Highlights of Maine Christmas Bird Counts – I

By in Christmas Count Summaries

The 112th National Audubon Society Christmas Bird Count is now over.  Between December 14, 2011 and January 4, birders picked a day to count as many birds as possible in a circular area, 15 miles in diameter.   These count circles are visited each year, providing a valuable snapshot of changing bird populations over time.

This column is the first of three in which I will describe some of the notable sightings of the 30+ Christmas Bird Counts (hereafter, CBC’s) conducted in Maine this year.

The Christmas Bird Season really offers us a look at bird abundance in early winter; results would likely be different if the counts were conducted in mid-February.

When analyzing Christmas Bird Count results, I find it useful to divide birds into three groups.  The first group includes the resident birds like Black-capped Chickadees and American Crows.  Have there been any changes in their population size compared to previous counts?

Then there are lingering migrants, sometimes called half-hardy species.  Most individuals will spend the winter well to our south but often stick around in Maine until deteriorating weather conditions or the freezing of lakes force them southward.  With the mild fall and mostly open water through December, one might expect a good smattering of lingering birds on this year’s counts.

Finally, there are winter visitors that migrate in some years from more northerly areas to spend a “balmy” winter in Maine.  These birds include Great Gray Owls, Snowy Owls, Bohemian Waxwings, Northern Shrikes and the northern finches like Common Redpolls, Pine Siskins, Pine Grosbeaks, White-winged Crossbills and Red Crossbills.  This year’s counts indicate the current winter is a poor one for these occasional northern visitors.  An exception is the Snowy Owls; these birds have staged an invasion of the northern states (see http://tinyurl.com/6p4gpzz).

The Augusta CBC (December 17) produced a list of 58 species, well above the count average of 46 species.  There was enough open water to hold lingering Common Loons (5), one Great Blue Heron and one American Coot. Six Buffleheads and a Red-breasted Merganser are nice sightings at this time of year for an inland location.

Lingering landbirds included a Northern Flicker, a Ruby-crowned Kinglet, eight American Robins, four Eastern Bluebirds, a Northern Mockingbird,

One Glaucous Gull and five Iceland Gulls were nice winter visitors.

Three Bohemian Waxwings were tallied along with 80 Cedar Waxwings.  Northern Finches were scarce with a single Pine Siskin.

The Lewiston-Auburn Count (December 17) produced a count of 52 species.  Notable aquatic species included four Common Loons, two Horned Grebes, four Bufflehead, 35 Ruddy Ducks and 55 (a new maximum count) American Coots.

A Peregrine Falcon was a nice find.  Five Bald Eagles were the only other raptors found this year.

An impressive list of lingering landbirds was produced.  Counters found a singing (!) Carolina Wren, three Eastern Bluebirds, a Hermit Thrush, 101 American Robin, a Gray Catbird and one Northern Mockingbird.

In what will be a familiar refrain in these summaries, northern finches failed to show.  One Purple Finch, 43 House Finches and 145 American Goldfinches were the only members of the finch family found this year.

The Waterville Count was held the following day and produced a count of 56 species.  Lingering aquatic species included five Common Loons, two Great Blue Herons and two American Coots.  Other half-hardy birds were two Carolina Wrens, two Ruby-crowned Kinglets, 125 American Robins, 11 Eastern Bluebirds, and two Northern Mockingbirds.  A few Song Sparrows are usually found lingering on this count but none were found this year.

For winter visitors, one site in Clinton produced an Iceland Gull, a Glaucous Gull and a Snowy Owl.  A young, light-phase Rough-legged Hawk was a great find.

The northern finches were sparse with 18 Pine Siskins and a lone Common Redpoll counted.

[Originally published on January 8, 2012]

Sixth Edition of the National Geographic Guide to Birds

By in Book Reviews

The battle of the bird field guides is picking up again.  The sixth edition of the National Geographic Society (hereafter, NGS) Field Guide to the Birds of North America has recently been published.  This new edition is much improved.  It will offer some serious competition to other field guides.

When I began birding, the two available field guides were the ones authored by Roger Peterson and by Chan Robbins.  Peterson’s revolutionary arrow system for showing field marks and his fine illustrations were strengths.  However, a separate volume was required for eastern and western birds.  Robbins’ guide covered all the birds in North America in a single guide.  The illustrations were not as good as Peterson’s but it was convenient to have all the birds in one guide.

