In the following we briefly analyze and compare voice of the different races of White-throated Spadebill (Platyrinchus mystaceus). We also try to quantify the extent of any vocal differences using the criteria proposed by Tobias et al. (2010), as a support for taxonomic review. We have made use of sound recordings available on-line from Xeno Canto (XC) and Macaulay Library (ML).
White-throated Spadebill is typically detected in the field by its day-time voice, abrupt single or multiple calls. Much less known is its song, which is mostly given at dawn and early morning. As a consequence, despite being a fairly common bird in most of its range, there are relatively few recordings of its song. The song is a trilled sequence of notes, and features are somewhat variable depending on the excitement of the bird (e.g. after playback). As such, there is more variation in this analysis of the recordings than would probably be the case if only song under natural conditions would be analyzed. Nevertheless, the analysis showed some very interesting results.
We studied 5 groups:
1. the W Andean group (neglectus, albogularis)(no recordings of perijanus): The song is a series of rising notes, introductory note is typically lowest in pitch and longer than subsequent notes.
2. The E Andean group (zamorae): The song is a series of rising notes, introductory note is typically lowest in pitch and longer than subsequent notes. Very similar to the previous group.
3. The S Andean group (partridgei): The song is a series of notes, first falling then rising, introductory and end note are thus more or less on same pitch.
4. The Caribbean group (insularis)(no recordings of imatacae, ptaritepui, duidae, ventralis): The song is a series of falling notes, well separated introductory note highest in pitch and longer than subsequent notes, which are given at a much faster pace than previous group.
5. The Brazilian group (mystaceus, cancromus)(no recordings of bifasciatus, niveigularis): The song is a series of falling notes, introductory note highest in pitch and longer than subsequent notes, which are given at a much faster pace than group 1-3. Overall very similar to group 4.
We have measured basic sound parameters for all available recordings of song (n=29).
Because of the vocal similarities, we have clustered group 1 and 2 and group 4 and 5 in our calculations.
Cluster 1: the northern Andean group (neglectus, albogularis,zamorae)(no recordings of perijanus)
Cluster2: the southern Andean group (partridgei)
Cluster 3: The Caribbean/Brazilian group (insularis, mystaceus, cancromus)(no recordings of of imatacae, ptaritepui, duidae, ventrali, bifasciatus, niveigularis)
Cluster 1 and 3 have the largest divergence: Introductory note frequency (effect size 6.29, score 3) , pitch trend (effect size 5.08, score 3), number of notes (effect size 2.68, score 2) and pace (effect size 4.034, score 2). Cluster 2 is actually intermediate (first falling then rising, a little bit of both!), but closer to Cluster 1. Difference with Cluster 1 is mainly introductory note frequency (effect size 4.73, score 2) , frequency evolution (effect size 2.77, score 2). Interestingly, this seems to be exactly the same conclusion as in HBW (Tello 2015) based on morphological characters (e.g. cluster 1 dark lower mandible, cluster 3 pale lower mandible, cluster 2 intermediate), including the rather surprising affinity between Brazilian and N Venezuelan races.
We can thus conclude:
(Northern/Andean) White-throated Spadebill: The song is a rising series of notes, with the lowest pitched introductory note longer. Compared with 'Eastern White-throated Spadebill' which has a falling series with high-pitched introductory note and much faster pace, main differences are frequency of introductory note (effect size 6.29, score 3), frequency evolution (effect size 5.08, score 3), number of notes(effect size 2.68) and pace (effect size 4.034). When applying Tobias criteria this would lead to a total vocal score of 6.
(Eastern) White-throated Spadebill: The song is a fast descending series of notes, with a long high-pitched introductory note. Compared with 'Northern/Andean White-throated Spadebill' which has a rising slower song, main differences are pitch of introductory note (effect size 6.29, score 3), pitch trend (effect size 5.08, score 3), number of notes (effect size 2.68) and pace (effect size 4.034). Total score 6.
(Southern Andean) White-throated Spadebill: The song is a falling then rising series of notes, with introductory and end note well pronounced and at similar pitch. Compared with (Northern) Andean White-throated Spadebill which has a rising song, , main differences are frequency of introductory note frequency (effect size 4.73, score 2) and frequency evolution (effect size 2.77, score 2). Total score 4.
If partridgei would not reach the treshold for species recognition based on all characters together, then it is closest to the Northern Andean group, and should be included in this enlarged Andean group, while giving it a separate group status.
The main differences of the enlarged Andean group compared to the Eastern group are: Eastern group has a song starting with higher-pitched introductory note (2) and is followed by many more notes (2) given at much faster pace (2), with an overall longer duration (1).
We did not analyze the possible difference in call notes.
This note was finalized on 20th March 2015, using sound recordings available on-line at that moment. We would like to thank in particular the sound recordists who placed their recordings of song for this species on XC and ML: Roger Ahlman, Ciro Albano, Nick Athanas, William Belton, Peter Boesman, Miguel Castelino, Eric DeFonso, Jerome Fischer, Ricardo Gagliardi, Niels Krabbe, Frank Lambert, Mitch Lysinger, Sjoerd Mayer, Jeremy Minns, David Ross, Thomas Schulenberg and Andrew Spencer.
Tello, J. (2015). White-throated Spadebill (Platyrinchus mystaceus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/57317 on 20 March 2015).
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.
More Information: on115_white-throated_spadebill.pdf