# The Auk/13/1/The Standing of Ardetta neoxena

A. Hoen & Co. Lithocaustic, Balitmore
ARDETTA NEOXENA CORY
THE STANDING OF ARDETTA NEOXENA
by Frank M. Chapman
Plate I.
Certain facts in the history of this well-named Bittern have caused several writers, myself among the number, to speak of it as probably an aberrant form or color-phase of our widely distributed Ardetta exilis. In figuring this peculiar bird in 'The Auk' an attempt has therefore been made to bring together for direct comparison as many of the known specimens as were available, for the purpose of deciding if possible the bird's standing.
Described by Mr. Cory in 1886 from a specimen taken in the Okeechobee region of Florida, there have since been captured thirteen additional specimens. Of this number five are from the type locality in Florida, one is from Michigan, and seven are from Toronto. Through the generosity of the owners of these rare birds I now have before me ten of the fourteen recorded specimens. This series presents much variation, to be spoken of more particularly after comparing the apparently normal plumage of the adult male and female and immature male with the corresponding plumages of Ardetta exilis.
| Ardetta neoxena, ♂ ad. | Ardetta elixis, ♂ ad. |
| Crown glossy black. | Crown glossy black. |
| Back of the neck glossy black. | Back of the neck chestnut rufous. |
| Interscapulars entirely glossy black without buffy margins. | Interscapulars glossy black, outer edge of outer ones margined with buffy white. |
| Tail glossy black. | Tail glossy black. |
| Front of the neck chestnut. | Front of the neck white more or less washed with buffy |
| Abdomen, sides, and tibiæ mixed chestnut, black, and smoky brown. | Abdomen, sides, and tibiæ white more or less washed with buffy. |
| Under tail-coverts glossy black. | Under tail-coverts white slightly tinged with buffy. |
| Primaries slate gray without cinnamon rufous tips. | Primaries slate gray, the outer ones sometimes, the inner ones always tipped with dull cinnamon rufous. |
| Outer secondaries slate gray without cinnamon rufous tips; inner secondaries black, glossy on the outer web and without chestnut rufous. | Outer secondaries slate gray tipped with cinnamon rufous; inner secondaries with outer web chestnut rufous, inner web blackish slate gray. |
| Lesser wing-coverts at bend of wing black. | Lesser wing-coverts at bend of wing chestnut rufous. |
| Median wing-coverts chestnut. | Median wing-coverts cream buff. |
| Greater wing-coverts blackish slate gray, the inner ones with chestnut tips. | Greater wing-coverts with basal half slate gray, terminal half chestnut rufous, the inner ones washed with cream-buff on the outer vane. |
| Under wing-coverts chestnut. | Under wing-coverts white, grayer at the base, and washed with buffy. |
It will be seen from this comparison that there is no regularity in the substitution of colors; hence these birds differ not alone in color, but also in pattern of coloration. Thus, the chestnut of neoxena may replace either the white or buff of exilis, or the former may be black where the latter is chestnut rufous, buff, or white. The differences in distribution of color, or relative markings of the same parts, are most marked in the interscapulars, under tail-coverts, greater wing-coverts, and tips of the quills.
| Ardetta neoxena, ♀ ad. | Ardetta elixis, ♀ ad. |
| Similar to male but crown slightly, and back decidedly duller. | Similar to male but black of head tinged with brown; back rich, dark brown; interscapulars more widely margined with buffy; under parts more heavily washed with buff, and with numerous blackish shaft-streaks, and in places slight blackish mottlings. |
Measurements.
| Six adults (5 males and 1 female, 4 from Florida and 2 from Toronto) average: wing, 4.59; tail, 1.56; tarsus, 1.56; culmen, 1.76 | Six adults (4 males and 2 females, 3 from Florida and 3 from Erie, Pa.) average: wing, 4.60; tail, 1.59; tarsus, 1.59; culmen, 1.81. |
My notes on the female of neoxena are based on the original records and Mr. Hubert Brown's comparison of the two adult Toronto females, neither of which I have seen. One of these ​has been compared by Mr. Brewster with a bird (No. 44,087) in his collection, and which he has loaned me. Mr. Brewster remarks: "The Toronto bird is a trifle the darker on the back and the chestnut of its under parts is slightly richer, but in other respects the two specimens are almost exactly alike." This No. 44,087 is not sexed, but with little doubt is an adult female. The outer margins of the interscapulars are decidedly brownish, but whether this marking appears in the two Toronto birds is not stated.
