Recent Ornithological Literature

By in Recent Ornithological Literature, Reproduction

In this column, I will provide a synopsis of several scientific papers that recently appeared in ornithological journals.  All of the papers deal with birds that occur regularly in Maine and some of the research was performed in our state.

The practice of laying eggs in the nests of other species of birds is a hallmark of the Brown-headed Cowbird.  This sneaky trick, called brood parasitism, poses a huge conservation threat to many species of eastern birds.  These cowbirds have only been in the east for less than two centuries.  Prior to the European colonization of North America, Brown-headed Cowbirds were found on the western plains, following bison to feed on the insects the bison displaced while grazing.

With the conversion of eastern forests to pasture land, habitat was created that allowed cowbirds to spread east.  The various species of birds that are hosts to the cowbirds’ eggs and nestlings had no prior experience with cowbird brood parasitism and in many cases have not had time to adapt.

Mélanie Guigueno and Spencer Sealy published a recent article in the Condor that examines the behavior of Yellow Warblers whose nests contain one or more Brown-headed Cowbird eggs.

For species that are able to distinguish a cowbird egg from their own eggs, several behaviors are available to thwart the efforts of the cowbird to pawn off the rearing of her own young.  Sometimes, a host grasps the cowbird egg in its bill and ejects the egg from the nests.  This efficient method requires a fairly large bill (15 millimeters long). Unfortunately, the Yellow Warbler’s bill is too short.  Some hosts will puncture a cowbird egg, pick it up with its bill and eject the egg over the side of the nest.  Yellow Warblers cannot do puncture-ejection of the eggs.

However, Yellow Warblers do have a unique way of fighting back against cowbird brood parasitism.   They construct part of a new nest (embedded burial) or an entirely new one (true burial) over the parasitized clutch of eggs and start the egg-laying process over again.  Sometimes, the pair of Yellow Warblers will simply desert a parasitized nest and seek a new nesting site.

The authors studied 132 nests over 13 years. They found that burial of parasitized clutches occurred about two-thirds of the time and desertion was the strategy in the other cases.

We are fortunate in Maine to have two breeding species of sparrows that frequent salt marshes: Nelson’s Sparrow and Saltmarsh Sparrow.  Both were formerly united as a single species, the Sharp-tailed Sparrow.  Saltmarsh Sparrow has a more southerly distribution, breeding as far south as Virginia.  Nelson’s Sparrow along the Atlantic coast breeds from New Hampshire northward.  In places like Scarborough Marsh, both species can be found in the same marsh, sometimes hybridizing.

Chris Hill and colleagues recently published an article in the Auk on Saltmarsh Sparrows.  This species has an unusual life history compared to other sparrows.  Males do not maintain a territory and do not form pair bonds with females.  The males are deadbeat dads; they do not participate in the rearing of the young.

Using DNA comparisons, the researchers found that multiple partners were typical for female Saltmarsh Sparrows.  Fifty-seven of 60 broods with at least two chicks resulted from females having two or more male partners.  About a third of the broods had a different father for each chick.  The most common result though was for one male to have fathered two or more but not all the chicks in a nest.

The males moved around in the salt marsh, siring chicks in nests up to a mile apart.  The life history of this species is really quite different from the strongly territorial reproduction of related species like Song Sparrows.

A team of researchers including Maine ornithologists Tom Hodgman and Peter Vickery published a comparison of home range sizes and habitat use by Nelson’s Sparrow and Saltmarsh Sparrows in the Wilson Journal of Ornithology.  This work was done in Scarborough Marsh.

The researchers used radio-transmitters to track the movements of 63 Nelson’s and 77 Saltmarsh sparrows.  Like the Saltmarsh Sparrow, Nelson’s Sparrows do not defend a breeding territory.  However, they do tend to spend most of their time in particular areas, overlapping with individuals of both species.  Theses areas are called home ranges rather than territories.

Using the location data from the radiotransmitters, the researchers found that the home range of male Nelson’s Sparrows was over twice as large as that of male Saltmarsh Sparrows (a whopping 300 acres compared to a still impressive 125 acres).  Females of both species had similar home ranges of 70 to 100 acres.

[Originally published on July 4, 2010]

Nesting Associations

By in Uncategorized

The reproductive success of birds depends in large part on the location of the nest.  A nest should provide protection from the elements.  It should be well hidden to prevent its discovery by egg or nestling predators.

Some bird species build their nests in the proximity of other species of birds. In today’s column, we will explore some of these nesting associations and learn the advantages of such arrangements.

This column was inspired by an observation that Bets Brown (my wife) and made on June 16.  Bets was conducting a Breeding Bird Survey and I came along as her data recorder.  At a stop in Monmouth, a pair of Ospreys had constructed a nest atop an electrical transformer tower.  Bets saw a couple of small birds disappearing into and emerging from the bottom of the massive nest.  Those birds were House Sparrows.  What better place to place a nest?  Potential predators of House Sparrow eggs or nestlings are likely to be deterred by the fearsome Ospreys.  As strict fish-eaters, Ospreys pose little threat to the House Sparrows.

