Bioacoustics of Catharus fuscater

Diagnosis Genetics: In the ND2 reconstruction, samples from the range of C. f. fuscater formed a clade that was sister to a single sequence of C. f. sanctaemartae (mean uncorrected p -distance = 0.02 ± <0.01), with an estimated divergence of 0.7 Mya (95% HPD = 0.31– 1.21). This corroborates Cuervo (2013) , who found that C. f. fuscater and C. f. sanctaemartae were sisters, with broader sampling of ND2 sequences from within the range of C. f. fuscater . ABGD analysis of ND2 data identified C. f. sanctaemartae as an independent genetic cluster, but ASAP analysis merged it with C. f. fuscater . We lacked UCE data for C. f. fuscater and C. f. sanctaemartae , so further research will be needed to confirm their sister relationship, to determine their placement in the broader phylogeny of the complex, and to evaluate whether C. f. sanctaemartae is deserving of species rank. Morphology: Unlike C. f. sanctaemartae , the phenotype of C. f. fuscater shows puzzling patterns of dichromatism. An unsexed specimen (ANSP 16106) from ‘Santa Fe [de Bogotá ]’ in ‘New Grenada’ closely resembles ‘brown type’ males and female specimens of C. [ f. ] mentalis (e.g. FMNH 433738, 433740) and an individual from Cesar , Colombia , has a brownish dorsal surface (ML 4670402810). In contrast, C. f. fuscater adults in the CM collection, collected in Santander and Norte de Santander , Colombia , show no brown on the dorsal surface, although in only one case were multiple individuals collected at the same site. Specimens of C. f. sanctaemartae have darker ventral plumage than any other taxon, including C. f. fuscater ( Fig. 13 ), rivalled only by C. hellmayri , from which it is distinguished by having more black on the chin (Todd and Carriker 1922) and a longer tail ( Hellmayr 1934 ). We lacked fresh specimens of C. f. sanctaemartae , so were unable to thoroughly evaluate the claim that males are ‘darker and more richly coloured’ than females (i.e. a reported difference in brightness, not hue; Allen 1900 , Todd and Carriker 1922). However, no clear differences in plumage colour or brightness are evident in male and female specimens collected by Carriker on 16 May 1925 , at La Cumbre, Magdalena , Colombia (FMNH 72426, 72427). Voice: The combination of Type 2 punctuation calls ( Fig. 9 ) and ‘widely spaced’ contact calls ( Fig. 10 ) in recordings of C. f. fuscater and C. f. sanctamartae distinguish them from C. hellmayri , C. arcanus sp. nov. , and C. mirabilis . Punctuation calls were more elaborate and variable in C. f. fuscater than any other South American taxon ( Fig. 9 ). An exceptional set of C. f. fuscater recordings (ML 66348 –66356) by P. Schwartz features individual birds responding to playback by cycling through repertoires of multiple, distinct Type 2 (‘long/ sinuous’) punctuation calls, and one recording features a Type 3 (‘short/simple’) punctuation call, reminiscent of the calls of C. [ f. ] opertaneus , Undescribed 2, Undescribed 3, and C. [ f. ] mentalis , but with a greater frequency range (see Fig. 9 ). The descending blurred call detected in C. f. fuscater recordings was similar in frequency to, but wider in bandwidth than, the blurred calls of C. [ f. ] berlepschi ( Fig. 11 ); no recordings of blurred calls were available for C. f. sanctaemartae . In song, the ascending dyadic contour (AB) was more prevalent in C. f. fuscater and C. f. sanctaemartae than in any other taxa ( Fig. 12 ). Of the four triadic contours detected in C. f. fuscater (ABC, ACB, BAC, CAB), two were shared with C. f. sanctaemartae (ABC, BAC). Of the three triadic contours detected in C. f. sanctaemartae (ABC, BAC, BCA), two were detected in C. f. fuscater (ABC, BAC). The only tetradic contour detected in C. f. fuscater (DABC) was not detected in C. f. sanctaemartae , which had three tetradic contours of its own (ABCD, BCAD, CDAB). The rare contour BCAD, detected in only one recording of C. f. sanctaemartae (ML 215345031), was not detected in any other taxon.