In 1983, a potent competitor came onto the scene with the publication of the first edition of the NGS Guide.  This guide combined the strengths of the Peterson and Robbins’ guides.  All of the birds of North America, including the rarities, were covered.  Many illustrations were provided for most species, particularly for species like gulls that have a number of different plumages.  The NGS guide displaced the Peterson and Robbins guides in my field pack.

As a cooperative effort, the first NGS guide suffered from uneven quality of the prints.  Some of the bird paintings were excellent and others were mediocre.  But the quantity of information in the NGS guide greatly exceeded the other guides.  The NGS guide has been regularly revised with new illustrations added and taxonomic changes incorporated.

In 2000, David Sibley published the Sibley Guide to Birds, displacing the NSG Guide for me and hundreds of other birders.  Sibley’s superb artistry and his skill in field identification make his guide an amazing resource.  Like the NGS guide, the Sibley Guide covers the rarities as well as the regularly occurring North American birds.

The large size of this guide makes it difficult to carry in the field.  To remedy this disadvantage, the publishers offer a pocketsize version for either eastern or western North America.  This size reduction results in smaller sizes of the illustrations and some loss textual material.  The necessity of having two guides to cover all the North American birds is a drawback.

The Crossley Field Guide published earlier this year is a welcome addition to the field guide universe. This guide is based solely on photographs, arranged as a montage for each species.  The text is terse but informative.  Like the Sibley Guide, the large format of the Crossley Guide makes it awkward to carry into the field.

The most recent NGS Guide, with Jon Dun and Jonathan Alderfer as the head consultants, is an exciting and attractive upgrade from previous editions.  Three hundred new pieces of art are included.  I find no substandard illustrations in this edition.

Navigation is easy.  Both the front and back covers are folded.  Unfolding the front cover provides a visual index of all the birds except for the passerines (perching birds) with the appropriate page to visit.  The unfolded back cover has a similar visual index for the passerines.  A Quick Find Index of about 160 common names like crane, crow or swift is useful.  Finally, there are seven recessed, labeled thumbholes that allow you to instantly get to the sections for Hawks, Sandpipers, Gulls, Flycatchers, Warblers, Sparrows and Finches.  Very useful!

The species coverage is exhaustive.  This edition provides an illustration and some text on 92 accidental species that have been recorded in North America three times or fewer.  Altogether, 990 species are covered.

One more innovation is the inclusion of maps of subspecies for 37 bird species.  This information will be of interest to bird listers because some of these subspecies will likely be elevated to full species.

In the final analysis, I am impressed with the sixth edition.  I now keep a copy in my field pack.

[Originally published on December 25, 2011]

Flocking

By in Behavior, Species Accounts

I have had lots of inquiries this fall about the lack of birds at bird feeders.  I don’t think Hurricane Irene or other natural phenomena have caused bird populations to plummet.  Rather, I think that our resident birds are finding enough food in nature during our mild and mostly snow-free fall so far.  I have hopes that we will get a nice influx of Common Redpolls and Pine Siskins this winter throughout our state.

An obvious difference in birds from breeding season to the winter is the increase in flocking behavior. During the breeding season, a pair of birds often occupies a nesting territory for the exclusive use of themselves and their young.  This territorial behavior breaks down after the nesting season and flocking behavior is commonly observed in the fall, persisting until the following spring.

What is the advantage of flocking?  Ornithological research has indicated two major advantages of this social behavior.  The first is an increase in foraging success, that is an increase in the success of finding food.  Food abundance for many birds is typically much reduced in the winter in comparison to the bounty of summer.  Furthermore, food in the winter tends to be patchy.  The food, such as acorns or birch seeds, may be abundant in one small area but non-existent in nearby areas.

In such cases where food is rare and patchy, flocking can be a real advantage to birds in locating the highly dispersed food.  With many eyes searching for food, it is likely that a food bonanza will be located that might well be missed if only one or two birds were searching the same area.

Even though the food will need to be shared among a number of birds, a modest meal is better than no meal.  Sometimes, it pays to cooperate.