A search of the literature revealed that House Sparrows have been reported nesting in Osprey nests in other areas.  Monk Parakeets, which build spherical stick nests, have also been seen using Osprey nests as a site for their own nest construction.

Although the pair of House Sparrows we saw likely benefitted from the association with Ospreys, we do not know if the House Sparrows particularly sought out the Ospreys or simply found the massive nests of the Ospreys to be a nice place to set up house.  I suspect it was the latter.  In any case, House Sparrows outnumber Ospreys by many orders of magnitude so a House Sparrow nest in an Osprey nest must be an exceptional event from the point of view of House Sparrows.

However, nearly 100 bird species clearly prefer to nest in proximity to a more aggressive species.  Most examples of protected associates are waterfowl, shorebirds and songbirds while the aggressive species sought out by the protected associate species are usually particularly aggressive shorebirds, falcons and sometimes stinging or biting insects.

In Ontario, Yellow Warblers prefer to nest close to Gray Catbird or Red-winged Blackbird nests.  Near Gray Catbirds, predation on the warbler nests is significantly reduced.   Brood parasitism by Brown-headed Cowbirds is greatly reduced in warbler nests near Red-winged Blackbird nests.  The redwings aggressively keep cowbird females out of their territories.

On Kent Island in the Bay of Fundy, Savannah Sparrows have two major nest predators: abundant but ineffective Herring Gulls and uncommon but ruthlessly effective American Crows.  The sparrows choose to nest near the gulls because the gulls keep the crows away.  The sparrows build their nests in dense microhabitats that the gulls avoid.

In the Siberian arctic, more than 80% of Red-breasted Geese nest close to either Peregrine Falcon or Snowy Owl nests.  Arctic Foxes are a major threat to goose eggs and goslings.  In 454 hours of observations, no nest predation by foxes was observed for nests in the vicinity of owls or falcons.  In fact, foxes only came within the defense area of the aggressive species twice and in both cases were quickly attacked.  The foxes fled with their tails literally between their legs.

In the Manitoba arctic, Long-tailed Ducks choose to nest near Arctic Tern nests.  In some habitats, the ducks place their nests within three meters of the aggressive terns.

We know at least one example where a protected associate has a negative influence on the aggressive species.  In Peru, Black Skimmers and two species of terns nest on beaches along the Manu River.  The terns and skimmers actively defend their nests against predators.  Sand-colored Nighthawks nest among the skimmers and terns, often in numbers exceeding the aggressive species.  The nighthawks never defend their nests, relying instead on the protection of the skimmers and terns.  The nighthawks had greater nesting success in association with the other birds.  However, their presence reduced the success of the terns and the skimmers because they spent more time in defense and less in parental care.  The nighthawks are essentially parasitizing the terns and skimmers.

Purple Finch project

Sarah Knutie, a graduate student at the University of Utah, is beginning a long-term monitoring project of Purple Finches.  She is soliciting volunteers who are willing to keep track of Purple Finch, House Finch and Pine Siskin abundance at their feeders from September through March.  The time commitment is modest, only 1-2 hours a month.  If you would like to help Sarah with her project, let her know of your interest by emailing her at [email protected]

[Originally published on June 26, 2010]

Maine Landscapes and Odonates of Massachusetts

By in Book Reviews, Odonates, Plant Communities, Uncategorized

Maine Landscapes

The Maine Natural Areas Program has recently published a book by Susan Gawler and Andrew Cutko entitled Natural Landscapes of Maine: A Guide to Natural Communities and Ecosystems.  Gawler and Cutko describe 104 natural communities in Maine, based primarily on the distribution and abundance of woody plants.  This book will be of interest to any naturalist in Maine, not just to botanists.

Some of the community types like Beech-Birch-Maple Forest, Hemlock Forest or Spruce-Northern Hardwoods Forest cover vast tracts of Maine.  Others like Atlantic Cedar Bog or Pocket Swamp or Jack Pine Woodland are much smaller in areal extent.  However, each community type is given equal treatment in a standardized format.  Two pages are devoted to each community.  Several photographs of the habitat or particular characteristic species are provided along with a map showing the occurrence of the community type in Maine.  A list of the characteristic plant species is provided along with a list of any rare plants found there.  Each account has a list of sites with public access so interested people can visit an example of that community type.

Each account also lists particular bird, butterfly, moth, dragonfly, and other animal species that occur in each community type.  The inclusion of this information makes the book a valuable resource for any birder looking for birds with restricted distributions in the state.  As examples, Red Maple Swamps provide good habitat for Louisiana Waterthrushes and Yellow-throated Vireos and Spruce-Fir Krummholz is the place to go for Bicknell’s Thrushes, Blackpoll Warblers and Spruce Grouse.

