Recent Ornithological Literature

By in Physiology, Recent Ornithological Literature, Reproduction

In this post, I will review some of the scientific papers recently published in ornithology journals.  All of the articles involve birds that occur in Maine although the research was done elsewhere.

Canada Geese females usually lay between seven and nine eggs.  The young all hatch at the same time, even though females can only lay one egg a day.  One might think that the female would not start to incubate the eggs until the last one is laid so the eggs would develop at the same rate.  Yet, females start to incubate at day three.  How can those eggs laid later possibly catch up?

The mystery was solved by Mark Clark and colleagues as described in a recent Condor article.  They showed that the female adjusts the structure of the egg shell depending on when in the sequence an egg is laid.  Eggs laid later had shells that were more porous and better conductors of heat than shells of early eggs.  The later eggs absorb more heat from the incubating mother and grow more rapidly than the chicks in early eggs.  The result is that all chicks end up ready to hatch together.

Birders know that municipal dumps and landfills are great places to look for gulls.  A large mound of garbage can attract hundreds of Herring Gulls, Ring-billed Gulls, and Great-black Backed Gulls.  Often a few Iceland Gulls and Glaucous Gulls can be present outside of their nesting season. Despite the attraction of gulls for garbage, surprisingly little work has been done to determine if this supplemental food improves gull survival and reproduction.  (Landfills are a different kind of feeding station!).  A recent paper in the Condor by Emily Weiser and Abby Powell examined the importance of garbage on the survival and nesting success of Glaucous Gulls in Alaska.  Their results should be applicable to Maine.

They studied ten Glaucous Gull colonies in Alaska.  Some colonies were within three miles of a landfill, others as far as 45 miles away.  Garbage could be detected in the pellets of 85% of the gulls close to landfills.  Weiser and Powell found a very strong effect of garbage on nesting success.  Gulls who got most of their food from garbage fledged more young.  Although garbage likely allows gull populations to grow, the presence of garbage may benefit the shorebirds and waterfowl that Glaucous Gulls normally feed on by reducing their predation risk.

The Saltmarsh Sparrow reaches its northern nesting limit in southern Maine.  This species is unusual compared to most songbirds because individuals do not form pair bonds and they are not territorial.  The female provides all the parental care to the offspring.

Some observations suggest that Saltmarsh Sparrow nests tend to occur in clusters or “hotspots”.   Some workers claimed that these clusters are associated with particular characteristics of the marsh that provide the best nesting microhabitat.

In a recent Auk article, Trina Bayard and Chris Elphick studied two populations of Saltmarsh Sparrows in two Connecticut salt marshes adjacent to Long Island Sound. Their goal was to rigorously test the claim that Saltmarsh Sparrow nests are clustered.  They sought to find evidence that vegetation differences across the marshes and the presence of other Saltmarsh Sparrow nests might influence nest site selection.

They found 213 nests and documented the characteristics of the vegetation around each nest.  They found that neither the proximity of other nests or vegetation characteristics influenced nest site selection.  In other words, the nests occur randomly in the two marshes.  A careful study put paid to the claim that Saltmarsh Sparrows nest together.

Bicknell’s Thrushes nest in dense fir and red spruce habitat just below tree line in northern New England, the Adirondacks, Quebec and the Maritime Provinces.   The species winters in the Greater Antilles, primarily on Hispaniola.  Because of the low population size and the restricted areas for both nesting and wintering, Bicknell’s Thrushes rank high on species of concern lists.

Little was known about the wintering behavior of this species until a recent article in the Auk by Jason Townsend and colleagues provided important new information.  These authors studied two populations of wintering Bicknell’s Thrushes in the Dominican Republic on Hispaniola, one at a mid-elevation rainforest site and one at a high-elevation cloud-forest site.  The birds at the lower site primarily fed on fruits while the cloud-forest birds fed mostly on insects and other arthropods.  In both cases, the birds maintained solitary territories; a male or a female defended its territory from all comers.  The results suggest that both fruits and arthropods are resources that are worth defending for wintering thrushes.

