Bird ID Request, Tarawa Atoll Pigeon (1 Viewer)

[Joe H]

I’ve attached some pictures of two pigeons I photographed on Tarawa Atoll, part of the Republic of Kiribati (the area was formerly the Gilbert Islands) back in August of 2009. For the longest time I assumed they were Pacific Imperial Pigeons (Ducula pacifica), but recently I’ve been cleaning up my life list and I see that my old copy of “A Field Guide to the Birds of Hawaii and the Tropical Pacific,” (Princeton University Press, by Pratt, Bruner and Berrett) does not have that species listed in the Gilbert Islands. Instead, it lists the Micronesian Imperial Pigeon (Ducula ociana) as a resident species.

There is also a web site that also identifies a small population of the Micronesian version on Tarawa:

Micronesian Imperial-pigeon (Ducula oceanica) - BirdLife species factsheet

“On Majuro Atoll in the Marshall Islands, a recovery programme led to an increase in numbers to c.80 individuals across 27 islets with a combined area of 5.2km2 (M. O'Brien in litt. 2011). The 2020 population is placed in the band 80 - 150 individuals. The populations on Lae, Lib and Namdrik, if still extant, must be small, as must the population on Tarawa; each is assumed to have a populations of no more than 50 individuals.”

But of course the internet giveth, and the internet taketh away...

Wikipedia has this: The Pacific imperial pigeon (Ducula pacifica) is a widespread species of pigeon in the family Columbidae. It is found in American Samoa, the Cook Islands, the smaller islands of eastern Fiji, Kiribati, Niue, the smaller satellite islands of Papua New Guinea, Samoa, Solomon Islands, Tokelau, Tonga, Tuvalu, Vanuatu, and Wallis and Futuna Islands.

So bottom line, I’m hoping someone more familiar with imperial pigeons, or the Central/South Pacific Islands can help me sort out the most likely suspects. I believe the two birds are the same species (an adult and a young bird) and are probably, in order of likelihood:

1. Pacific Imperial Pigeon (Ducula pacifica), largely based on the bill lump and lack of rust color on the body.

2. Micronesian Imperial Pigeon (Ducula ociana). Note, I didn’t photograph a lot of these birds as they were often seen and to me (at the time) not confusable with any other species. I don’t recall ever seeing a rust colored belly or breast, only the vent area. Most of the pictures I’ve seen of the Micronesian have the rusty color coming up from the vent area much higher up the body.

3. Island Imperial Pigeon (Ducula pistrinaria). It seems unlikely the bird in picture 1 would be a different species from the second bird in pictures 2, 3 and 4.

Many thanks in advance to anyone who can help me clear this up.

 

[DMW]

I have no experience with the relevant species, but to me these are almost certainly Pacific Imps. Island can be excluded as it lacks a bill knob, which leaves a choice between Pimp and Micronesian. As you say, the restriction of rufous to the vent seemingly excludes Micronesian, unless there is an obscure subspecies of Micronesian in Kiribati which closely resembles Pimp.

There's also an illustrated guide to Kiribati birds which describes Pacific as common on Tarawa Birds of Kiribati : a pocket guide to the birds of Kiribati | Pacific Environment

Whether the population of Micronesian Imp referred to by Birdlife is based on a misidentification, or both species really do occur, I couldn't say.

 

[Joe H]

That's a brilliant pocket guide, DMW! I wish I'd had it back when I traveled to Tarawa. I'll use it to look at some of the other photos I have. Thank you for posting it, and thank you also for your insight regarding the identification. I'm ready to put this ID to bed. There may well be a small population of Micronesian Imp someplace in Kiribati (they even had a postage stamp with a Micronesian on it), but I'm comfortable that the pigeons I saw on Tarawa were Pacific. Thanks again for the help and the link to the pocket guide!