Dr. Mac Hunter, a faculty member in the Department of Wildlife Ecology at the University of Maine, provides an insightful foreword to the volume.  He writes about the value of natural community classifications as a tool for conservationists.  We can protect many species by preserving a particularly nice tract, for example, of Maritime Spruce-Fir Forest.  We know that all the many species found there will be protected.  This habitat-scale means of conservation is called a coarse-filter approach.  Of course, some species may need a fine-filter approach, conservation practices developed for the particular needs of a threatened species.    Protecting lakes would not eliminate the threat of mercury and organic contaminants for Common Loons on those lakes so a fine-filter approach is needed there.  For the coarse-filter approach, the landscape classifications developed by Gawler and Cutko are essential.

Serving in many respects as a field guide to the habitats of Maine, this book is worth owning by any Maine naturalist.  In addition, the book is a celebration of the amazing biodiversity of the state.  I enjoy picking up the book and just sampling a few of the landscape types.  We live in a state of great natural riches.

You can obtain a copy by contacting the Maine Natural Areas Program, Maine Department of Conservation, 93 State House Station, Augusta, ME 04333-0093 or you can download an order form at: http://www.maine.gov/doc/nrimc/mnap/publications/community_classification.htm

The cost of the book is $20 including shipping (cash or checks only).

Dragonflies

A bird in flight is amazing in its grace and power.  But have you ever carefully watched a dragonfly in flight?  Dragonflies can fly at speeds up to 45 mph and their aerial acrobatics are unparalleled.

Dragonflies are such agile fliers that they are able to avoid most potential predators.  We do have one bird species in Maine, the Purple Martin, which preys regularly on dragonflies.  In the southeastern United States, breeding Mississippi Kites take dragonflies.  Veteran hawk-watchers believe that these kites rely heavily on dragonflies for food during their fall migrations through Central America, which coincide with southern migrations of some dragonflies.  (Most dragonflies are not migratory).

Besides spectacular flying abilities, dragonflies have other similarities to birds.  Some species of dragonflies maintain breeding territories just as many birds do.  Male dragonflies are generally more colorful than females, just as is the case with many birds.

The best resource for identifying Maine dragonflies and the related damselflies is A Field Guide to the Dragonflies and Damselflies of Massachusetts (2nd edition) by Blair Nikula, Jennifer Ryan and Matthew Burne.  Nearly all the species found in Maine are covered.  Each species account has a couple of high-quality photographs and text on identification.  Details on ordering a copy are available at http://www.mass.gov/dfwele/dfw/nhesp/publications/nhesp_pubs.htm

[Originally published on June 12, 2010]

Blue-winged Warblers, Golden-winged Warblers and Brewster’s Warblers

By in Uncategorized

The warbler species in the genus Vermivora are small birds (four to four and a half inches long) with sharp, thin, pointed bills.   The bill is a great tool for capturing small insects, spiders and other invertebrates.  Vermivora means worm-eater, hardly an appropriate name for these birds unless one interprets worm to mean caterpillar.

Two species in the genus nest regularly in Maine.  Nashville Warblers occur throughout the state in the summer, nesting in second-growth or scrubby woodlands.  The margins of the many bogs we have in Maine provide great habitat for these birds.  Tennessee Warblers are much more common in the northern half of Maine.  These birds are residents of spruce-fir forests.  Tennessee Warblers depend on spruce budworms to feed themselves and their nestlings.

Blue-winged Warblers have nested sporadically in extreme southern Maine.  In the past few years, this species has been seen north of Portland during the breeding season.   This spring, Blue-winged Warblers seem more widespread than ever.  We may well be seeing the vanguard of a wave of this species expanding their breeding range north.

Blue-winged Warblers are gorgeous birds.  Males are yellow underneath except for white undertail coverts.  The head is yellow as well with a think black line through the eye.  The back is greenish-yellow and the wings are blue-gray with two prominent white wing bars.  Females are similar with the yellow on the head restricted to the forehead and with less prominent eyelines and wingbars than the males.

Alexander Wilson, the Scottish immigrant, covered the species in his American Ornithology, the first publication on the birds of North America.  The species was called the Blue-winged Yellow Warbler at that time and had been erroneously confused with the Pine Warbler until Wilson figured out two species were involved.

Blue-winged Warblers prefer over-grown old field and brushy habitats for nesting.  They occur in patchy fashion from Missouri, Iowa and Minnesota eastward from New Jersey to New Hampshire on the eastern seaboard.

Before Europeans colonized the eastern United States, Blue-winged Warblers migrated to Arkansas, Tennessee and Kentucky to nest.  As forests were cleared throughout the east, the Blue-winged Warblers expanded their range because favorable habitat was being created.  The species had reached northern Ohio by 1900.  Blue-wings were quite rare in Massachusetts in 1924 but now are found nesting widely across that state.