The second advantage of flocking is an increase in the detection of predators.  With many pairs of eyes searching for Sharp-shinned Hawks or Northern Shrikes, flocking land birds stand a better chance of seeing those predators.  Watch the American Goldfinches, Black-capped Chickadees and other birds at your feeder.  You can see each bird spends a good bit of time looking around, ever vigilant against predators.

Both of these advantages of flocking may be realized for a flock.  Actually, there may be an interaction between these two benefits.  With lots of birds keeping a watch out for predators, each individual in a large flock devotes less time to searching for predators and more time in searching for food.  An individual bird would have to spend much more time being vigilant and therefore have less time to forage.

A flock, like many human families, is not free of conflict.  Often times within a flock, one can observe a pecking order or hierarchy in the flock.  One bird is dominant to all in the flock; the second bird in the pecking order dominates all but the top bird and so on down to the most subordinate bird that dominates no member of the flock.

Birds rarely have to resort to fighting to claim their position in a pecking order.  A dominant bird may simply make a threatening gesture and the subordinate bird will make a submissive gesture.  As an example, the Jackdaw (a Eurasian member of the crow family) shows submission by bending its head low and turning the nape of its neck toward the dominant bird.

Black-capped Chickadees provide a nice local example.  In a winter flock, the dominant bird is the single adult male in the flock and its mate is the second-highest ranked individual.  The remaining flock members are juvenile birds, none of which are the offspring of the adult pair.  These juveniles interact with each other during the fall to establish a strict pecking order.

[First published on December 11, 2011]

eBird Animations; Review of The Atlas of Birds

By in Book Reviews, Software

eBird

In a previous column, I sang the praises of eBird, the website maintained by the Cornell Laboratory of Ornithology and National Audubon Society.  This site serves as the depository for bird sightings from birders and ornithologists throughout North America and beyond.

Today, I want to point out one great resource that the eBird programmers have made available to take advantage of the many records in the database.  You can now see occurrence maps for a number of migratory birds in the United States.  The maps were created by relating the records of a particular species with 60 variables describing aspects of habitat, climate, and human population size throughout the U.S..  This model predicts the weekly occurrence of a species of interest as an animated map.  It’s really cool!  Check out the website at http://ebird.org/content/ebird/about/occurrence-maps/

At this point, the animations only cover the lower 48 states.  If you click on Lapland Longspur, you will see they move out of the United States during April.  That’s because they are migrating to their breeding grounds on the Canadian and Alaskan tundra.  They reappear in the lower 48 in September.  Similarly, neotropical migrants like the Scarlet Tanager appear on the animation in early April and are mostly gone by the first of October.  During the non-breeding season, most Scarlet Tanagers are in Bolivia, Perú or Ecuador.  I expect that in the future, the occurrence maps will include all of the western hemisphere.

The Atlas of Birds

Princeton University Press has recently released the Atlas of Birds: Diversity, Behavior and Conservation by Mike Unwin.  The book is an overview of many different facets of the biology of birds.  The book is 144 pages long in a large format (8.5 by 11 inches).  The text is richly illustrated with color photographs and color maps.

The book is divided into seven units.  Introduction to Birds provides information on the fossil history of birds and the relationship of birds to the dinosaurs.  Brief coverage of feathers, a hallmark of birds, is provided.  Next is a section on Where Birds Live, focused on the birds of major geographic areas like Africa or Australasia.  The author briefly covers Important Bird Areas, sites identified by BirdLife International that provide vital habitat and resources for birds and hence have high conservation value.

The third section, Birds in Orders, is an efficient catalog of the major groups of birds, from the ratites (ostriches and relatives) to the perching birds.  A section on How Birds Live covers reproduction, foraging, coloniality and migration.

The fifth section is called Birds and People.  Here the author describes the importance of birds in human diets, in human culture and in simply providing human  pleasure.

Birds under Threat discusses extinction and some of the reasons for bird declines (loss of habitat, pollution, introduced species, climate change).  The final section, Protecting Birds, focuses on the efforts of BirdLife International, an umbrella group of non-government conservation organizations around the world.  The author gives some detail on the efforts to reduce albatross and other seabird deaths.  Many of these birds drown from getting hooked on long lines or getting trapped in trawling nets.   By using modified fishing gear and using bird-scaring devices to keep birds away from nets and lines, many seabird lives have been spared.

