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Saturday, June 27, 2015

Dangerous Liaisons: Lawrence's Warbler and Brewster's Warbler

[Port Huron SGA. May/June 2015]

Specialty species. Target species. Endemic species. Where would Birding be without the fundamental concept of a "species"? But, what exactly is, or is not, a species? In this post we consider the status of two uncommon warblers -- Brewster's and Lawrence's -- observed recently in the avian-rich tracts of Port Huron SGA (State Game Area).

Liaisons between different species are not unknown in the Animal kingdom -- in the US, Indigo and Lazuli Buntings, Rose-breasted and Black-headed Grosbeaks, Black Ducks and Mallards, among others, will sometimes hybridize where their ranges overlap. 

According to the American Genetic Association (in an article by Richard G. Harrison and Erica L. Larson), a species can be defined as:

... populations that are diagnosably distinct, reproductively isolated, cohesive, or exclusive groups of organisms. 

We start with Golden-winged Warbler, seen here from an image taken at Magee Marsh in 2013:

Golden-winged Warbler seen at Magee Marsh
The Golden-winged Warbler has a grey back, white undersides and a distinctive facial pattern that includes a black mask and chin; the crown and wing-bars are yellow.

The Blue-winged Warbler, on the other hand:

Blue-winged Warbler seen at Port Huron SGA

... shows the same grey back, but white wing-bars, black eyeline and a yellow body. Both warblers have distinct but similar buzzy songs.

The expansion in the Blue-winged Warbler's range Northward (possibly due to rising temperatures), permeates the invisible geographic boundary between the two species and this range encroachment dilutes one of the important criteria in the definition of a species -- namely, that of "reproductively isolated" populations. Indeed, both Blue-wingeds and Golden-wingeds will interbreed and the resulting liaison does produce viable offspring.

When this happens, a species may come under the threat of genetic extinction -- indeed, this is precisely the case with the Golden-winged Warbler. This species has suffered a precipitous decline in its population and is currently classified as "Near Threatened". Concomitant with the decline in the number of Golden-winged's has been a rise in Brewster's and Lawrence's Warblers. Both of these warblers are the product of this inter-species liaison and are increasingly being reported in e-Bird:

Brewster's Warbler
Brewster's Warbler shows the back of a Blue-winged -- grey with white wing-bars -- but the golden crown and white undersides of a Golden-winged. The mask of the latter is absent; replaced instead, with the black eyeline of the Blue-winged's.

Lawrence's Warbler seen at Port Huron SGA
Lawrence's Warbler, on the other hand, shows the black facial markings of the Golden-winged, the yellow body of the Blue-winged and two wing-bars -- each of which could belong to either species.

In an excellent article, the genetics behind these hybrids are explained. And, it comes to light that the Lawrence's Warbler hybrid is the rarer of the two -- requiring the presence of recessive genes from both parents; while Brewster's Warbler are much more common.

Brewster's Warbler
Both hybrids are attractive in their own right, but the Lawrence's is truly spectacular:

Lawrence's Warbler
So, while both Brewster's and Lawrence's Warblers are special, intriguing and genetically distinct, one thing they are not, however, are species in their own right. 

Saturday, June 13, 2015

Lake St. Clair in Spring: Wood Duck, Virginia Rail and Yellow Warbler

[Lake St. Clair Metropark. May 2015]

The real estate adage of "location, location, location!" may, with some creative license, freely be adapted to "habitat, habitat, habitat!" within the context of the birding world. For, diversity in habitat implies, inevitably, a corresponding diversity in species as well. And, it is precisely this trait that makes Lake St. Clair Metropark a magnet for birders and birds alike.