With the reversion of agricultural fields to forests and destruction of habitat for buildings, the amount of shrublands is decreasing, particularly in the northeastern United States.  As a result, Blue-winged Warbler population numbers are down in some parts of their range.

The incursion of Blue-winged Warblers into Maine may simply be a continuation of the range expansion that has been going on for over 200 years.  Warming of the climate and destruction of nesting habitat in southern New England may also be contributing to this apparent increase in Blue-winged Warblers in our state.

Blue-winged Warbler males have a distinctive, buzzy song consisting of two parts.  It is often described as “beee-buzzz”.  You can hear a recording at http://www.allaboutbirds.org

A closely related species to the Blue-wing is the Golden-winged Warbler.  Golden-wings occur rarely as migrants in Maine.  The two species overlap over much of their range.  Golden-winged Warblers have a yellow cap, a black throat, a broad, black mask on the sides of the face, and yellow wing bars.  Their song consists of four buzzy parts: zee zaa-zaa-zaa.

Blue-winged Warblers and Golden-winged Warblers occasionally interbreed to yield fertile hybrids.   Some early ornithologists collected some of these hybrids and described them as new species.  It took some genetics sleuth work to determine the true hybrid nature of these birds.

The most commonly encountered hybrid is called Brewster’s Warbler, the product of a first-generation cross between a Blue-wing and a Golden-wing.  The Brewster’s Warbler has the white underparts of a Golden-winged Warbler and often yellow wing bars but the black eyeline of the Blue-winged Warbler.  A Brewster’s Warbler was recently found by Becky Marvil (who provided the photograph), Marie Jordan and friends in Saco.

Now, it gets more complicated.  A Brewster’s Warbler may breed with either a Golden-winged Warbler or a Blue-winged Warbler.  A geneticist calls such a mating a backcross.  The offspring of the backcrosses fall along a continuum of Golden-wing and Blue-wing traits.  One variant, the Lawrence’s Warbler (also thought originally to be a new species) has the yellow underparts of a Blue-winged Warbler and the head pattern (bold black mask and black throat) of a Golden-winged Warbler.

The genetics of this system were worked out by Kenn Parkes in 1951.  You can download a copy of his paper (with paintings of different hybrids) here: Parkes.

[Originally published on May 29, 2010)

iPhone app for Haitian relief

By in Software

The authors of The Birds of the Dominican Republic and Haiti, published by Princeton University Press, have made an iPhone/iPod touch application available for download for $9.95 from the iTunes store.  The app has artwork, text and sound files for 58 of the 300 species found on this Caribbean island.  All proceeds from the app will go to Partners in Health and to Habitat to Humanity in relief of the devastating earthquakes that wreaked havoc in January.

The idea was the brainchild of Kent McFarland, one of the seven authors of the field guide and a research scientist at the Vermont Center for the Ecosciences in Woodstock, VT.  The artwork was provided by the Princeton University Press and the vocalizations were provided by the McCaulay Laboratory of Natural Sounds at the Cornell Laboratory of Ornithology.

You can find more information on the app here and here.

A Trip to the Galápagos Islands

By in Trip Report, Uncategorized

This column is the second of two on my recent trip to Ecuador.  The first column detailed some of the highlights of a visit to Amazonia.  In this column, I will cover our three-day excursion to the Galápagos Islands.

A visit to the Galápagos has been a dream of mine for a long time.  Charles Darwin visited these shores in 1835 on his around the world cruise on the H.M.S. Beagle.  His experiences with Galápagos mockingbirds, tortoises and finches were instrumental in his development of the theory of natural selection.  To see these animals and to walk the same land that Darwin trod was a tremendous thrill.

Our group flew from Guayaquil, Ecuador’s largest city, 500 miles west to the Galápagos archipelago.  We landed on the small island of Baltra.  A U.S. Air Force base was established there during World War II and now serves as one of two commercial airports in the Galápagos.

After clearing security and paying the required $100 visitor’s fee, we boarded a bus for a short ride to a ferry dock.  The passenger ferry took us just a few hundred yards to the large island of Santa Cruz, one of the four human-inhabited islands.

Brown Noddies (a type of tern), Brown Pelicans and Audubon’s Shearwaters flew above the water as we motored across the narrow channel.

Boarding another bus, we worked our way south towards the town of Puerto Ayora where we would spend three nights.

One of the two Los Hemelos (click to embiggen)
One of the two Los Hemelos (click to embiggen)

Our first stop enroute was Los Gemelos (The Twins), two huge volcanic depressions in the highlands of Santa Cruz.  Admiring one of these two sinkholes, I noticed a bird out of the corner of my eye.  It was a Warbler Finch, one of the 13 species collectively referred to as Darwin’s finches.  Within a few minutes, we had seen four others: Woodpecker Finch, Large Ground-Finch, Small Ground-Finch and Medium Ground-Finch.  I was thrilled!

