Egret colony

[secret] Egret colony (See full article and images Australian Wildlife Secrets Volume 2 no 3)

John Cooper

 

While lugging my heavy equipment across the maze of levees, my thoughts wandered to the previous year when I first photographed this large egret colony sprawled out before me. On that occasion the area was free of agriculture crops, allowing vehicle access right up to the very perimeter of the nesting sites. Since then, however, the landscape has undergone a marked transformation and the colony is now completely surrounded by lush green rice fields and their associated embankments.

            The nesting site is an old stand of Black Box and Belah trees on the outskirts of Leeton in southwestern New South Wales, the heart of the rice-growing industry in the Murrumbidgee Irrigation Area. Great, Intermediate, Little and Cattle egrets nest here annually, with a scattering of Sacred Ibis and Little Pied Cormorants.

            A survey of nest numbers in January 1997 by Keith Hutton and Mike Schultz of the Murrumbidgee Field Naturalists Group recorded 591 Intermediate (Plumed) Egret, 98 Great Egret, 67 Cattle Egret, 7 Little Egret, 33 Sacred Ibis and 4 Little Pied Cormorant nests. Keith commented that this was a fairly conservative estimate, with the total umber of nests being closer to 1000.

            The prolonged drought from 2001, though, resulted in severe reductions in the breeding of all species at this egret colony. In the last season before the drought-breaking rains came in January 2010 there was only 1 Intermediate Egret, 3 Eastern Great Egret, 9 Cattle Egret nests, and no others. This improved following the wet autumn and winter of 2010, when 60 Intermediate Egret, 140 Eastern Great Egret, 10 Cattle Egret, 1 Little Egret, 8 Australian White Ibis and 1 Little Pied Cormorant nests in the colony were recorded in January 2011.

It is of interest, too, that only 710 hectares of rice was harvested in the area from 11 farms in the worst year of the drought in the 2008 crop; this recovered in 2011 to around 30,000 hectares on 421 farms. So there are huge variations in breeding numbers of these species in the region, dependent on water availability.

Colonial nesters, in particular, are very sensitive to disturbance, so selecting a nest to photograph on the outer perimeter of the colony was necessary. The nest I finally chose was home to a family of Intermediate egrets (Ardea intermedia) and sat at an approximate height of 5 m. It contained chicks around 10–14 days old, too young to be spooked by any activity near the nesting site.

I erected a 5-m tower with a hide on top about 7 m from the nesting site. After securing the tower with steel guy ropes I retreated to a safe distance to observe the parent birds’ reactions. In less than 10 minutes one of the parents returned to the nest, unperturbed by this new intrusion, which is always very reassuring. I then left the area for a couple of days, coming back to do my photographic sessions after the birds had settled back into their routines.

            As I approached at dawn on the third day the sun sat like an orange ball on the horizon, casting long shadows across a green landscape and highlighting the white egrets in the colony. Some were sitting on eggs, while others stood guard over young chicks waiting for their mates to return from early morning foraging. The rice fields provide a rich banquet of aquatic life, which no doubt is the main attraction for the annual nesting here.

            As I made my way up the tower with a backpack laden with photographic gear, the parent bird on sentry duty flew gracefully overhead, its nuptial plumes glowing in the early morning sun as it alighted in a nearby tree. Within minutes my camera was set up on a tripod and once I ceased to move around in the hide the parent bird alighted back onto the nest. The image of this egret family through the camera viewfinder was sheer magic and I knew that more than one roll of film would be exposed that morning!

            The feeding of the young was infrequent, averaging every 3 to 4 hours between feeds. Once the mate finally returned from foraging there would be a brief but animated greeting, with both parent birds displaying their beautiful plumes to one another, while at the same time bobbing up and down. Meanwhile, the chicks with outstretched necks and gaping mouths demanded to be fed.

            The parent who had been on sentry duty would then immediately depart the nest to search the fields while the other regurgitated a copious quantity of fish and invertebrates. If there was any delay in the parent coughing up, the chicks would stimulate the process of regurgitation by seizing the parent’s bill crossways and hanging on. After feeding, parents and chicks alike would spend considerable time preening and sleeping.

After several days photographing I made the four-hour return trip home to Cowra with the intention of returning in approximately two weeks’ time, when the chicks would be more advanced. This particular egret colony is on dry land, but on my return visit I was surprised to find many of the trees now standing in water. A heavy storm a day earlier, and leakage of water from the levee banks, had contributed to this minor flooding. Fortunately, my tower was still standing on dry land.

            As I approached the tower I was aware of an increased number of dead chicks strewn about on the ground, no doubt victims of the storm and high winds. Several resident Black Kites were doing their bit to clean up the carcasses. It wasn’t until I was back in the hide and looked out the side window that I noticed that one of the Black Box trees had been uprooted and fallen over, the outer branches just touching one of my guy ropes.

I counted six empty nests in this fallen tree, the contents of which had been propelled to the ground. Suddenly I got a glimpse of a very young chick, which appeared to be approximately 2 to 3 weeks old, wandering aimlessly through the branches, apparently the sole survivor. What I was about to witness I found most extraordinary, though not unique (see information box below).

            Two adult Intermediate egrets alighted on the branch next to the young chick. One of the adults, I presumed the male, carried a stick in his bill which he in turn presented to the female. She accepted the stick but looked somewhat bewildered as to what was expected of her and so dropped it! The male then returned from the ground with another stick but this time proceeded to place his stick beneath the chick, which was standing at a fork in the branch.

            Following the male’s lead, the female returned with a stick and added it to the first. This process continued until the chick was well supported on a makeshift platform, and from there the adult birds fed it and provided it with sheltered from the midday sun.

            Although these activities distracted me from my photographic assignment, I felt privileged to have witnessed these devoted parents caring for their sole remaining chick in this way. When I finally left the site, the activity at the new nest was identical to that in the numerous other ones around it, and there seemed no doubt that this chick would be raised to maturity.

 

<<Box>>

<<box head>>Breeding behaviour of egrets

Some egrets have been recorded rebuilding their nests following mishap, and it is not uncommon for them to add sticks to their nests at various stages during the breeding cycle. The Egret Watch Program, which has colour-banded and tagged egrets throughout New South Wales for many years, frequently records the continued feeding of young away from the original nest site. Fledged Little egrets have been observed pursuing their parents on wing to be eventually fed. Cattle Egret chicks have been recorded clambering on top of overturned nests, or shifting from their own nest to abandoned nests some distance away, and their parents continuing to feed them to fledging. Fledged Cattle egrets have been observed being fed at considerable distance from the original nest site, even on the ground, where they survived for at least 6 weeks after falling from the nest.

Following major storms at Seaham Reserve near Maitland, NSW, Cattle egrets have twice been observed rebuilding a makeshift nest beneath a sole surviving chick following the loss of the original nest. In one of these observations (January 1992), the nest was observed until the chick fledged.

The stranded chick that I saw at Leeton may have been the offspring of the attending adult birds or they may have adopted it. Adult Cattle egrets have once been observed caring for young (8 to 10 days old) ‘foster’ chicks, which mysteriously appeared in a marked nest, possibly having fallen from a higher nest.