I found this book to be delightful.  The text in the book is limited so the coverage of any particular topic cannot be thorough.  Nevertheless, the author conveys a tremendous amount of interesting facts with a remarkable economy of words.

The book is laid out in facing page units so you can start reading anywhere.  It’s like eating at a smorgasbord.  No particular dish will be enough to fill you up but by the end of sampling all the dishes, you have a satisfying meal.

[First published on November 27, 2011]

Big Year; Boreal Forest Conservation

By in Bird Conservation, Book Reviews

Big Year

Perhaps you saw the movie The Big Year earlier this fall.  Starring Steve Martin, Jack Black and Owen Wilson, this movie is adapted from a book by Mark Obmascik of the same name.  The book describes the efforts of three birders to see as many species as possible in North America in a single calendar year.

The current record for a North American Big Year is a whopping 745 species!  To amass that total requires a birder to find all of the 660 or so species of birds that occur predictably every year in North America.  Then, the birder has to chase as many vagrant species as possible.

A big year on this scale requires the time and the money to embark on sudden trips to south Florida to see the vagrant LaSagra’s Flycatcher or to southeastern Arizona for the rare Aztec Thrush or to south Texas for the unexpected Green-breasted Mango.

The good will and cooperation of other birders is key to a successful Big Year.  Most of the rarities a Big Year birder sees will not found by him or her.

John Vanderpoel of Colorado is in the midst of an amazing Big Year.  He has already seen 729 species as of this writing.  He has a good chance to eclipse the old record of 745 species.

John is maintaining a blog to document his trips and to share photographs of the many birds and other animals he has seen.  He also provides a list of birds he has seen and ones he is hoping for.

In looking over his list, he has a couple of regularly occurring species that should be easy to pick up (Eurasian Tree Sparrow and Gray Partridge).  He has not seen Brown Jays or Tamaulipas Crows in south Texas yet.

He is planning to go on a pelagic bird trip in the Gulf of Maine on November 12, hoping to add a Great Skua to his list. He will no doubt chase a Pink-footed Goose in Nova Scotia that has been present for a couple of weeks.  A Barnacle Goose was present in Aroostook County in late October but has not been relocated since the snow storm.  Perhaps it will reappear, becoming a chase bird for Vanderpoel.

After John’s New England and Nova Scotia trip, he will be standing by to go for rarities wherever they might appear.  South Florida, Texas and Arizona are the most likely places for rare species but with birds, you never know.  One of John’s rarest birds was a Gray-hooded Gull that appeared at Coney Island!

I encourage you to visit John’s blog at http://www.bigyear2011.com/ and check his progress.  It’s fun to vicariously experience his Big Year.

Boreal  Forests

The huge boreal coniferous forest that covers much of Canada and the northern tier of the United States has great ecological significance.  For birds, this forest provides breeding habitat for millions of migratory birds of several hundred species.   Other birds like Spruce Grouse, Black-backed Woodpeckers, Boreal Chickadees and Gray Jays spend their entire lives in the boreal forest.

Alas, the boreal forest is not immune to the depredations of humans.  Industrial development and climate change are obvious threats.  The damming of waterways for hydropower has flooded some habitats.  Strip-mining and the extraction of oil from tar sands have had profound impacts on both land and water quality.  Climate change is leading to melting of the permafrost and the drying up of wetlands.

A joint report, entitled Birds at Risk, has recently been released as a joint effort from Nature Canada, the Boreal Songbird Initiative and the Natural Resources Defense Council.  You can download a copy at http://www.borealbirds.org/resources/Report-BirdsAtRisk.pdf

The report documents the threats to the boreal forest and suggests bold policy steps that governments must take to protect the boreal forests.

[First published on November 13, 2011]

eBird

By in Software, Uncategorized

With the passing of Steve Jobs earlier this month, we have all been thinking about the way that computers and the internet have transformed our lives.  The information highway has had profound effects on the ease and speed with which birders can communicate.