With few natural predators, the animals of the Galápagos are well known for their fearlessness.  As our group stood around one of Los Gemelos, a Galápagos Dove perched only feet away from us.  This species is widespread in the archipelago but is declining.  Our tour guide told us we were lucky to see this species.  It is really a striking bird.

The dominant trees belong to the genus Scalesia and are members of the sunflower family.  Without seeing the flowers, I would never have suspected the Scalesia are related to our daisies.

Our next stop was Rancho Primacia.  A walk through this reserve yielded our first Galápagos tortoises as well as White-

Galápagos Tortoise
Galápagos Tortoise

cheeked Pintails, Galápagos Mockingbird, Yellow Warblers (the males have red feathers on their head) and a Common Moorhen.

The following day, we boarded a boat for a trip to Floreana, a two-hour cruise from Puerto Ayora.  We saw Nazca Boobies, Magnificent Frigatebirds, Audubon’s Shearwaters and

Marine iguanas on Isla Floreana
Marine iguanas on Isla Floreana

Elliot’s Storm-Petrel during the crossing.  Arriving at Floreana, we saw Galápagos sea lions and marine iguanas on the rocks near the dock.

We boarded a bus for transport to the highlands of the island.  I was particularly keen to see the Medium Tree-Finch, endemic to this island, but was skunked.  We did see lots of tortoises, Galápagos Flycatchers and a brief glimpse of a Galápagos Hawk.

Galápagos Flycatcher on Isla Floreana
Galápagos Flycatcher on Isla Floreana

We cruised to Devil’s Crown, a rocky outcrop just offshore.   Two Galápagos Penguins were perched on the shore with a Swallow-tailed Gull close by.  A Great Blue Heron was roosting there as well.

Blue-footed Boobies
Blue-footed Boobies

On Devil’s Crown, many Blue-footed Boobies and Nazca Boobies were roosting.  A couple of spectacular Red-billed Tropicbirds circled the boat.

The next day we sailed north for three hours to the small island of Bartholomé, adjacent to the large island of Santiago. Bartholomé is a young island, a little less than a million years old.  The soil is very poor; plants are sparse and well adapted to the arid environment here.  Geologically, Bartholomé is fascinating with lava tubes and magma formations.  Ornithologically, the island has little to offer so no new species were added to our list.  The snorkeling just offshore was spectacular with many fish species and sea turtles seen.

On our final morning, we visited the Charles Darwin Research Center in Puerto Ayora.  Walking in, we saw our last

Common Cactus Finch, Puerto Ayora, Isla Santa Cruz
Common Cactus Finch, Puerto Ayora, Isla Santa Cruz

Darwin’s finch species of the trip, Common Cactus-Finch.

At the institute, eggs of the 13 species of Galápagos tortoises are incubated and the young turtles raised for five years before release into their original habitat where the eggs were collected.  We saw Lonesome George, the last member of his species, found only on the small island of Pinta.

[Originally published on May 1, 2010]

A Trip to the Tibutini River, Ecuador

By in Trip Report, Uncategorized

I have just recently returned from nearly two weeks in Ecuador.  I was a participant in a faculty seminar in environmental science, sponsored by IES Abroad.  We were based in Quito but had time for excursions to the Ecuadorian Amazon and to the Galápagos Islands.  In today’s column, I will describe some of the Amazonian highlights.

The Tibutini Biodiversity Station (hereafter, TBS) was our destination for our Amazonian excursion.  The station, maintained by the University of San Francisco at Quito, is located along the Tibutini River, a tributary of the Amazon.  The Amazon is the largest river in the world and drains more water than the next ten rivers combined.  The Amazonian watershed encompasses 40% of the area of South America.  Amazonia is well known for its biodiversity.   But the TBS and the adjacent Yasuni National Park are exceptionally diverse.  One can argue that this region is the most diverse habitat on earth.  The area is at the center of a small zone where amphibian, bird, mammal, and plant diversity all reach their maximum levels within the Western Hemisphere.

To say that the TBS is remote is no exaggeration.  To get there, we flew south from Quito to Coca, a small town on the Napo River.  A couple of White-fronted Toucans gave us great looks in trees along the river.  White-winged Swallows, a close relative of our Tree Swallows, hawked insects over the water.

We continued our journey by boarding a large motor-powered canoe for two hours down the Napo River to a landing at a parcel of land, currently leased by a petroleum company.  After passing through the security check, we waited for a bus for the next leg of our journey.  Birding at the landing, we found Smooth-billed Anis, Purple Martins (soon to depart for North America, no doubt), a Roadside Hawk, a Palm Tanager, a Blue-gray Tanager and a pair of Chestnut-bellied Seedeaters.

