We recently visited Green Cay Wetlands in Boynton Beach, Palm Beach County, Florida. This is the nature center and the beginning of one loop of the well-maintained boardwalk. As we walked a mile and a half along the boardwalk, a Northern Harrier made several passes over the area, but I failed to get very good images. Then, just before we departed, it flew right towards us, into the wind.
The harrier performed a series of low-level stalling maneuvers-- gliding upward and then suddenly falling almost to the ground before it regained lift.
Since the harrier glides with its wings configured in a strong dihedral angle (V-shape), it can safely regain lift at slow speeds because only one wing stalls at a time. The high dihedral angle increases the rolling motion of the bird, so the opposite wing quickly regains lift, restoring stability. Turkey Vultures, Golden Eagles, and many seabirds also position their wings in this manner as it permits much greater stability in slow low-level flight. The alternating stall and recovery of each wing causes the vulture's wings to tilt back and forth while it sails.
For the past few weeks it has been relatively quiet on our local south Florida birding patch. Numbers and varieties of birds have decreased for several reasons. The rainy season extended into November, maintaining high water levels in the wetlands. This disperses prey species. Sight feeders such as herons and egrets are not concentrated in the canals. Mudflats are not yet exposed to attract sandpipers. Tactile feeders, including Wood Storks and ibises cannot forage effectively in water that is deeper than the length of their bills. This time of year, mud flats should be exposed along the edge of the lake. The prolonged high water levels have encouraged the accumulation of periphyton, an essential element of the food chain in the Everglades ecosystem. A complex mix of "algae, cyanobacteria, invertebrates. secretions, and detritus attached to submerged surfaces," periphyton serves as a food source for fish and invertebrates. It improves water quality by adding oxygen and recycling nutrients and nitrogen from agricultural pollutants. Read more about periphyton here. Note the mat of periphyton floating on the surface. The arrival of the Yellow-rumped Warblers signaled the end of warbler migration. Sparrows, goldfinches, waxwings and flocks of robins have not yet appeared, with a few exceptions. While they overwinter in our area, their local abundance varies greatly. Earlier this fall, we had brief visits by three sparrow species, but none chose to linger more than a day or two. I sighted a Lincoln's Sparrow only once, on October 16. Ten days later, two White-crowned Sparrows showed up and lingered for a week. Another one-day wonder was this Swamp Sparrow, on December 4. A single American Robin appeared on December 5. This is odd, as they usually arrive in large flocks more towards the middle of winter. Disturbance of the land has increased. As related earlier, we lost our "Fake Hammock" with its five mature Florida Trema trees due to vandalism and fire caused by the gang of off-road vehicle riders. In addition, a new roadway is being pushed through adjacent to the Yellow-crowned Night-Heron rookery. The rookery occupies the trees on the opposite side of this canal-- a peaceful enough scene, looking south, ... ...but the view from the same spot, looking north, reveals the construction. The noise and human activitiy caused by excavation and grading, milling and paving is having its toll on the rookery. Although the herons will not be courting and building their nests until late March, I often find a few roosting there all year 'round. Since construction started, I have twice seen one Black-crowned Night-Heron at the location, but only once this lone Yellow-crowned Night-Heron. It appears to be retching, perhaps attempting to disgorge some undigestible prey remains, but nothing ever came out of its mouth.. I stopped visiting the rookery area except for weekends, when the workers and machinery are inactive. A pair of crow-sized Pileated Woodpeckers still occupy the remnant of woodland that has not been killed by herbicides in preparation for the roadway extension. The male sports a red "mustache." He drummed atop a wooden utility pole, attracting the female. They provided me with some of my few flight shots of Pileated Woodpeckers. On these quiet days I tend to stay in one place, with the rising sun behind me, and allow the wildlife to reach a baseline state of equilibrium. A favorite spot is next to one of the few remaining fruiting Trema trees. On one occasion the loud and brief shriek of a Blue Jay broke the silence as other birds dove for cover. The cause of their distress was evident a second later as an immature Sharp-shinned Hawk flew in rapidly and perched right in front of me. A few days later, in the same tree, a Northern Flicker provided me with a very nice photo opportunity. A Gray Catbird perched nearby. In an adjacent exotic Brazilian Pepper tree, a Blue-gray Gnatcatcher eyed me. An immature Red-shouldered Hawk rested on the dried-out flower of a Royal Palm. From an upper branch, a male Boat-tailed Grackle's iridescent coat reflected all the colors of the rainbow. Just as the birding slowed down, the butterflies increased. I found two butterfly species that were new to my patch, the Common Buckeye... ... and a Silver-banded Hairstreak. Monarch butterflies are declining in number due to loss of habitat containing milkweed, host for their larvae. Their winter home in Mexico is also being destroyed. I could not resist this shot of one against the sky.