Nowadays, a birder can find a rare bird, send a post to a birding listserv on her smartphone and within minutes hundreds of people know about that rare shorebird in Scarborough Marsh.  Amazing!

One of the potential problems of so much information on the web is that it is often diffuse.  It may take quite a bit of browsing to find the information one seeks.

The National Audubon Society has a great site where one can get access to all the 100+ years of Christmas Bird Count data (http://birds.audubon.org/christmas-bird-count).  Similarly, the Breeding Bird Survey, jointly administered by the U. S. Geological Survey and Canada’s Canadian Wildlife Service, makes their data available as maps or raw data (http://137.227.245.162/BBS/index.html).

These two sites are limited to particular census programs.  Is there a site where any bird observation can be posted and shared?  Yes, there is a site called eBird, administered by the Cornell Laboratory of Ornithology and the National Audubon Society.  eBird was begun in 2002.  It is essentially an on-line checklist project.  Over 200,000 birders and ornithologist are currently submitting their trip lists to eBird.  All of the data go into a common database that can be searched by anyone.  The sharing of data makes eBird a tremendous resource for birders planning a trip or for scientists looking to determine how various phenomena affect birds.

eBird version 3 has recently been introduced.  This version is a great improvement over the previous versions.  eBird 3 is intuitive, clean and simply a joy to use.

Here’s how one goes about contributing bird data to eBird.  I do a lot of birding in the Perkins Arboretum on the Colby College campus.  For the first checklist I added, eBird asked me for the date, the hours of observation and the location of the site.  To identifiy the location, you can add the latitude and longitude or you can find it on a map.  Clicking on the “find on a map” took me to Google Maps in an embedded window.  I quickly found the arboretum and named my location “Perkins Arboretum – Colby College”.  That location now shows up in “my locations” on eBird.  When I add new checklists for the arboretum, all I have to do is indicate the location by name and eBird fills in the details.

Next eBird presents you with a checklist of birds for the area.  So, you will see a different list for a Maine location compared to an Arizona or Galápagos location.  You can just scroll down through the checklist and either check-off or give the actual number of birds seen on a trip.  Punch submit and the checklist is part of the eBird database.

Every eBird registrant has a “My eBird” page.  eBird goes through all of your sightings and prepares lists of your birds.  You can see your life list, year list, month list as well as lists by region of the world, country, state and even county.    You can sign up for an email alert (daily or hourly) that will send you reports of, for instance, birds in Maine that you have not seen.

 

Even if don’t submit your checklists, you can use eBird to learn of recent sightings.  Just set up a page at igoogle.com.  Click on the Add Gadgets link and search for eBird.  At least three different gadgets are available for download, each customizable to a particular state.  Everytime you visit your iGoogle page, you will see a listing of unusual birds with a link to a map of the sighting.

[First published on October 20, 2011]

Reverse Migration

By in Migration

The past couple of weeks have been exciting ones for the fall landbird migration.  In today’s column, I will describe a recent field trip to make a couple of points about the nature of the autumnal migration.

October 3 was a rainy, windy day.  Realizing the promise of productive coastal birding, Luke Seitz, one of the top birders in the state, decided to check out coastal sites in southern Maine.  What a day he had!   Along with the more expected warblers and sparrows, here are exceptional sightings made by Luke at Cape Neddick and Fort Foster:  11 Yellow-billed Cuckoos, seven White-eyed Vireos, one Yellow-throated Vireos, a Worm-eating Warbler, two Blue-winged Warblers, four Hooded Warblers, two Connecticut Warblers, one Yellow-breasted Chat, a Summer Tanager and a Blue Grosbeak.  You can see some of Luke’s photographs of these birds at 6jvjm5h

The phenomenon that Luke experienced is called a fallout.  Inclement weather forces migrating birds to abort their evening’s journey and seek shelter.  It’s likely that many of these birds were flying westward off the shore to find cover.  Of course, Luke knew that the weather conditions were favorable for a coastal fallout of migrants and his hunch was proven correct.  So, windy, rainy days can often be the best times to go birding in the fall.

