Birds Behaving Badly / Brood Parasites

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Brown-headed Cowbird, Molothrus ater

Amazing and unusual techniques have evolved for the defense and propagation of species in the Animal Kingdom.  For instance, the squid ejects its veil of ink to cover its retreat; the skunk squirts its malodorous spray; the porcupine has its quills; and the opossum feigns death, even with the the drooling mouth, when all else fails.

Killdeer

Killdeer, Charadrius vociferus

In the Avian class the Killdeer fakes a broken wing to lure predators away from the nest.  Some species have a plumage that is perfect camoflage for their preferred habitat.  The Fulmar is a stinking seabird whose name literally means “foul gull”, fending off any predator with a sense of smell.  Both the bird and eggs reek, with the chicks having the additional defense of vomiting bright orange, sticky, foul matter whenever threatened.   Burrowing Owl chicks, when left unattended in their burrows, make a rattlesnake-sounding hiss when they sense danger.  It fools everyone except the rattlesnakes.

Burrowing Owl

Burrowing Owl, Athene cunicularia

All of these seem logical, effective, and fair.  But then you have brood parasitism.  Now mother nature has gone too far–this really pushes the envelope of what should be allowed.  Where is the Supreme Court when you really need it?  Of course I say this in jest, but doesn’t it rile you a little to see this in action, and doesn’t it temp you to intervene?

Brood parasites are birds that lay their eggs in the nests of other birds, either of the same species (intraspecific),such as Goldeneye or Cliff Sparrows, or other species (interspecific) such a Brown-headed Cowbirds or European Cuckoo. This allows them to avoid the time and energy consuming chores of nest-building, incubation, feeding, etc.  Some birds like the cowbirds use this technique exclusively, while others only occasionally, probably when overwhelmed with the thought of feeding one more chick.  Luckily only 1% of the approximately 10,000 avian species have “learned” this shortcut and I hope it doesn’t spread.

Mottled Duck

Mottled Duck, Anas fulvigula

The parasitizing bird has developed various devious techniques to pull off this charade.  The female lays the egg quickly, to get in and out before the host female returns to the nest. She often cleverly kicks out one host egg in hopes the host doesn’t sense the newcomer.  Can birds really count?  The egg colorations are often, but not always, closely matched to the host eggs.  The parasite eggs often have shorter incubation times and the parasite chicks grow quickly, monopolizing the food supplied by the host parents.  Some parasite chicks have a mandibular spike which they use to puncture the other eggs or wound the rival chicks.  The European Cuckoo chick has a depression on its back that allows him to hoist the other chicks to the rim and push them out of the nest, attempting to be the only surviving chick.  Cowbird chicks, on the other hand, tend to tolerate their “siblings”.

Song Sparrow

Song Sparrow, Melospiza melodia

Many brood parasites will only lay eggs in the nest of one or two similar host species, oftentimes the same species that raised them.  The Cowbird, however, is not so picky, having 221 different known hosts. As many as 70% of Red-eyed Vireo nests are parasitized by Cowbirds. Song Sparrows have very similar eggs to the Cowbird and are usually fooled into being the parent, but Catbirds and Robins have clearly different plain eggs and usually reject the newcomer.

Red-eyed Vireo

Red-eyed Vireo, Vireo olivaceus

The host birds are not completely tolerant of this outrage.  Many apparently can count and discard or puncture the new egg.  Others work hard to build secretive nests and wage a staunch territorial defense.  Some abandon the parasitized nest, while others just rebuild another nest on top of the first.

Host birds can be put into the categories of “Acceptors” or “Rejectors”.  Some birds, such as the Eastern Phoebe, have clearly different eggs from a Cowbird but accept, incubate, and raise the parasite bird.  This may be because rejection has its own risks.  Apparently the parasite birds patrol the chosen nests, (the Mafia Hypothesis) and retaliate by destroying the nest and nestlings if its eggs or chicks are harmed.  Call in the FBI.