The open-air bus carried us for two hours to the Tibutini River where we boarded another canoe for another two-hour trip to the landing at TBS.  As we docked, a Drab Water-tyrant, a flycatcher, hawked for insects along the riverbank.  Climbing the stairs to the dining hall, we had a nice look at an aptly named Sicklebill, a large hummingbird with a strongly curved bill, perfect for extracting nectar from the Heliconia plants growing near the dining hall.

TBS maintains a canopy walk and a canopy tower to facilitate the study of plants and animals high in the canopy of the dense forest.  On our first full day, we split into two groups, spending half the day on the canopy walk and half on the

tower.  I did the canopy walk in the morning.  It was wonderful to be 120 feet high and

Canopy Walk, Tibutini Biodiversity Station (click to embiggen)
Canopy Walk, Tibutini Biodiversity Station (click to embiggen)

above the canopy.  Scarlet Macaws, Blue-and-Yellow Macaws and Mealy Parrots flew above the trees.  I was surprised at the diversity and abundance of butterflies in the canopy.

In the afternoon, we climbed the tower alongside a huge ceiba or kapok tree, walking across to a solid platform 130 feet high.  Unfortunately, it rained most of the afternoon so soaring birds

Canopy Tower, Tibutini Biodiversity Station
Canopy Tower, Tibutini Biodiversity Station

were scarce.  We did get nice looks at Violaceous Jays, Dusky-capped Flycatchers, a Brown-throated Cotinga and a pair of striking Black-tailed Tityras.  On the hike back to the station, we had Rufous Motmot and Slate-colored Hawk.

The following morning was clear.  With high expectations, we boarded the canoe early for a float trip down the Tibutini River.   This trip was a wonderful way to see birds.  Highlights were Yellow-headed Vulture, Double-toothed Kite, Great Black Hawk, Bicolored Hawk, Black Caracara, Bat Falcon, Cobalt-winged Parakeet, Dusky-headed Parakeet, Tiny Cuckoo, White-breasted Nunbird, White-eared Jacamar, Ringed Kingfisher, Black-tailed Trogon, Purple Fruit-crow, Red-capped Cardinal, and Yellow-rumped Cacique.  White-banded Swallows, with steel-blue bodies and a conspicuous white band across the breast, were abundant.  Several were always in view, capturing insects above the river.

In the afternoon, we visited an oxbow lake in search of Hoatzins.  These birds are distant relatives of cuckoos and are the avian equivalent of cows.  The esophagus of a Hoatzin is modified as a fermentation chamber where symbiotic bacteria break down the leaves that the Hoatzin eats.  We took turns in a dugout canoe, paddling to the dense shrubs the Hoatzin prefers adjacent to the shore.  All of us had nice looks at these bizarre birds.  We also saw a pair of Greater Anis.  Locals refer to these birds as cooker birds because their group choruses sound like a pot of boiling water.

Before departing the next morning, we admired a pair of roosting Crested Owls.

[originally published on April 18, 2010]

Eastern Phoebe

By in Migration, Reproduction, Species Accounts

Fee’-bee!  Fee’-bee! You are probably hearing this buzzy song of the Eastern Phoebe in your neighborhood now.  These flycatchers spend the winter in the southeastern United States and return to our area to breed.  It’s good to have them back!

Unlike most flycatchers that have a single, stereotyped song, Eastern Phoebe males sing a second song.  The essence of the song can be captured as Fee’-b-be-bee.  In both songs, the first note is exactly the same.  For the Fee’ bee song, the second note is raspy.  The second portion of the Fee’-b-be-bee song is not as harsh and seems like stuttering.

Don Kroodsma found that Eastern Phoebe males alternate the two song types when they are singing at a high rate (about 40 songs/minute).  At 25 songs/minute, only three of four songs are Fee’-bee songs.  Males sing virtually only the Fee’-bee song if the singing rate falls below 20 songs/minute.  The pattern is clear; the reasons for the pattern are unknown.

Eastern Phoebes are easy to identify.  They have the upright stance of flycatchers as they sit on their perches.  The head is dark brown with dark eyes.  Phoebes lack the conspicuous light eye-ring of many of our flycatchers.  The upperparts of the body are olive-brown, slightly lighter than the head.  The wings have no wingbars.  The throat is white and the rest of the underparts are a buffy-white.  A distinctive behavior of Eastern Phoebes is their tail-wagging.  The tail is rapidly flicked downward and then slowly raised to its original position.

Eastern Phoebes like habitats that are only partly enclosed.  Suburban yards, roadsides, stream banks and orchards are all good habitats.  Within their nesting territories, phoebes have several perches that they habitually use.  A phoebe will sit on its perch, looking for an insect in flight.  When a potential meal is seen, the phoebe will sally forth and grab the insect in flight, returning to a perch.

These birds seem particularly fond of beetles although wasps, ants, grasshoppers and flies are taken on the wing as well.  Sometimes, millipedes and spiders may be taken from the ground.