[Originally published on December 12, 2010]

Effects of Bird Feeders on Birds

By in Physiology

Chances are good that readers of this column maintain a bird feeder.  The U. S. Fish and Wildlife Service estimates nearly a quarter of Americans feed the birds, a practice which has increased greatly in the past 20 years.  We feed the birds to attract these creatures to us for our enjoyment and study.  With all the bird feeders in the United States, it is logical to ask what effect all of these feeders are having on the birds.

One effect of bird feeding is to allow birds to expand their ranges.  Over the past 30 years, several species have expanded their range north into Maine.  These species include Tufted Titmouse, Northern Mockingbird and House Finch.  Mourning Doves have become a lot more common in Maine.  The provision of supplemental food at feeders has been used to explain these range extensions.  Particularly in the winter, few individuals of these species are found far from a feeder.

Another effect of bird feeding is to increase the survivorship of birds.  Members of the chickadee family have been the most-studied species in this regard because they tend to spend their entire lives in a restricted area.  Failure to find a banded bird usually means that bird has died rather than moved to a different area.

The first experimental demonstration of bird feeders improving survivorship was done in Wisconsin by two ornithologists, Margaret Brittingham and Stanley Temple.  Brittingham and Stanley had some sites with sunflower seed feeders and others without.  In each site, Black-capped Chickadees were captured and banded with unique combinations of color bands.  The two workers would regularly census their areas to see which chickadees they could find.  Missing chickadees were presumed to be dead.  Chickadees had higher survivorship in areas where bird feeders were present.  Greater mortality occurred during extended periods of very cold temperature.

Brittingham and Erica Egan repeated this experiment in northwestern Pennsylvania.  In addition to forested sites with and without feeders, these workers also monitored chickadees in suburban areas where there were many feeders.  As in the earlier study, feeders had a substantial effect on winter survival.  In forested areas without feeders, 16% of the chickadees died each month during the winter.  In the forested area with feeders, only 7% of the chickadees died each month.  In suburban areas with many feeders available, only 6% of the chickadees died each month.

We can all attest to the effectiveness of bird feeders in attracting birds to our yards.  People often fret when they are away from their feeders on trips and can’t keep their feeders filled.  Are their local birds in trouble when the feeders become empty?  In other words, do birds become dependent on bird feeders for their food, particularly in the winter?

The answer to these questions appears to be no.  Birds seem to know that they cannot count on even very rich food sources for long periods of time.  Birds will not feed solely from a continuously stocked feeder.  One study has shown that Black-capped Chickadees only take about 25% of their daily food requirements from  well-stocked feeders.  The birds are hedging their bets, looking for other sources of food in case a well-stocked feeder should become empty.

A definitive study to test for feeder dependency in Black-capped Chickadees was done in Wisconsin by Brittingham and Temple.  These scientists studied two large populations of chickadees, banding most of the chickadees so that their survival could be monitored.  For two years, one population was provided with sunflower seeds continuously.  The other population was never given any food.  In the third fall of the study, the feeders were removed from the first study area.  Therefore, during the third winter of the study, neither population had access to supplemental food.  If the chickadees in the first population had become feeder-dependent, we would expect them to have lower survival than the population that never had the benefit of supplemental food.  Brittingham and Temple found that there were no significant differences in winter survivorship.  The monthly winter survival rate was 84%  (with an uncertainty of plus or minus 1%) for the population with feeders in the past and 85% (plus or minus 1%) for the population that never had access to feeders.

Remember that bird feeding is known to improve winter survival of a number of birds so keeping your feeder stocked will maximize this benefit.  However, if your feeder empties while you are away, your local birds will not be at a disadvantage to other birds that never have the benefits of bird feeders.

[First published on November 28, 2010]

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