It appears, therefore, that there is less sexual difference in neoxena than in exilis. In size the two birds agree.
| Ardetta neoxena, ♂ immature | Ardetta elixis, ♂ immature |
| Similar to adult male but black of the head and back somewhat duller, the outer margins of the interscapulars slightly tinged with chestnut. | Similar to adult male but crown duller, the feathers margined with chestnut rufous; back slate gray or blackish slate gray, the feathers tipped with chestnut rufous and ochraceous buff; under parts more heavily washed with buff, and with numerous blackish shaft-streaks. |
Four of the ten specimens of neoxena now in my possession are birds of the year, three of them still showing remains of the nestling plumage. This is especially marked in a male from Toronto (Aug. 24, J. H. Ames) in which the nestling plumage still covers the abdominal region while the feathers of the head and back, although fully grown, still have the downy neossoptiles attached to their tips. These specimens are of the utmost importance for they evidently show that the immature plumage of neoxena, or the first plumage succeeding the nestling down, is practically like that of the adult, while exilis, on the contrary, at this age, differs markedly from the adult.
Here also should be mentioned the notes of Mr. J. F. Menge on the nest and young of neoxena, as quoted by Mr. W. E. D. Scott. Mr. Menge, who collected four of the six Florida specimens, writes as follows: "I herewith send you notes concerning the Bittern as requested by Mr. J. W. Atkins, first found on 8th ​of June, 1890, two and a half miles above Fort Thompson, Florida, in a small willow swamp on the borders of Lake Flint [lege Flirt]. It was built of willow twigs and lined inside with maiden cane leaves. It was in a low bush two feet and a half above the surface of the water. There were four young birds, about two-thirds grown, in the nest. I had one of the old birds in my hand, which I think was the female. She was not inclined to fight and would not leave the nest. The other old bird was two or three feet from me and seemed a much larger bird. I did not disturb them and when I let the old bird go she hopped back on her nest as though she was accustomed to being handled."
This comparison shows such striking differences between these two birds, that to give further reasons for regarding them as specifically distinct seems much like proving an axiom.
Aside from the differences in color and pattern of coloration and the manner in which the mature plumage is acquired, the fact that the young of neoxena resemble the adults, and that no example of exilis showing an approach to neoxena has ever been recorded, would seem to give Cory's Bittern undisputed title to full specific rank.
While we may therefore reject the suggestion that neoxena is a color-phase of exilis, and in fact leave exilis entirely out of the question, the specimens of neoxena present certain characters which demand investigation. Allowing for normal variation only three of my ten specimens of neoxena are alike, while the remaining seven show either melanistic or albinistic markings or both combined. No. 167 (♂ im., Mich.) has several white feathers on the right tibia but is otherwise normal. The type (No. 2001, Fla.) has two entirely white feathers on the right flank. No. 44,087 (Fla.) has the abdominal region and flanks wholly chestnut without black. There are three pure white feathers on one side of the belly and five on the other; part of the anterior portion and the entire inside of the right tibia are white. No. 7 1 (♂ ad., Toronto) has conspicuous white patches on the abdomen, vent, and tibiæ. No. 44,088 (im., Fla.) presents the extreme of albinism; the abdominal region, breast, and tibiæ; are almost wholly white, the outer primary of the left wing is entirely white, and white feathers appear on the bend of both wings and under wing-coverts. No. ​29,289 has the abdominal region and breast black slightly tinged with chestnut and with one or two white feathers on either side of the belly. The left tibia (the skin on the right is wanting) is chestnut and black with white filoplumes. The chestnut on the median coverts is much reduced. No. 44,086 (♂, Fla.) is almost completely melanistic. The abdominal region is wholly black with the exception of two pure white feathers on either side of the belly. The tibiæ are smoky brown the inner side of the right one being white. The foreneck is black washed with dull chestnut, the wing-coverts are glossy black with no trace of chestnut.
This remarkable variability will be more fully appreciated by an examination of the following table:—
that neoxena is a color-phase of exilis. Only three of the fourteen known specimens depart widely from what is evidently the type of coloration, and in every instance these differences are clue to albinism or melanism, not one of the specimens showing any approach to exilis. Nor do the known cases of dichromatism among Herons give us any ground for asserting that neoxena is a dichromatic phase of exilis. Aside from the important differ- ences exhibited by the young and female, a careful comparison of the adult males shows no substitution of colors such as we find in the phases of Ardea rufescens, Megascops, Fulmarus, or even Stercorarius. This is especially marked in the under parts, which in exilis are essentially all buffy, while neoxena has a chestnut forneck, a chestnut and black belly, and, in every instance, jet black under tail-coverts.
It is natural that the variability of neoxena should cause us to regard it with suspicion, but beyond the fact that the two birds are generically related and of the same size, there is not one grain of evidence implicating exilis. This latter bird is represented in our collections by hundreds of specimens not one of which has given reason for believing the species is dichromatic.
For the loan of specimens of this rare bird I desire to heartily thank Messrs. William Brewster, J. H. Ames, Charles B. Cory, J. H. Fleming, Jas. R. Thurston, and L. W. Watkins.
BIBLIOGRAPHY.
* ↑ A fifteenth specimen, from Wisconsin, is recorded beyond in this number of 'The Auk'
* ↑ Auk, VIII, 1891, 309.
* ↑ Not examined.