Monday, July 25, 2011
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Solution by Tony Leukering
The flock of herons in this week's quiz photo are obviously poorly lit -- perhaps due to the lateness of the day, though the upperparts of various of the individuals are well-lit enough that we might take the apparent dark color as representing reality, particularly the lead bird in the bottom row. There also appears to be little or no difference in structure across the flock, so we might be dealing with only one species. In addition to the overall darkness of the upperparts of various of the birds, the first and last birds of the five in the bottom row show a distinct lack of coverts-remiges contrast, suggesting that our birds are not very poorly-lit Great Blue Herons showing no paleness on the head. That is because that species shows strong contrast between its blackish remiges and medium blue-gray median and lesser coverts, as does Gray Heron. Additionally, the long-necked Ardea herons have a distinct and obvious bulge hanging below the front of the body, which is the coiled neck -- much like that of Great Egret and different from all the medium-sized herons, with Reddish Egret being somewhat intermediate in this respect. However, given the uniformity of size and shape in the flock and the near-lack of any dangling of neck in some of the birds, Reddish Egret is probably also ruled out. The legs are simply too long for these birds to be Green Herons or any species of night-heron.
The above should mean that we have our solution, but let's deal with a few plumage and soft-parts color aspects. Reddish Egret has medium-toned plumage on the head and neck, pale facial skin, and a pale basal half or so to the bill, the last contrasting with a distinctly black bill tip. Our quiz birds show neither the neck/body color-tone contrast, nor the one on the bill. The bellies are obviously not white, nor are the chins, ruling out Tricolored Heron and Western Reef-Heron, respectively. Additionally, there is no underwing contrast that is so typical of Tricolored Heron. Finally, the middle bird of the left column of three and the one immediately behind it both have a strong suggestion of blue on the front of the head, either the facial skin or the base of the bill , and that provides any final clincher that we might need. Rachel Hopper took this picture of 12 adult Little Blue Herons at Tulum, Quintana Roo (keen-tah-nah row-oh), Mexico, on 11 March 2011.
Three respondents provided answers in the plural form: "___ Herons." Since official names of species are not plural (except for things like 'yellowlegs'), the two responses with the correct species were precluded from being correct for the competition; the other response presented an incorrect species.
Incorrect species provided as answers:
Green Heron - 1
Great Blue Heron - 2
Reddish Egret - 1
Congratulations to the 16 of 20 getting the quiz correct:
Answer: Little Blue Heron