Nests of Eastern Phoebes are cemented to a vertical surface and are made of an outer layer of mud and a softer, inner lining of grass and other soft materials.  Before European settlement, Eastern Phoebes probably nested on cliffs and ledges.  As Europeans colonized eastern North America, Eastern Phoebes easily adapted.  They now readily nest on rafters and under the eaves of our houses and barns.  In the 19th century, common names for the Eastern Phoebe  were Barn Pewee and Bridge Pewee.

Phoebes will use the same nesting site from year to year, often building the new year’s nest on top of the old one.  Their faithfulness to a nesting site was first shown by John James Audubon who tied some silver wire to the legs of nestling birds captured at their nesting site in Pennsylania.  Sure enough, two birds returned to the same area the next year.  Aubudon was apparently the first bird bander in North America!

Audubon’s results were fortunate ones.  Other biologists have shown that Eastern Phoebes are seldom faithful to the area where they were hatched and fledged (the natal site).  In Indiana, none of 3,594 nestlings were found in the area in subsequent years.

Like most perching birds, adult Eastern Phoebes do show strong fidelity to a nesting site.  Nearly 90% of pairs use the same nest site for second clutches.  The fidelity from year to year is equally strong.  Lots of other birds show similar behavior with low natal site fidelity and high nesting site fidelity.

Eastern Phoebes are industrious parents.  It is normal for a pair to raise two broods in a summer.  Each brood usually has five babies, although broods as high as eight have been reported.  Unfortunately, phoebes are often the victims of female Brown-headed Cowbirds which lay a cowbird egg in a phoebe nest, fooling the phoebes into raising a greedy cowbird chick along with their own chicks.

Data from the Breeding Bird Survey (begun in 1966) indicate that Eastern Phoebe populations are holding their own.  The overall density of this species is highest in the New England states.

The species winters from Virginia to Texas and eastern Mexico.  The center of the wintering population is in eastern Texas and the panhandle of Florida.

The replacement of square concrete culverts and small wooden bridges with circular, corrugated metal pipes has made such sites unusable for nesting.  Biologists have discovered that flat nesting platforms placed in circular culverts are readily accepted as nest sites by Eastern Phoebes.

[originally published on April 4, 2010]

Two New Bird Books and Ospreys in Maine

By in Book Reviews

A couple of new bird books have crossed my desk that I think will be interest to birders.  The first is a new field guide to the birds of the eastern part of our continent.  Sterry_SmallPublished by Princeton University Press, this guide is titled Birds of Eastern North America: A Photographic Guide, written by Paul Sterry and Brian Small.

The old saw that a picture is worth a thousand words certainly applies to nature guides.  The most important part of any bird field guide is the illustrations.  Most field guides reply on paintings or drawings by skilled artists.  The artist can draw or paint a bird from an angle to best show its distinguishing characteristics.  Nonetheless, some people may consider even the best paintings to fail to capture the living quality of a bird.

Alternatively, photographs are true representations of how a particular bird looks under the lighting and background conditions when its picture was snapped.  Some birders find it far easier to match an unknown bird with a photograph rather than a painting.

Acquiring suitable bird photographs for a field guide is a challenge.  Birds don’t pose for the camera, lighting may wreak havoc on the true color depiction of a bird and getting close enough to a bird for a crisp, close-up is tough.  Despite these challenges, Sterry and Small have produced what I believe is the finest photographic field guide of eastern birds.

Both authors are highly skilled nature photographers.  Small is the Photographic Editor for Birding magazine and I have admired his photographs for years.  The photographs in this guide are crisp, informative and, in many cases, stunning.

The book is organized like most field guides with a brief introduction to bird anatomy and plumages.  The majority of the text is composed of species-by-species descriptions of birds in the currently recognized checklist order.

The left page has text on two or three species, giving, in telegraphic style, information on identification features, different plumages and similar species.  Information is provided on the status of the species and tips on how to find each species.  One or two small photographs for each species are given on the left-facing page.  A distribution map is provided as well.  The right-facing page is devoted solely to photographs; many seem to leap out of the page.

At the end of the guide, you will find a section called Out of the Ordinary where vagrants to the east, like Barnacle Goose and Ivory Gull, and exotic waterfowl, like Mandarin Duck and Common Shelduck, are briefly covered.

Bright Wings: An Illustrated Anthology of Poems about Birds is a charming book.  The book is edited by Billy Collins, former Poet Laureate of the United States.  The poems chosen span two millennia, from the Roman poet Catullus through brightwingsChaucer, Henry David Thoreau, Thomas Hardy, and Emily Dickinson to more recent poets like Gray Snyder, Wallace Stevens, Jane Hirshfield, Mary Oliver and Billy Collins himself.

I had to smile when I realized that the bird poems are arranged in checklist order, just like a field guide!

But the poetry is only a part of the charm of the book.  For many poems, David Sibley has provided a lovely portrait of the bird featured in that poem.