Birding is an exercise in statistics. Finding a certain bird depends upon the probability that the birder's path will intersect with that of the bird at a given moment in time. For more common birds, this probability is high because we are not looking for a single bird, but rather one that represents the species. A knowledge of birds' habits and habitats greatly increases the chance of a successful quest; the bank robber selects banks because "that's where the money is." Very few other birders visit our favorite birding patch, mostly because it is only accessible via private or posted land. Trails in the patch itself are open but there are restrictions against use of motorized vehicles, overnight camping and open fires. There are no Internet bulletins alerting us to unusual finds. Although we have seen some birds that are uncommon, we have reported only one or two truly unusual species from this location. We walk the same old local patch, morning after morning. Often we are there before the sun rises and may walk and watch for two or more hours. We see the same old resident birds, and the same old migrants visit or stay for the winter. Our expectations are not high. If we set out to see a specific less common species, more than likely we will fail in our quest. Yet we are open to discovery. We notice the incremental changes-- the rise and ebb of water levels in the wetlands, the flowering and the fruiting, destruction and sometimes restoration. We have grown accustomed to all the snags and rocks and shadows that look like distant birds and mammals, and we notice the new garbage bag or the out-of-place shadow that may be a fox, or a Bobcat. We are always alert for non-avian subjects. During the past seven years of walking this patch nearly every morning we have found 135 species of birds, recorded since 2009 in our eBird List of Species, West Miramar Water Conservation Area. Most of these we documented among over 5700 photographs on FLICKR for this site alone. Interestingly, some of these we have seen only once or twice. Despite our regular observations of this area, we have been there only a tiny fraction of all the daylight (and none of the nighttime) hours over the past nine years since first setting foot there. Statistically, our records are insignificant. How many birds have we missed just by minutes or days or years? On a still morning the slight rustling in a shrub, easy to overlook, revealed the first Orange-crowned Warbler we ever saw in the patch, though once we learned where to look for them we have seen several more. The stirring of a single blade of grass invited us to find our first Rough Green Snake, wet from the morning dew. It responded to my approach by retreating across a sandy patch and rearing up towards me like a tiny cobra. A flash of yellow color in the brush disappeared as suddenly as it appeared, and a lucky photo documented our first and only Yellow-breased Chat. Uncommon but not rare, our patch must have been visited by many more chats besides this one so fortuitously sighted. A shy and retiring Black-whiskered Vireo showed itself during only one of our hundreds of visits to this particular thicket. How many times had it been there when I was otherwise occupied? A dull-plumaged Bell's Vireo presented an identification challenge. We have seen it only twice, in October of 2009 and 2012. Short-tailed Hawks flew over only twice. This is the more common dark morph, seen this past October. I wonder how many I missed by not scrutinizing the vulture flocks which help disguise them from their usual prey of small birds. This dissimilar light morph was the first Short-tailed Hawk on my life list of species first seen (and photographed). A few more spectacular birds have shown up on only one occasion. They include a small flock of Roseate Spoonbills that appeared in late November, 2012 and stayed for three weeks. Remarkably, the spoonbills were joined by our first and only flock of White Pelicans, a species that also lingered for several days. Neither species has reappeared since. Reddish Egrets are rarely seen away from the coastal brackish waters, yet a single immature bird visited us,18 miles inland, and lingered for over a month. As is typical, it pranced about erratically in search of prey. The highlights among rare visitors were two Whooping Cranes, the first ever reported this far south in Florida. They were captive-reared in Wisconsin and released to migrate on their own. One injured its foot and had to be treated and rehabilitated and was released in Tennessee. The other lacked survival skills and was relocated to a ranch in central Florida. Sadly, both perished during the winter. If this video does not display, please visit this link: http://www.youtube.com/watch?v=FeKMkfJOlco&featu
After I captured these views of a Blue Jay busily foraging for acorns, I realized that I have far too few photos of this common yet beautiful bird. I caught this one in a baseline state. Several acorns can be stuffed into one gular pouch. Jays take up the highest perches, watching for intruders, ready to sound the alert. Blue Jays are so common that I don't feel an urge to photograph them, and when I do they seem to be smart and wary. Like the Steller's Jays in New Mexico, their shadows often fall on mine as they follow me with the sun at their backs. They like to keep some vegetation between them and the camera. Always on guard, Blue Jays are easily agitated, whether simply by my presence or because of some real or imagined threat. The excited call of one summons hordes that appear out of nowhere. Bellicose and unafraid, they mob or attack owls eagles, large hawks, some falcons as well as cats and anything smaller and weaker. I watched three jays chase a Merlin that could have killed any one of them. This American Kestrel was fair game. The kestrel retreats, but the chase is still not over. Loggerhead Shrikes may eat small birds, but they are no match for this scruffy jay in molt, who retained his perch as King of the Roost I obtained a rare intimate portrait.
