In the field, no two birders would identify a rare bird in facsimile fashion. It is especially true of the first deci-second of the encounter.
“What marker did you see first?” would invariably elicit fascinating answers from birders that have clapped eyes on a rarity, together as a group.
Take a birding episode from Sholinganallur two weeks ago, for how three birders responded to this question.
Members of Madras Naturalists Society (MNS), the three were part of a small group on a casual weekend jaunt to the birding site. They sighted five Gadwalls, two male and three female, at an unlikely waterbody, one sandwiched between tall and swanky office buildings at the Sholinganallur IT Special Economic Zone. To its north lies the Pallikaranai Marsh, within hearing distance of a dabbling-duck symphony. To its south lies the famous spit of land that is referred to as the Perumbakkam wetland, but is part of the Pallikaranai Marsh.
Now, on to the first markers their minds registered. Umesh Mani recalls that his eyes landed on a male Gadwall’s all-black bill. In the same sweep of the eye, he noticed that there was “no white line running across the eye and down the nape”. Taking in these facts, his mind instantaneously registered that it was not a Gargany, and that there was a Gadwall out there. Chandrasekar Sundaram first saw the same male Gadwall’s greyish colour, and it was the black rump that settled the question for him.
A male Gadwall at Sholinganallur IT-SEZ. Photo: Chandrashekar Sundaram
Gnanaskandan Keshavabharathi saw the orange bill of a female Gadwall, paddling not too far away from this male, and he had found his bird. As he would explain later, Gnanaskandan had in fact had his eyes peeled for Gadwalls during the visit. He was specifically looking for the orange bill of a female Gadwall, while scanning a flock of Wigeons.
“To be honest, when we were talking at that point, Gnanaskandan is the one who spotted it first, identifying a female Gadwall by the orange bill. And then we were certain by looking for the features in a male Gadwall,” says Umesh.
Various markers
“Supposing there is only a mixed flock of female ducks — many a time, that happens, right? — you would have to look for differentiators between female ducks from different species. A birder has to know what to look for. When it is just female ducks, you need to have a separate set of features to look for.”
In their usual plumage, which they may carry well into their wintering grounds, male ducks are easier to differentiate from other duck species. However, adult males would go through what is called eclipse plumage after the breeding season. During this period, they would resemble the female of their own species. Fortunately, this period is short, and usually, the adult male duck would easily recognisable. Adult male ducks would be largely be wearing their usual, colourful finery even in the wintering, non-breeding grounds. However, when a male sub-adult duck transforms into an adult, things can get really confusing.
“The plumage that sub-adult male ducks wear during their transition to adulthood not only make them resemble the female of the species, but also set them up for being mistaken for some other duck species,” explains Gnanaskandan.
“Sub-adult Northern Pintail males that are in this ‘transformative plumage’ — which is still known as eclipse plumage — will also wear a grey similar to the Gadwall male’s. In these circumstances, you have to look at the bill shape. Consciously, I have been looking for the bill. Just like that, we caught sight of a female, and then a male. Then, on the other side of the waterbody, we saw one more male and two female gadwalls,” says Gnanaskandan.
Wigeon flocks
There was a huge flock of Wigeons, and these Gadwalls were not too far removed from them, strengthening an already well-entrenched idea that a very small number of Gadwalls can be expected to arrive even in a place not known to draw Gadwalls, as long as it is known to play host to Wigeons.
Gadwall sightings remain an extremely rare occurrence in Chennai, and birders in the metro hold to this view. Observations from elsewhere also support it.
A female Gadwall Photo: Umesh Mani
Having lived in Hyderabad, Umesh points out that in waterbodies there, he had seen Gadwalls with Wigeons. Gadwall sightings are rare in Hyderabad too, but not as rare as in Chennai, adds Umesh.
“It helps to know which ducks Gadwalls associate with. So, when you see these ducks, you should look for Gadwalls. When you know they are seen with Wigeons, ideally, when you see a Wigeon, you should also look for a Gadwall. It is quite likely they are also there,” Umesh makes it clear.
While admitting that there is no clear-cut explanation for why Gadwalls are found around Wigeons, Gnanaskandan draws attention to the fact that they are both of the genus Mareca .
He echoes the view that a few Gadwalls could be migrating along with a large Wigeon flock, to southern parts of the country, certainly not seen as the Gadwall’s favoured wintering pit-stop. Gadwalls are found in greater numbers in certain northern sections of India during winter.
The possibilities
Responding to a question about Gadwalls and Wigeons, ornithologist V. Shantaram says, “They might have travelled together? We still do not have that kind of study in India to tell how they travel, but it is still possible that they may associate with each other for a longer period than they would with any other species. They either travelled together, or found affinity with each other after arriving here.”
Shantaram also underlines that association could spring out of necessity and convenience: “If you went into the forest, you would see what is known as mixed hunting parties. Bird species may be coming together because they stand to benefit from the association. Or, it can also be coincidence. They do not need to be closely related. In fact, if they are, they need to be slightly away from each other, because they will be looking for similar kind of food.”
( ‘Migrant Watch’ is a column about birds that visit Chennai during winter)
