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The Great Potoo (Nyctibius grandis) finally confirmed for Belize

Jan Meerman

December 1, 2009

The Great Potoo, is wide ranging Neotropical Bird found from Southern Mexico into much of South America. Untill now, this was a species for which its status was unconfirmed in Belize. Jones (2003) in his “Birds of Belize” writes: “ Several reports, but none confirmed. Most, but perhaps not all, are likely misidentified Northern Potoos resulting from confusion with their respective vocalizations”.

On the night of September 29-30, 2009, around midnight , I got startled by a strange call (Green Hills Butterfly Ranch, Chiquibul Road, Cayo District, Belize, UTM E: 289900 N: 1891220 / 17°05’52.17”N, 88°58’26.60”W). After some searching I saw a large bird sitting on a dead snag next to the house which would produce the call at irregular intervals. The bird had large bright orange eye-shine, but would turn away its head once I put my flashlight on it. Initial thought was an owl. It was sitting very upright to the extent of leaning backward a little. The head was very large but through the binoculars, I couldn’t really see it well. As soon as I put a flashlight on the bird, it would turn its head. Also my position, looking from my veranda up to the bird which was sitting at least 15 m (50ft) above me did not allow for getting a good view of the head or ear-tufts should these have been present. The only thing, I thought I was able to see was a fairly pale breast with darker wings and a fairly long tail. There appeared to be some lighter spots on the backside. All of this was very vague; my flashlight was not that strong. Nevertheless it was obvious that this was a large bird. I estimated it to be at least 50 cm (20”) total length. In spite of the nocturnal conditions I took some pictures (Canon Powershot SX10-IS) using my flashlight as light source. One of these pictures ended up showing the outlines of the bird in some grainy detail.

As indicated, the call was most startling. Nothing like I recalled hearing before. It was quite loud, very “throaty”, and on occasion even human like. There was some variation. Mostly some drawn out “Kgroooooow”, repeated after a couple of seconds, occasionally a shorter “Wchow” , which was more human like, like someone hailing you from a distance. I am familiar with most calls of the Owls and Nightjars occurring in Belize and also I am familiar with the call of the Northern Potoo (Nyctibius jamaicensis). However, neither of their calls matched this one. Using the same digital camera I recorded a video file with attached sound file for about a minute. The sound came out quite audible although there is a lot of back ground noise from a very loud frog chorus.

The following day, some quick research online unearthed some internet sources with bird calls. The most useful was “Xeno-Canto” (http://www.xeno-canto.org/) and using that resource, the only match of the call that I found was from the Great Potoo.

Unfortunately, the bird did not return (or at least did not vocalize) in any of the nights following the observation.

In subsequent communications, Lee Jones, author of Birds of Belize, indicated that he suspected that the picture and calls indeed could be attributed to a Great Potoo, but that verification of the size and the call would be necessary to actually confirm this suspicion.

To verify the size of the bird I would have wanted to take measurements of the branch that the bird used as for perch. But this perch was a dead branch (lightning damage) in a more than 25 m (>85 ft) high Cedar (Cedrela odorata) tree and quite unreachable. Second option was to compare the bird with another bird of know size.

In my files I found a picture of a Plumbeous Kite (Ictinia plumbea) in the same tree and taken from exactly the same location. I overlaid a transparency of the Potoo picture over the Plumbeous Kite picture and got a near perfect match of the branches. See pictures below. Obviously there are some potential sources of error. The kite is a (fully grown, 3 weeks after leaving the nest) juvenile, so potentially somewhat smaller than an adult. The tail tip of the Potoo gets obscured behind a branch, the Potoo is sitting slightly more distant than the kite and would thus appear just a bit smaller and there are differences in posture. Even though it is impossible to correct for these errors, the comparative size of the Potoo is very obvious. With the assumption that the kite is approximately 35 cm, The Potoo is just a little more than 50 cm. The Northern Potoo is about 40 cm, so based on size, a Northern Potoo (and the most owl species for that matter) could be ruled out.

Great Potoo confirmation

To get the call confirmed, Mark McReynolds arranged for the original of the recording to be sent to the Cornell Lab of Ornithology Ithaca, New York , USA.

On October 22, 2009, Tammy Bishop (Cornell) wrote: “Our audio curator thinks that it’s a Great Potoo, but has forwarded your message on to someone here at the Lab who has more experience with South American birds”.

Following that message, on November 18, Greg Budney (Cornell) wrote: “This morning I played your recording to Mario Cohn-Haft who's name you may be familiar with from his research on Potoos. Mario stated that your recording is unequivocally Great Potoo”.

With the identification thus sufficiently demonstrated, the Great Potoo, can now be accepted as a component of the Belize avifauna. Whether this is as permanent resident or just as a visitor remains to be seen.

The recording has been deposited as an acoustic voucher specimen (#ML 140397) in the Macaulay Library at Cornell Lab of Ornithology.

The observation record has been entered in the Biodiversity & Environmental Resource Data System of Belize (BERDS): http://www.biodiversity.bz/find/specimens/profile.phtml?dcid=112860 A low resolution copy of the video/audio file is available at: http://www.biodiversity.bz/find/resource/profile.phtml?dcid=112859

Metadata:

  • Recorder: Jan Meerman
  • Location: Green Hills Butterfly Ranch, Cayo District, Belize. UTM E:289900 N:1891220 (UTM NAD 1927, Zone 16N) or 17°05’52.17”N, 88°58’26.60”W.
  • Date: September 30, 2009
  • Time of day: 00.05 hrs (just after midnight)
  • Weather: Clear night with nearly full moon. Very bright, clouds and lightning in the distance.
  • Habitat description: Mosaic of Mature forest, secondary forest, pasture and farmland. Bird sitting on a dead snag of a free standing Cedar Tree (Cedrela odorata)
  • Manufacture and Model of recording device: Canon Powershot SX10IS still camera with video capability.
  • Manufacture & model of microphone: As above.
  • Original format: Gre_Pot_4387.jpg still image + MVI_4382.MOV QuickTime Movie
  • Comments: Recording with loud chorus of frogs in the background.

 

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