Friday, August 22, 2014

Know Thy Herons

[SW Florida. August 2014]

The definite word on the family Ardeidae is the highly scholarly (and equally expensive) "The Herons" (recommended for all birders who are not averse to occasionally dabbling in Ornithology).  In this definitive 400-page treatise, in addition to individual species accounts, some fascinating facts about the heron family emerge:
  • The first herons arrived on the scene in the Eocene period 60 million years ago
  • There are 64 species of herons extant today ranging in size from the Least Bittern to the Goliath Heron (the former barely reaching the latter's ankles)
  • Linnaeus was the first to group all the herons under one genus (Ardea) in 1788. Today the family includes 21 genera comprising day herons, egrets, bitterns, pond herons, cattle egrets, tiger herons, night herons and more
  • Long and slender -- everything about a heron is long and slender; from overall body shape to the shape of individual body parts such as the neck, bill, legs, and toes
  • The kink in the heron's neck is a distinctive evolutionary adaptation and is a result of an elongated 6th cervical vertebra. This unique "anatomical hinge" is what gives the heron its powerful fish-catching strike.
We begin with a quick review of the features that make a heron a heron:

Tricolored Heron seen at Tigertail Beach. This side view does justice to its long, spear-like bill.

The Tricolored Heron is, in many ways, the archetype heron. The first thing that stands out is the impressively long, spear-shaped bill. The more aquatic and fish-dependent the heron, the longer and slimmer the bill. In counter example, the Cattle Egret has a much shorter bill -- which is perfect for an insect eating "ground heron".

Great Blue Heron seen at Bunche Beach

Our next heron, the Great Blue, also fits into the typical heron mold: the flexible, long neck with the prominent kink; the bill here, while proportionally not as long as the Tricolored's, is still long but appreciably stouter -- a feature that helps it catch larger fish.
Yellow-crowned Night Heron seen at Ding Darling (Nov 2013). Note the powerful bill.

It is the serial crab predator, the Yellow-crowned Night Heron, however, that typifies food-based bill specialization in the herons. Compared with the Tricolored's, the night heron's bill is much more compact as well as thicker -- a powerful bill that is perfectly suited for preying on crabs and crayfish.

Little Blue Heron seen at Tigertail Beach

Compared to the Yellow-crowned night Heron, both the Little Blue Heron and the Reddish Egret display the typical characteristics of fish-eating herons -- long necks and slender bills.

Reddish Egret seen at Tigertail Beach

While the basic anatomy of both the Little Blue Heron and the Reddish Egret is similar, their foraging habits are not.

 Little Blue Heron foraging at Little Estero Lagoon (Sept. 2012)

The Little Blue Heron is a slow and deliberate hunter and uses "Head Swinging" (see above) -- its long neck swaying over the water not unlike the movement of a snake. Compare this with the foraging antics of the Tricolored Heron and Reddish Egret.

The Tricolored Heron (as the text explains) frequently uses Open Wing Feeding which is preceded by Stalk, Hop, Run and then with Open Wings, Lunge and Strike.

Tricolored Heron feeding sequence observed at Tigertail Lagoon

When it comes to foraging, however, no American heron is perhaps as energetically entertaining as the Reddish Egret. While the stoic hunters like the Great Egret and Great Blue Heron use a lethargic "wait for the prey" technique, the Reddish Egret is an active forager -- employing all of the techniques of the Tricolored plus Canopy Feeding.

Reddish Egret at Bunche Beach in feeding sequence

The white morph of the Reddish Egret displays exactly the same behaviors. It is a little known fact that the occurrence of the white morph varies by geography -- from a low of 5% for Reddish Egrets found on the Texas coast to a high of 90% for those on Great Inagua in the Bahamas.

Reddish Egret at Bunche Beach in feeding sequence

About 15% of the Reddish Egrets in Florida are white morphs (incidentally, compare this to less than 1% for the occurrence of Great White Herons among Great Blues).

The scientific study of our avifauna sheds tremendous insights into the world of birding; and, as a consequence, the pursuit of birds whether as a sport, recreational obsession, or photographic quest is greatly enriched when supplemented by Ornithological accounts that are now more accessible than ever to the birding enthusiast.

Other members of the heron family:

 Indian Pond Heron seen at Sultanpur, India, July 2009

Least Bittern seen at Wakodahatchee Wetlands, July 2009

Little Bittern seen at Dal Lake, India, July 2012

Purple Heron seen at Bhindawas Bird Sanctuary, India, July 2012

White-faced Heron seen at Anglesea Beach, Victoria, Australia. February 2012

Sunday, August 17, 2014

Yellow-throated Warbler plus Brown-headed Nuthatch and Red-bellied Woodpecker

[SW Florida, August 2014]

While shorebirds are stealing the limelight in early August, some woodland species can provide a change in birding scenery when stalking peeps to identify bill length and leg color on mudflats runs the risk of becoming tiresome. At a couple of hotspots (Tigertail and Serenity Walk), the following species provided just such a respite:
  • Yellow-throated Warbler
  • Great-crested Flycatcher
  • Brown-headed Nuthatch
  • Red-bellied Woodpecker
A recent excursion to Corkscrew Swamp had provided some encouraging warbler sightings (Black-and-white Warbler, Northern Parula, Northern Waterthrush) and this trend received further impetus with the sighting of an early arrival from the North: the Yellow-throated Warbler at Tigertail Beach on Marco Island.

