Voice comparison of the Southern and Northern Band-tailed Pigeons

The Northern Band-tailed Pigeon (Patagioenas fasciata) and Southern Band-tailed Pigeon (P. albilinea) have recently been given separate species rank, primarily on the basis of morphological differences (del Hoyo & Collar 2014). The following brief analysis, using available on-line recordings from Xeno Canto (XC) and the Macaulay Library (ML), compares their songs. The basic song parameters of both species were compared (Table 1), including examples of the subspecies fasciata and monilis of the Northern Band-tailed Pigeon (n = 10; there were no available recordings of vioscae) and of the three currently recognized subspecies of the Southern Band-tailed Pigeon: albilinea, crissalis and roraimae (n = 12, including only one recording of roraimae).

Table 1. Basic song parameters of the Southern and Northern Band-tailed Pigeons.

The song of the Southern Band-tailed Pigeon (Fig. 1) is a series of repeated single hoots: hooo... hooo... hooo..., with the first note of a series typically being softer and slightly lower-pitched. In the Northern Band-tailed Pigeon the song is a series of rather soft low-pitched coos, typically starting with a single note and followed by repeated bi-syllabic notes: rwhoo... hu-hooo... hu-hooo... hu-hooo… These bi-syllabic notes are sometimes separated, resulting in two notes. The first syllable is shorter (0·11–0·19 s vs. 0·46–0·62 s) and higher pitched than the second.

Southern Band-tailed Pigeon sonogram 

Northern Band-tailed Pigeon sonogram 

Figure 1. Representative sonograms of Southern (above) and Northern (below) Band-tailed Pigeons.

Two recordings that do not fit the above descriptions require comment. A recording of the Southern Band-tailed Pigeon from the Santa Marta Mountains in Colombia (XC236033) seems to have a barely audible hiccup before every hoot, but the amplitude ratio with long hoot appears to be dramatically different from the Northern Band-tailed Pigeon. Recording ML70842 of a presumed Northern Band-tailed Pigeon comprises a series of single hoots but was recorded in Belize, beyond the species geographical range and below its typical altitudinal range. The comment accompanying this recording says: “Unidentified by Parker, this was positively ID's by Pablo Tubaro, with 100% confidence”, suggesting that there was no visual confirmation. It seems far more likely that this recording is of the Grey-headed Dove (Leptotila plumbeiceps), which has a slightly longer hoot but otherwise sounds quite similar to the Southern Band-tailed Pigeon.

The above data show quite clear vocal differences between the Southern and the Northern Band-tailed Pigeons. Despite the small sample size, some of them can tentatively be scored using the criteria proposed by Tobias et al. (2010). The first syllable of the Northern Band-tailed Pigeon song reaches higher frequencies (score 2–3), and as a result the total frequency range is greater (score 2–3). Its bi-syllabic vs. mono-syllabic note is reflected in the location of the maximum frequency (score 3) and the overall note length (score 1–2), or could alternatively be expressed as one syllable vs. two syllables (or notes) (score 3–4). The song pace of the Northern species also averages slightly slower, due to the combination of the longer note length with similar pauses (score 1). Taking the largest two independent scores, the total score for vocal differences is 5–6.

This brief analysis confirms that these two pigeons have different songs, which further supports their treatment as two distinct species.

References

Del Hoyo, J. & Collar, N.J. (2014). HBW and Birdlife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions, Barcelona.

Tobias, J.A., Seddon, N., Spottiswoode, C.N., Pilgrim, J.D., Fishpool, L.D.C. & Collar, N.J. (2010). Quantitative criteria for species delimitation. Ibis 152(4): 724–746.