Eastern Phoebe

Eastern Phoebe, Sayornis phoebe

In essence we are witnessing an evolutionary arms race between the reproduction techniques of brood parasites and the standard practices of the other birds.  The Cowbirds seem to be doing quite well.  A female may lay as many as 3 dozen eggs in host nests during the breeding season. Think of the free time for shopping and dining this bird acquires, with no need for nest building and parental chores.  Even some fish and insects have adopted these techniques, but there clearly must be a downside since the phenomenon is still fairly uncommon.  I’m rooting for the violated birds to fight back against this injustice.  Do the birds feel as victimized by this as we humans would?  Could there even be a “Nesting Code of Ethics” that will eventually win the day?  Several million years from now we will know the answer.

Red-winged Blackbird / The Epaulet Bird

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Agelaius phoeniceus

Epaulets have been around since the 17th century signifying military rank, authority, and strength, projecting power over all who may doubt. Over the years they got bigger and more gawdy with ridiculous tassels and fringes to where they got into the way of actually fighting the war.  A colorful form of them also appears on the academic robes at each graduation season.  Chief Justice Rehnquist surprised us when he donned them on his judicial robe at the impeachment trial of President Clinton.  In all cases they make a statement; I’m important, don’t mess with me.

King Oscar II of Sweden

King Oscar II of Sweden

Who has not welcomed the trill of the Red-winged Blackbird in early spring, beating its rivals to the prime marshland and grassy fields, staking out a breeding territory for the season.  I know this is a common North American bird, seen coast to coast and Canada to Mexico (some say the most numerous native North American bird), but there are some interesting tidbits about it I did not know.

Red-winged Blackbird

Red-winged Blackbird

The male’s epaulet is a striking field mark, but not always displayed.  He flaunts the wide red and narrower yellow bands when he’s perched on the tall cattails, attracting a mate, or aggressively defending his large nesting territory.  He is a polygynous bird with each male having up to 15 mates and several active nests in his territory.  For all his loud singing, epaulet displaying, and cocksure bravado, it is interesting to note that DNA studies have shown that up to half of the nestlings in his several nests have been sired by other males.

Defending the territory?

Defending the territory?

The epaulet can also be concealed, almost completely when that becomes advantageous, perhaps when sneaking around a rival male’s nesting territory.  The nests are generally low in marshy vegetation, carefully constructed by the female from woven grasses, sometimes several feet in length.  A Californian subspecies has lost the yellow-band and is called a “Bicolored Blackbird”.

Red-winged Blackbird, female

Red-winged Blackbird, female

The female and juvenile birds are barely distinguishable, each with a streaky plumage and whitish supercilium.  I remember spending quite a while watching and photographing this unusual large “sparrow” several years ago, before finally figuring out it was a female Red-winged Blackbird.  I understand this is a common experience among fledgling birders.

Male in winter plumage

Male in winter plumage

The summer diet is primarily insects, while in the winter it’s seeds.  This allows the bird to be a short-distance migrator, wintering just south of the Mason-Dixon Line.  Here in the mid-Atlantic states we are near the northern edge of the wintering grounds, and depending on the severity of winter you may see the birds all year long.  The winter plumage of the male shows the upper body feathers edged in buff (see picture above), which apparently gradually wears off giving the all-black appearance of spring.

Mixed flock at Blackwater NWR

Mixed flock at Blackwater NWR, click on pic for full screen view

These birds typically form large mixed flocks with cowbirds, grackles, and starlings in the fall and winter, ranging across the harvested fields and wetlands.  I’ll never forget the huge flock I saw one winter day at the Blackwater NWR in Dorchester County, Maryland.  The distinct scattered red epaulets were still visible from a great distance as the flock of thousands wheeled around the brown marshland.

Book Review: Birds of a Feather by Colin Rees and Derek Thomas

Yellow-crowned Night Heron

Yellow-crowned Night Heron, Nyctanassa violacea

Birds of a Feather, Seasonal Changes on Both Sides of the Atlantic, by Colin Rees and Derek Thomas, published by Matador, copyright 2014, 358 pages

Everyone needs a library of “bathroom books”.  These are the books with short concise chapters with a message or thought for the day, that you remember as you make your way through the 24 hours.  Its works best when the chapters are each actually dated and the text reflects our seasonal changes. I’ve filled this bill with “A Year With C.S. Lewis, Daily Readings from His Classic Works”, “The Intellectual Devotional” by Kidder & Oppenheim, and others, but my new favorite is “Birds of a Feather”.