Osprey Egg Contamination

The Biodiversity Research Institute in Gorham has released its troubling report on contaminants in the eggs of Casco Bay Ospreys.  Polychlorinated biphenyls (PCBs) and other organic contaminants were found at levels known to adversely affect chick development in chickens.

You can download the whole report at http://www.briloon.org/contaminants/index.php

Maine Butterfly Survey

The Maine Butterfly Survey, a five-year project to map the distribution and abundance of the butterflies and skippers of Maine, is beginning its fourth year. This project relies heavily on volunteers. The first three years have yielded over 4300 records (specimens or photographs). Volunteers have established four new state records and a large number of county records in the first three years of the project. You can see all of the records to date at the MBS website: http://mbs.umf.maine.edu/

Please contact me if you are interested in becoming a member of the MBS team.

[originally published on March 21, 2010]

An Ornithological Reading List

By in Book Reviews

A reader of this column, Tim McCormack, asked me to suggest a reading list of bird books to provide a good overview of the field of ornithology.  After sending him some suggestions, it occurred to me that other readers might be interested in those suggestions as well.

The number of bird books is huge so the books I discuss below are an eclectic assortment.  I have greatly enjoyed reading all of them and found each informative.

The best college-level textbook on the market is Frank Gill’s Ornithology.  The current edition was published in 2007 so is quite up to date.  Gill’s text is highly readable; it is chockfull of information without being technical.  The book has many figures and photographs to accompany the text.

The Handbook of Bird Biology is a massive reference volume created by the Cornell Laboratory of Ornithology.  The book serves as the text for their long-standing Home Study Course in Biology.  The book can be purchased without subscribing to the Cornell Lab course.

The level of the text is similar to Gill’s Ornithology.  The Handbook is a cooperative effort with each of the ten chapters being written by one or more ornithologists who are specialists in a particular topic.

The beauty of bird song captivates birder and non-birder alike.  There is an embarrassment of riches on this topic.  A good starting point is Don Kroodsma’s The Singing Life of Birds.  Kroodsma is a prolific researcher on bird vocalizations, authoring many technical articles on the subject.  This book, however, is aimed at a lay audience.  Kroodsma explains how our eyes can help our ears by describing sonagrams, computer-generated graphs of sounds.

The text is a collection of narratives of many different excursions that Kroodsma took to record vocalizations.   You will go with him close to his home in Massachusetts to record a Hermit Thrush, to Costa Rica to record Wattled Bellbirds and to Oregon to record Bewick’s Wrens.   In each narrative, Kroodsma explains the particular hypothesis he is testing and presents many sonagrams on the species of interest.  Each narrative is a primer on how to do science.

The book comes with a CD so you can listen to the actual recordings used to generate the sonagrams in the text.

Another fascinating book is Why Birds Sing by David Rothenberg.  The author is a professor of philosophy and a talented jazz clarinetist.  His book explores the interface between bird song and the arts.  By interviewing scientists and composers, he explores the meaning of bird song, both to avian and human ears, to try to determine why birds sing.  I enjoy books that meld different disciplines to construct intriguing connections.  This book succeeds in this regard.

Lots of mammals and insects migrate but none can hold a candle to birds in the extent of their migratory movements.  A wonderful introduction to bird migration is Scott Weidensaul’s Living on the Wind: Across the Hemisphere with Migratory Birds.  Weidensaul is one of our most gifted nature writers.  His lyrical prose takes us to many parts of the world to vicariously experience a migratory spectacle.  We go to see the Sandhill Cranes in Nebraska, Red Knots in Delaware, the thousands of songbirds on the Gulf Express, struggling to get to the shores of Gulf Coast states after a non-stop flight from Mexico, and the river of tens of thousands of Broad-winged Hawks passing over Veracruz, Mexico.  By the end of the book, you will have experienced fully the phenomenon of bird migration.

I enjoy books that focus on a single bird species.  One of my favorites is Susan Smith’s The Black capped Chickadee: Behavioral Ecology and Natural History.  Smith has worked with chickadees for over four decades.  She reviews all aspects of the biology of our state bird in a highly readable style.  Much of the research she summarizes is her own.

To get a flavor of field ornithology in the tropics, you will not go wrong by reading Don Stap’s A Parrot with No Name.  Staps went on an extended expedition to the Peruvian jungle with a number of ornithologists from Louisiana State University.  He takes you to the jungle with all the joy, frustration and anxiety such an experience brings.

Finally, a couple of books on ornithological history.  Joseph Kastner’s A World of Watchers gives a history of ornithology and birding in North America, mostly focusing on the 19th and 20th centuries.  For a fascinating account of the life of John James Audubon, you can’t beat Richard Rhodes’ John James Audubon: The Making of an American.

I’d love to hear of your favorite bird books.

[originally published on March 7, 2010]

«‹ 35 36 37 38›»