Etienne Marais’s scientific contributions

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Publications (1)

Figure 2. One of hundreds of Forbes-Watson's Swifts A. berliozi in a low-flying flock, Kijongo Bay, Tanzania, March 2017 (J. Haureljuk)
Figure 3. Comparison of mean (circle) frequency (kHz) at peak amplitude (Pk) of the screaming calls of 'Inhassoro swifts' with Forbes-Watson's Apus berliozi, Nyanza A. niansae, African Black A. b. barbatus, Malagasy Black A. balstoni, Pallid A. pallidus, Common (A. a. apus and A. a. pekinensis) and Bradfield's Swifts A. bradfieldi. Bars show 95% range in values (± 1.96 SD), and range for 'Inhassoro swifts' shown as broken lines.
Figure 6. Comparison of throat patches of Forbes-Watson's Swift A. berliozi (left) and Common Swift A. a. pekinensis (right). Dimensions from Grieve & Kirwan (2012); in A. b. bensoni depth (from base of bill): mean 25.5 mm (range 21.6-29.8 mm), width (at widest point): 22 mm (range 15.7-25.2 mm); in pekinensis depth: 22 mm (range 15.6-26.5 mm), width: 16 mm (range 12.1-20.7 mm). Minimum dimension indicates the lower ranges, maximum, upper ranges, and the illustrated throat patch the mean dimensions. Note slightly whiter ground tone and fine throat streaks in Forbes-Watson's Swift (Faansie Peacock)
First record of Forbes-Watson's Swift Apus berliozi in southern Africa, with comments on vocal and visual identification
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March 2021

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4 Citations

Bulletin of the British Ornithologists Club

Etienne Marais

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Faansie Peacock

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We report the first record of Forbes-Watson’s Swift Apus berliozi for the southern Africa region from coastal southern Mozambique. Identification was primarily based on vocal characters using sonogram analyses, which show that voice is diagnostic compared to all seven possible confusion species in the region. Current knowledge of the distribution and life history of A. berliozi is summarised, which shows that the Mozambique record extends the non-breeding range c.1,700 km south and suggests that Forbes-Watson’s Swift is a migrant to the littoral of Tanzania and northern and central Mozambique. Field identification of Forbes-Watson’s Swift using visual characters is challenging, but information is presented to aid separation from the most likely confusion species, Common Swift A. apus.

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Citations (1)

... This suggests that the thinner MTM documented in echolocating swiftlets is probably not an adaptation to echolocation and may instead be ancestral to Apodidae, which would be congruent with the lack of phylogenetic signal in swiftlet echolocating calls (Thomassen and Povel 2006 two independent acquisitions of the trait. Such a structure could provide a structural advantage for sustained high-frequency vocalization, since A. apus and other species in the same genus have been documented to produce relatively long calls (~400 ms) at 5.6 kHz (Malacarne et al. 1989, Grieve and Kirwan 2012, Marais et al. 2021, i.e. within the frequency range of echo clicks produced by echolocating swiftlets (Thomassen and Povel 2006). Accordingly, in hummingbirds, local thickening of the MTM to form a medial labium with tympanic ossicles has been proposed to facilitate high-frequency vocalizing through increased stiffness (Monte et al. 2020). ...

Reference:

Evolution of the syrinx of Apodiformes, including the vocal-learning Trochilidae (Aves: Strisores)
First record of Forbes-Watson's Swift Apus berliozi in southern Africa, with comments on vocal and visual identification

Bulletin of the British Ornithologists Club

Etienne Marais

·

Faansie Peacock

·