Carolina Chickadee

Carolina Chickadee, Poecile carolinensis

The authors are longtime friends, fellow birders, naturalists, and conservation activists living on opposite sides of the Atlantic pond.  Colin Rees is past president of the Anne Arundel Bird Club in Maryland and lives in nearby Annapolis on the Chesapeake Bay.  His entries have special appeal to me as he sees “my birds” and reports on birding hotspots that I have visited.  His observations have heightened my enjoyment of this area.  Derek Thomas, on the other hand, brings a whole new perspective and “new birds” to light.  He lives and birds on the rocky, Maine-like Gower Peninsula in Wales, and recently retired as Chairman of the Wildlife Trust.

Eastern Phoebe

Eastern Phoebe, Sayornis phoebe

The book is a mixture of short chapters alternating between authors, describing bird walks, wildlife observations, science, changing habitats, environmental issues, and conservation.  One of the appeals of this book is the contrasting homes of the authors.  The flat, tidal wetlands of the Chesapeake estuary with its 4000 miles of shoreline, marshes, creeks and rivers vs. the rocky, windswept limestone cliffs of seaside Wales.  We locals think of Maryland and the Chesapeake as old, colonized by Europeans in the 17th century, but see real antiquity when Thomas describes birding around the 12th century ruins of Wales.

Brown Creeper

Brown Creeper, Certhia americana

Both locations experience the four seasons, which makes for interesting chapters throughout the calendar year.  The Chesapeake has some buffering effects from the nearby Atlantic but still has an extreme annual temperature change with water temperatures going from 86 F in summer to 34 F in winter.  I can testify that the Arctic winds whipping down the bay can be bleak in January and February.  Likewise the Gower Peninsula is ravaged by an average of 50 Atlantic gales each year.  Fog is common due to the tempering effects of the warm Gulf Stream.  Thomas suggests that the moodiness created from the rapid changes in the weather has influenced the writing of local poets, including Dylan Thomas.

Canada Geese

Canada Geese, Branta canadensis

The Atlantic barrier has isolated the Old World from the New enough to allow the evolution of very different passerines.  Except for the rarity that is blown our way by the freak storm, one doesn’t see these birds unless you travel.  Just the names are inviting:  wheatears, pipits, stonechats, whinchat, chaffinches, and wagtails.  We do share many of the migrating shorebirds and waterfowl.

Red-bellied Woodpecker

Red-bellied Woodpecker, Melanerpes carolinus

I hesitate to offer criticism of a book I really enjoyed and learned from, but that’s what a reviewer should do.  The authors, I think are overly pessimistic for the future of our planet and this gloom comes through in many of the chapters.  They cite the growing numbers of endangered birds, loss of habitat, climate change, etc.  I recognize these issues but also see a very different world today than when I started birding in the 1960’s and 70’s.  At least in this country the air and water are cleaner, we are much more aware of our environment, and we are restoring critical habitats across the continent.  The Chesapeake Bay’s submerged grasses, which are a barometer of the bay’s health, are flourishing again.  There are setbacks, like the Gulf oil spill which is featured prominently in the book, but they are becoming less frequent.  I admit the habitat loses in the Third World, such as the  rain forests, are critical.  I’m just saying, let’s celebrate some of our successes and not overdo the gloom and doom.

Osprey

Osprey, Pandion haliaetus

These authors have created a great little book to start each day.  As Mr. Thomas said, “One of the most wonderful things about the natural world is that it doesn’t answer back; it’s an escape from the everyday problems of life and a refuge where I can forget the day-to-day trivia, which becomes less important as I get older.  Communicating with nature is a one-way process; it speaks  to us  in pictures, sounds, and emotion…and much of the world seems not to appreciate its wonders…nothing compares with the simple pleasure of looking at a flower or bird.”