A mix of water bodies, woodland, marshes and lakeshore mudflats means that, in season, waterfowl, songbirds, marsh birds and shorebirds may all be found at this renowned hotspot. Accordingly, this post will briefly profile:
  • Virginia Rail
  • Great Blue Heron
  • Red-winged Blackbird
  • Swamp Sparrow
  • Marsh Wren
  • Belted Kingfisher
  • Wood Duck
  • Yellow Warbler
  • Indigo Bunting
  • Baltimore Oriole
We start with the rallid -- Virginia Rail can be reliably found at the Metropark. In particular, the ponds found by exiting the first foot bridge (connecting the meadow loop) usually hold a pair or two.

The Virginia Rail is a cryptic marsh bird that is found, in Summer, across the Northern US in a wide swath from East to West. It is migratory in habit and wisely moves to warmer climes in Winter.

While this rail is a small bird, in contrast, the massive Great Blue Heron outsizes it by a couple of orders of magnitude -- here seen in majestic flight over the marsh

The reed beds of the marsh support blackbirds, wrens and sparrows. First, we present a scene that becomes ubiquitous in Spring: Red-winged Blackbirds:

Sharing prized perching points with the blackbirds are Swamp Sparrows:

.. as well as Marsh Wren -- now suddenly appearing impossibly numerous having only recently been entirely absent:

The trill of the wrens is interrupted by the call of a Belted Kingfisher which pierces the air with its machine gun like rattle:

As the Kingfisher flies over the ponds hunting for fish, a Wood Duck drake quietly escorts his mate toward hidden channels for a secret rendezvous with romance on his mind:

Farther afield, in the woodlands, Yellow Warbler is a common breeding species and their songs are heard at every short interval:

Joining the warbler as a breeder is another nester -- the Baltimore Oriole:

Unlike the Oriole, the Indigo Bunting seen here is merely passing through:

The ecological devastation that has historically, and grotesquely, scarred our land seems a distant memory when, in restored or unspoilt habitats, the true wealth of our natural inheritance shines in full and glorious effulgence through wildlife.

Saturday, June 6, 2015

Magee Marsh The Conclusion: Scarlet Tanager, Northern Bobwhite, American Woodcock and More

[Magee Marsh, OH. May 2015]

Amidst the Warblermania at Magee, those not completely swayed by the parade of colorful "avian butterflies", will doubtless seek reward in the discovery of other families of birds that, while not entirely comparable  to their warbler brethren, are otherwise no less in form or feature.

For those who thus expand their birding horizons, this gain in the overall equilibrium in species is made possible by the other migrants present -- delightful Thrushes, Orioles, Tanagers, Sparrows, Vireos, and even sometimes the unusual and unexpected -- such as an errant Northern Bobwhite blown off its migration course.

American Woodcock

In May, the swarming crowds are an infamous phenomenon at Magee, and, while the swooning masses shriek and lurch in frenzied unison to the cries of "Blackburnian" or "Mourning Warbler", the phlegmatic birder, wisely unperturbed, neglects not to scour low nor scan high -- perhaps a Woodcock lurks in the leaf litter; or, an Owl sits motionless as stone on a branch. Both avian treasures that could be cruelly, and thoughtlessly, overlooked in a feverish quest for feathered celebrities.

American Woodcock
And, this is precisely the aim of this blog post: to profile the migration at Magee minus the warblers -- such as this beautiful Baltimore Oriole:

At the visitor center, Barn Swallows nest in the building and can be seen perched on the railings early in the morning:

An impossibly camouflaged Eastern Screech Owl -- a species, in full confession, this blogger has always seen second hand at Magee; benefiting from the prior sighting efforts of other birders:

Eastern Wood Pewee:

Grey-cheeked Thrush:

This beautiful Northern Bobwhite created a minor pedestrian traffic jam in the parking lot as gleeful onlookers-turned-photographers employed their smartphone cameras to capture the scene:

Purple Martins are our largest swallow -- and while almost impossible to photograph in flight, they can be fairly easily digitally captured outside their next boxes:

Rose-breasted Grosbeak:
Ruby-crowned Kinglet:

Red-eyed Vireo:

Swainson's Thrush

Scarlet Tanager:


White-throated Sparrow:

and, Warbling Vireo: