Tuesday, May 29, 2012
The shallow waters along the shoreline of the bay also make it precarious for large boats that meander into the area. Case in point, the sailboat "Second Wind" somehow became grounded in these shallow waters several weeks ago. From the last time I saw it, it had been pushed further into the shallows, and now sits right up against the shoreline where it will remain indefinitely.
Sunday, May 27, 2012
I paddled closer and headed toward a good light as the bird seemed content to stay in a small area between two mangroves. I approached within 100 ft in the shallow water and waited for a nice pose. Snap, snap, a couple shots were taken. At first, I thought it was a juvenile little blue heron or maybe a snowy egret. But the bird appeared odd, not quite having the body shape or the slender beak of a little blue or snowy. No, something was quite different about this bird. After the initial shot, I examined the photo in zoom on the LCD and lo and behold, the white feathered bird had flaming red eyes.
Thursday, May 24, 2012
Tuesday, May 22, 2012
I think that feeding the chicks is the most difficult and energy-requiring task of the adult parent. Having seen many great egret chick feedings, it can also be concluded that it is risky and can cause significant injury to both chick and parent. Upon closer inspection of photos, one can see peck wounds along the beaks of adults and chicks. And no wonder, the great white egret beak is a weapon.
With more than one chick to feed, there is a constant battle. I learned that birds secret the hormone corticosterone (a stress hormone) that stimulates begging (most likely it stimulates hunger), which in turn increases parent provisioning (obesity in humans is correlated with cortisol levels, I wonder if there is a connection). Nevertheless, the success of feeding depends not only on prey density but also on this hormone. One chick often dominates and is fed more successfully than the smaller sibling(s). The parent flies in and does not begin the feeding right away. Rather, the adult will stand over the chicks that are begging and jutting their necks upward toward the adult's face. The adult stands erect and it is as if it is teasing the little ones that are working hard to get closer to the adult's beak. A chick will finally reach the adult's beak and within a split second, the adult is pulled downward with chick attached, beak to beak. The second or third chick will attempt to get in there and as seen in the photo below, both are clamped onto the adult while regurgitated food is transferred to the chick.
After about a minute of this, the adult will pull away and resume its erect position. Mean time, the siblings squabble and then commence with the begging. The process repeats itself a few times before the parent has enough and flies off leaving the little beggers behind.
Pelican feeding does not appear as violent. Instead, the chick can place its entire head into the adult's poach. Below are two photos of a rather large juvenile getting fed by its parent. It looked as if the chick did not have any siblings. This is a good thing for the chick because without competition, it will receive all the food and learning opportunities from the parent. Bon Apetit, petit oiseau!
Thursday, May 17, 2012
Because of lighting and wind protection, I have a narrow range from which I can photograph the bird activity. The highest concentration of brown pelican nests are located on the periphery of the island cluster that serves as the rookery. Although the pelicans can be photographed in good morning light, it is the exposure to the open bay that makes it difficult to photograph them. And during my most recent visit, there were strong easterly winds. Despite that, I gave it a try before the winds increased. The concentrated pelican nest site is noticeable from a distance as I crossed the bay. In the early morning hours before the sun burns high above, the adult pelicans (and 1-2 yr old juveniles) are busy flying to and from the island. The morning light on their brown wings is quite beautiful. I love their landing and take-off wing patterns and can spend long periods of time attempting pelican flight shots.
As I paddled toward the island, I could not resist the temptation to photograph the pelicans, but in less than ideal conditions. In early light (around 7 am), a high noisy ISO (had it at 1600 at one point) is required to keep the shutter speed reasonably high (1/640 is the slowest acceptable which incurs a nice wing tip blur). But with my boat being broadsided by the winds, a sharp image was unlikely. Consequently, these photos are for journal purpose only.
I moved over to the more protected area where I spend 90% of my time while at the rookery. From this vantage point, I can observe several great egret nests. There was one couple that appeared to not have any chicks and may still have eggs incubating. Something was going on because one of the adults was frequently bringing in twigs. This particular nest was located in the best light, so consequently, they were the highlight of the day. Other nests around them clearly had chicks, some of them close to adult size.
During this visit, I had few ideal opportunities to photograph the egrets. From my vantage point, I had rookery islands surrounding me, but only a relatively small portion of it located in the best light. As I sat in my canoe and waited for some action in the good light, lots of activity was going on to my right in a side light that shadowed the white birds. Most of the time, I sat waiting for that perfect shot that would take advantage of the warm morning light hitting the white feathers directly. This is most ideal with an easterly wind so that the birds display their beautiful wing spans as they land. Consequently, there are few photos in this collection illustrating the hustle and bustle of the egret and pelican rookery.
Tuesday, May 15, 2012
The report found high mercury levels in these birds, especially during excellent breeding season. The great egret experiences the brunt of it, while the "lower trophic level generalist" white ibis does not consume much mercury. However, in the great egret chick, most of the mercury gets routed into the growing wings. This might be because feathers represent the majority of growth in the nestling. Once fully grown, feathers lose their blood vessels and so whatever mercury is in the feathers will stay in the feathers. Because of this, the chicks are buffered from the poison. In fact, bird feathers are used as indicators of heavy metal pollution. So the good news from the report is that the mercury does not have a negative impact on these birds, at least in the short term.
At the rookery this past weekend, I watched several great egret and brown pelican chicks exercise their not-yet-fully-grown wings. Upon examining the photos, you can surmise that stages of growth that occurs. The feathers, which are nothing more than extensions of the skin are comprised of remiges and coverts. Remiges are the large flight feathers that we love to photograph so much. These are often referred to as primaries (the outer wings) and secondaries (inner wings). The coverts are smaller, closer to the bird's torso and form an outer layer of insulation. When you look at the nestlings wings, you can see that the coverts are not formed yet, leaving the remiges exposed. The underside of the great egret wings look more like skin than feather.
The first two photos below are egret nestlings. The first was shot this past weekend and clearly shows the lack of covert feathers on the bird. The second photo was shot approximately 1 year ago. You can see that this bird's feathers are more developed and appear more adult-like. The third photo shows an adult.
Not to forget the brown pelican, the nestlings are also working hard to spread their wings. The first photo shows a juvenile that is close to fledging. The second photo includes two juveniles at different stages; one not yet able to leave the nest and the about-to-fledge juvenile. Notice the adult hunkered in its nest. The third photo again demonstrates a young nestling exercising its small wings. Compared to the first photo, this baby has a ways to go!
Monday, May 7, 2012
Nevertheless, I keep trying and in the meantime, here are a few different poses of the nesting cattle egret, including one juvenile. None of these is "that shot" but they at least illustrate the busy life of a nesting cattle egret.