Yellow-throated Warbler seen at Tigertail Beach

Southwest Florida is not known to be a breeding hotspot for warblers compared to our Northern States that can boast up to 20 species. SW Florida, by comparison, has just a few -- Northern Parula, Common Yellowthroat, Yellow, Pine and Prairie warblers (an excellent resource for which is the Florida Breeding Atlas); however, come Fall and Winter, the tables are turned as warblers flee their increasingly frigid Northern homes and SW Florida becomes a mecca for wintering warblers -- including Yellow-throated Warbler.

Yellow-throated Warbler seen at Tigertail Beach

While Yellow-throated Warbler is commonly seen as an over-wintering warbler here, August marks the earliest month that this blogger has witnessed it in these parts. The warbler itself is unmistakable with its white undersides, yellow throat, bold facial markings and grey upperparts all lending a clean, crisp look to this Southeastern Warbler.

Yellow-throated Warbler seen at Tigertail Beach

This stunning warbler was seen in a mixed feeding flock that included a Prairie Warbler and Great-crested Flycatcher:

Great-crested Flycatcher seen at Tigertail Beach

An excellent birding hotspot en-route to (or from) Marco Island is Serenity Walk off Collier Blvd (approx. midway between the I-75 and Tamiami Trail intersections). This small park has been reliable for Brown-headed Nuthatch which never fail to both amuse and delight in equal measure:

Brown-headed Nuthatch seen at Serenity Walk

This is our (as in SW Florida's) only species of nuthatch with neither White-breasted nor Red-breasted Nuthatch ranging this far South.

Also seen in the vicinity were Downy and Red-bellied Woodpeckers. While any sighting of the Red-bellied Woodpeckers is unlikely to take the Birding listservers by storm, still, it is, nonetheless, a striking woodpecker with a bright red head and strongly barred back -- a description that surely beggars the accuracy of its moniker.

Red-bellied Woodpecker seen at Serenity Walk

Diversity, it is said, is the spice of life and perhaps nowhere does this adage hold truer than in the digital pursuit of plumes.

Tuesday, August 12, 2014

Hudsonian Whimbrel, Red Knot and Marbled Godwit at Little Estero Lagoon

[Little Estero Lagoon, Ft. Myers, FL. August 2014]

It's early August in Southwest Florida and shorebird migration is underway. A deluge of 7 inches of rain in one day in the area helps augment the naturally occurring tidal pond at the beach. This freshwater also contributes to the growth of vegetation in the sand and also attracts a variety of shorebirds at Little Estero Critical Wildlife Area (aka Little Estero Lagoon). Including such species as:
  • Hudsonian Whimbrel
  • Red Knot
  • Marbled Godwit
  • Roseate Spoonbill
  • American Oystercatcher
  • White Ibis
  • Black Skimmer
  • Least Sandpiper, Western Sandpiper, and Semipalmated Sandpiper
We start with the curlew:

Whimbrel seen at Little Estero Lagoon CWA
Whimbrel seen at Little Estero Lagoon CWA

One of four subspecies of Whimbrel worldwide, the Hudsonian is found exclusively in the Americas. As its name suggests, it breeds around Hudson Bay and other areas in the Arctic and winters in South America.

Whimbrel seen at Little Estero Lagoon CWA

So long as it's not snoozing with its bill hidden, the Whimbrel is straightforward to identify. Look for a large sandpiper with a downcurved bill. The crown is distinctive with a white stripe down the middle.

Whimbrel seen at Little Estero Lagoon CWA

The barring pattern on this large shorebird is striking -- and even more so on the underwing (as above).

Unlike the Hudsonian Whimbrel, the  Red Knot is not strictly just a passage migrant -- while some will journey all the way to the tip of South America, others will winter right here in Florida.

Red Knot seen at Little Estero Lagoon CWA

Red Knot seen at Little Estero Lagoon CWA

Many Red Knots were showing vestiges of their alternate plumage as was this Marbled Godwit still showing some barring on its breast.

Marbled Godwit seen at Little Estero Lagoon CWA

Marbled Godwit seen at Little Estero Lagoon CWA

Outmatching even the Godwit's impressive bill, the Roseate Spoonbill's is not only long but beautifully broad and rounded at the tip.

Roseate Spoonbill seen at Little Estero Lagoon CWA

Roseate Spoonbill seen at Little Estero Lagoon CWA

This has been a banner year for breeders at Little Estero. Annual breeders here are the Least Terns which were joined by Black Skimmers for the first time in 10 years. Unfortunately, the success of these species as well as the resident Wilson's and Snowy Plovers was not matched by the Oystercatchers. The pair that has nested here over the last 3 years, abandoned their nest after their eggs failed to hatch. Hopefully, they will try to nest again.

American Oystercatcher seen at Little Estero Lagoon CWA

Other birds included a rather stunned-looking White Ibis:

Matching the color scheme of the Oystercatcher were breeding Black Skimmers:

Black Skimmer seen at Little Estero

And the usual assortment of Peeps:

Least Sandpiper seen at Little Estero
This tiny sandpiper is straightforward to identify given its yellow legs and browner upperparts. However, the next two species can be confusing: Semipalmated and Western Sandpipers.

Semipalmated Sandpiper seen at Little Estero

Western Sandpiper seen at Little Estero

Unlike the Western peep, the Semipalmated is only a passage migrant. The two species are best told apart by the length and "degree of droop" of the bill with the Western's being longer and droopier.