So why were the birds listed above exceptional sightings for Maine?  Yellow-billed Cuckoos are uncommon nesting birds in southern Maine so seeing 11 in one day is remarkable.  Yellow-throated Vireos and Yellow-breasted Chats are uncommon breeders in southern Maine.  Both of these species are much more abundant south of Maine, all the way down to Florida on the eastern Seaboard.  Blue-winged Warblers are uncommon breeders in southern Maine and are most common in the mid-Atlantic states to the mid-West.

The remaining species do not nest in Maine.   The northern limit of the breeding range is southern New England for White-eyed Vireos and Worm-eating Warblers.  Hooded Warblers reach southeastern New York and New Jersey.  Summer Tanagers and Blue Grosbeaks reach their northern breeding limits in southern Pennsylvania.

Furthermore, all of these species winter south of North America.  Most migrate to Caribbean Islands or Central America for the winter.  Some Summer Tanagers go all the way to South America.

What in the world are these migrants doing in Maine in October?  Shouldn’t they be well on their way south to tropical areas?

The explanation is a phenomenon that ornithologists call reverse migration (or reverse orientation).  Young geese, swans and other large birds migrate in flocks.  Young birds can learn the migratory route from experienced older birds that have made the trip before.

However, perching birds do not migrate in cohesive flocks.  These birds have their migratory route genetically programmed.  In most cases, a juvenile bird is able to find its way to a wintering area where it has never been.  A neat trick!

In some cases, however, birds become disoriented by 180 degrees and hence embark on a north-bound trip in the fall when they should be heading south.  Most birds that undertake these reverse migrations are inexperienced, juvenile birds.  So for those of us in northern areas, reverse migration in the fall affords us the best chance to see migratory perching birds that are normally found well to our south.

Some extralimital birds seen in Maine may have arrived here by an orientation error different from a 180 degree angle.  For instance, a Smith’s Longspur (the second record for Maine) was found in Norridgewock in late September.  Smith’s Longspurs breed in the arctic tundra of Alaska and Canada and winter in Oklahoma and adjacent states.  The Norridgewock bird had to have taken a southern migration route about 45 degrees to the southeast of its proper route to find itself in Maine.

[Originally published on October 16, 2011]

Nocturnal Migration

By in Migration

The fall landbird migration is peaking now.  Most warblers have already passed south.  Thrushes and sparrows will dominate the October migration.

The fall migration is more leisurely than the spring migration for most birds.  There is an urgency about the spring migration as birds are driven to arrive on the breeding grounds as early as possible to stake out good territories and find a mate.

In some ways, the fall migration is even more impressive.  This migration involves the spring migrants that survived the breeding season as well as all the young born in the summer.  Ornithologists estimate that five billion birds migrate in North America alone each fall!

Some species of birds migrate during the day.  These include pelicans, hawks, falcons, hummingbirds, swifts, and swallows.  All of these birds are strong fliers.  The larger birds can take advantage of thermals that develop during the day.  Swifts and swallows can feed on the wing during the day as they migrate.

The majority of land birds migrate at night.  These include cuckoos, flycatchers, warblers, vireos, thrushes, orioles and sparrows.  Most of these birds are denizens of woods and other sheltered habitat.  These birds are not extremely agile fliers so need dense habitat to avoid bird predators.

Migration at night has at least three advantages.  Birds do not have to worry about falcon or hawk attacks.  Second, the air in the atmosphere is usually less turbulent than during the day.  Lastly, the air is cooler at night.  A migrating bird produces a huge amount of excess heat that needs to be released.  Most of the heat is lost from the unfeathered legs.  The colder the air temperature, the more quickly that heat can be dumped.

Migrating birds wait for favorable winds before starting a migratory leg.  Keep in mind that high pressure systems rotate in a clockwise fashion and lows are counterclockwise.  So, the leading edge of a high or the trailing edge of a low have the southerly winds that favor a strong migratory flight that night.

The evidence of a strong migration can be a fallout of many birds the following morning.  But there are more direct ways to experience nocturnal migration.

First, you can set up a spotting scope or use your binoculars and watch the face of the moon.  It’s very cool to watch migrating birds wing across the lighted surface.   Most nocturnal migrants start shortly after dusk and peak around midnight.

Migrating birds can also be seen on radar.  In the early days of radar, echoes of many, small targets were seen but poorly understood.  These echoes were called “angels”.  Now, we know that the angels are actually birds and sometimes bats.

Radar is now used as a powerful tool to study nocturnal migration.  Sid Gauthreaux of Clemson University is one of the pioneers of this field. Check out the radar image showing many angels at his website: http://virtual.clemson.edu/groups/birdrad/COM4A.HTM

Yet one more way to appreciate nocturnal migration is to use your ears.  Nocturnal migrants are noisy, regularly emitting short flight notes.  In some cases, the flight notes are similar to the calls the birds give while they are on the ground.  In many cases, however, the flight notes are only given during a nocturnal flight.

Bill Evans has been a pioneer in the study of nocturnal flight calls.  Visit his website at  http://www.oldbird.org/

On his website, Evans has sonagrams for a number of warblers and sparrows.  He also sells a CD with recordings of the nocturnal flight calls of 211 species. It’s a good investment.

On a night that is not too windy, you can hear the flight notes above.  However, a microphone will capture many more of those vocalizations.  Evans provides directions on how to build a microphone system using cheap materials like a plastic flowerpot, saran wrap, a dinner plate and an inexpensive microphone.

[Originally published on October 2, 2011]

European Starlings

By in Species Accounts

I have European Starlings on my mind.  I have been watching some of the large flocks (called murmurations) of starlings wheeling throught the air around dusk as they prepare to go to roost for the night.  I’m sure you have seen this behavior too.  The flocks form in the fall after the breeding season and will persist until next spring.

A flock in flight seems to have a collective mind of its own as the birds change direction often in unison.  It is remarkable that birds don’t fly into each other as they perform their aerobatic maneuvers.  Thanks to the work of two Italian ornithologists, Dr. Michele Ballerini and Dr. Andrea Cavagna, we have a better understanding of the synchronized flight of these murmurations.

Ballerini and Cavagna used a series of interlinked cameras to record murmurations in flight.  A computer assimilated the data from the cameras to produce a three-dimensional map of all the birds in the flock.

The researchers easily disproved the notion that there is a leader in the flock.  Rather, birds seem to follow a couple of rules: fly in the same direction as your neighbors and keep your neighbors by your side rather than in front or behind.  Like most birds with eyes set on the side of the head, starlings have a blind spot behind the head and directly in front as well.  The best vision is off to the side.  We know that starlings can change their direction in 100 milliseconds!

The videotapes clearly showed that the spacing of the birds in the murmuration is not uniform.  Birds in the middle of the flock are spaced closer together.  Furthermore, birds change their position in the flock, sometimes on the outside and sometimes moving in.

Flying together seems to confer protection from aerial predators like falcons or accipiters, much like small marine fish flock as protection against barracudas.  The idea is that the many individuals are confusing to the predator.

Woe unto the bird or fish that turns right when all the others turn left in the presence of a predator.  It becomes easy pickings for the predator.  So, the safest portion of a flying murmuration is in the middle.  It’s not surprising that there is a tendency of birds on the edge to flying toward the center.  This movement has been termed selfish flock behavior

These aerial ballets have only been performed in North America for the past 120 years or so.  European Starlings are an introuduced species in the western hemisphere.   Their presence here is due to a man named Eugene Schieffelin. Schieffelin was a rather prosperous Englishman who moved to New York City around 1880.  He thought it would be wonderful if Central Park had populations of all the birds mentioned in Shakespeare’s plays.  The first species he tried to introduce was the European Starling.  He introduced around 100 birds in 1890 and 1891.  His introduction was far more successful than he could ever have imagined.  From those 100 birds, a population of more than 200 million birds now stretches across the continent.

The introduction of starlings has had negative impacts on our native birds.  A starlings all-purpose bill allows it to take a wide variety of food (seeds, fruit, invertebrates) .  Starlings can compete for food with many types of birds.

In addition,  tarlings are cavity-nesters and their aggressive battles for nesting cavities has negatively affected native cavity-nesters.  Eastern Bluebirds, Tree Swallows and woodpeckers are birds, which clearly have declined as starlings increased.  Competition for cavities by starlings has affected other cavity-nesters as well like Tufted Titmice and nuthatches.  Providing nestboxes with diameters too small for starlings to enter can ameliorate the problem.

[Originally published on September 18, 2011]

Wilson’s Storm-Petrel

By in Species Accounts, Uncategorized

Did you know that possibly the most abundant bird in the world is in Maine now?  And that the vast majority of Mainers have never seen one?  The bird is Wilson’s Storm-Petrel, a small seabird that is regularly seen from whale watches and fishing expeditions.  Occasionally these birds may be seen from shore when onshore winds push them landward.

Wilson’s Storm-Petrels belong to the order of birds called the tubenoses.  This order includes three families: the  large albatrosses, shearwaters and gadfly petrels, and the storm-petrels.  The cylindrical external nostrils on the bill give these birds their order name.  Spending most of their lives at sea with no ready source of freshwater, tube-noses have special glands in the nose that secrete salt .  The salt is dribbled out through the tubes onto the surface of the bill.

Wilson’s Storm-Petrels do not breed in the northern hemisphere.  Rather, they are now spending their winter on the offshore waters of the western Atlantic.  These birds are small, about the size of a swallow (seven inches in length).   They may be identified by the short, squared tail and the the relatively long legs that cause the feet to extend beyond the tip of the tail  They have yellowish-green webbing between the toes (good luck seeing that field mark from a bouncing boat!).  Perhaps the best identification feature is the broad, U-shaped white band on the rump that extends underneath to the undertail coverts; the white rump is easily seen against the rest of the brown feathers on the body.  From above, these birds have a pale bar on the upper surface of the wings.

Wilson’s Storm-Petrels fly close to water surface with purposeful, shallow wing beats similar to those of a swallow or small tern.  Flight is direct with steady shallow wing beats.

Like most storm-petrels, Wilson’s Storm-Petrels feed on the small, drifting organsims called plankton.  These include larval fish, various crustaceans including krill, and jellyfish.

Most storm-petrels, including Wilson’s, use a fascinating pattering behavior to help them feed.  A storm-petrel will hover over the sea and dip its feet into the surface of the ocean three of four times.  This dipping seems to attract larval fish and crustaceans, which then become lunch for the storm-petrel.

Some authors have described this pattering as walking on the water.  In fact the name petrel is an allusion to the biblical account of St. Peter walking on the water.  The storm part of the name comes from the observation that these birds are generally seen by landlubbers only after major storms.

In the Caribbean, Wilson’s Storm-Petrels are called skipjacks.  Newfoundland fishermen call them Mother Carey’s Chickens, a corruption of Mater Cara (Dear Mother), a reference to the Virgin Mary.

Like other tubenoses, Wilson’s Storm-Petrels have a good sense of smell.  It’s great fun on a pelagic bird trip when the captain spreads a little cod liver oil on the surface of the ocean.  Within a short while, tube-noses of various sorts find their way to the slick.

Wilson’s Storm-Petrels will follow fishing boats, attracted no doubt by the fishy odors emanating from the boat.   It’s not unusual to see 50 or more around a boat.

In their breeding season (our winter), Wilson’s Storm-Petrels breed near high-density plankton areas around the ice in far south and turbulent seas in the subantartic zone off South America.  They seem to breed on virtually every suitable exposed rocky area off the coast of Antarctica as well.

A single egg is laid in a burrow and both members of the pair incubate and feed the chick once it has hatched.  It takes 40-50 days for the egg to hatch.

Descriptions of their numbers in the southern seas are mind-boggling.  Some observers have observed acres of Wilson’s Storm-Petrels off the coast of South Georgia so dense that the birds seem to be touching each other.  Flocks of thousands or tens of thousands of bird are often reported.

Audubon mentioned Wilson’s Storm-Petrels as breeding on islands off Nova Scotia and other writers extended this claim to include Maine.  The error persisted for many years until finally corrected by Brewster in 1884.  Audubon was undoubtedly observing Leach’s Storm-Petrel, a similar species that nests from Maine northward.  These birds tend to forage at night so are rarely seen during the day.

After the brief breeding season in the subantarctic waters, Wilson’s Storm-Petrels make their way north to more equitable climates to spend most of the year.  They arrive in the Gulf of Maine by early June and mostly depart by the middle of September.

[Originally published on September 4, 2011]

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