SPECIES

Short-clawed Lark Certhilauda chuana Scientific name definitions

G. Derek Engelbrecht
Version: 2.0 — Published February 23, 2023

Sounds and Vocal Behavior

Introduction

Short-clawed Lark uses a range of vocalizations to communicate. Adult vocalizations include song, contact, agitated, alarm, and nestling feeding calls, while nestlings use begging and distress calls. The song is rather stereotypical, with each male possessing a limited range of 3–6 phrases, seemingly delivered in random order. Given the species' sedentary nature, it is not surprising that distinct dialects exist within and between the western and eastern populations, but whether these dialects have a taxonomic basis is unknown. Short-clawed Lark does not include heterospecific vocal mimicry in its vocal repertoire.

Vocalizations

The vocal repertoire of Short-clawed Lark is similar to its congeners, but is distinctive within its distribution. Vocalizations belong to three categories comprising seven types: song (by males only and including a territorial and display flight song), a range of contact-type calls including agitated, alarm, and nestling feeding calls, and two types of nestling calls, a begging and a distress call (46). Heterospecific vocal mimicry has not been recorded for Short-clawed Lark (46).

Development

Two types of nestling calls can be distinguished: begging and distress calls (46). Begging calls are high-pitched peep calls delivered when parents deliver food. Distress calls are only produced towards the end of the nestling period and when the nestlings are disturbed, e.g., during handling or when seized by a predator. Distress calls are short, harsh, and grating vocalizations of a relatively constant frequency.

Vocal Array

Songs

The song is rather stereotypic and performed by males only. It comprises a single whistle or series of whistles in a broad frequency range (2,033–8,666 Hz) (46). A brief, sometimes barely audible, introductory note usually initiates a phrase (1). Two song types can be distinguished: territorial song and display song.

Territorial song. Characterized by phrases comprised of 1–4 (rarely up to 7) clear elements that are either ascending, descending, or of a constant frequency (46). The frequency of the individual elements in a phrase also varies (1). Despite the many possible combinations of elements, each male in the Polokwane region possesses a limited number of 3–6 signature phrases that are unique to that individual (46). These phrases seem to be delivered in a random pattern, occasionally with slight variations in frequency or the presence or absence of an element (46). There is geographical variation in male songs (see Geographic Variation, below).

Flight display song. Structurally similar to the territorial song. It always comprises a single element and is delivered towards the end of a display flight. It is characterized by a relatively constant frequency and lasts 1.04 s ± 0.07 SD (range 0.96–1.13, n = 13) (46). Two display song types can be distinguished, a high-frequency flight display song averaging 7,334.64 Hz ± 152.23 SD (n = 9) and a low-frequency flight display song averaging around 3,529.13 Hz ± 49.14 SD (n = 4) (46).

Calls

Contact call. Both sexes deliver contact calls, relatively low-frequency calls ranging from 1–4 elements (46). A single-note contact call often heard while foraging, described as a drawn-out peeeu, maintains contact between individuals. When there is a potential threat, contact calls become more urgent and grade into alarm calls, typically comprising 2–4 elements delivered in quick succession, e.g., pip-peeu-peeu, peeu-weeu. Although mainly stereotypic, contact calls occasionally show some individual variation, e.g., the inclusion of a trill or frequency modulation of the elements (e.g., M. Herremans, XC667448; 13). Contact calls are the lowest frequency vocalizations (range 1,728–3,978 Hz) in the vocal repertoire (46).

Agitated call. The Agitated call is characterized by a jumble of syllables made up of harsh trills and clear whistles of varying duration, frequency, and intensity, e.g., ree-teee-ree–tee-kreee-oooo. These syllables are arranged in phrases comprising 2–10 syllables (mean of 5.44 syllables ± 1.58 SD, n = 126) and cover a broad frequency range of 1,908.8–7,501.2 Hz (n = 20). Although delivered by both sexes, female agitated calls are slightly more muted than those of the male.

Chattering call. The Chattering call has only been recorded twice, and, in both instances, it was delivered by a male at the end of a brooding bout. It may be an alternative expression of a contact call (46).

Geographic Variation

Geographic variation in the territorial song and alarm calls has been reported within and between the eastern and western populations (31, 48, 1, 35). Short-clawed Lark appears to have two distinct dialects across its range. Both the western and eastern populations possess a complex, musical dialect and a simpler, stereotypical dialect with fewer syllables. On a local scale within each population, specific dialects are evident across insignificant geographic or ecological features such as low ridges, bush-encroached areas, unsuitable soils such as deep Kalahari sands, and non-perennial rivers (31, 48, 1). These specific dialects are also maintained on a regional scale, despite seemingly greater geographic and ecological barriers for the species, e.g., the low-lying Limpopo River valley and stretches of broad-leaved savannah woodland. The result is that in some instances, the territorial song of populations that are 400 km apart are more similar than populations separated by less than 10 km in seemingly identical habitats (1). The musical dialect is seemingly confined to northeastern Botswana (referred to as the “north-central” dialect by 48), and the western Polokwane Plateau (referred to as the “western” dialect by 1). Although there is no territorial song recording from the population discovered at Bojanala in 2019, the alarm calls correspond with alarm calls of north-central birds in Botswana. The simple, stereotypical dialect is found in northern (35) and southwestern Botswana (referred to as the “south-central” dialect by 48), the Northern Cape and North West provinces of South Africa (the same as the “eastern dialect (west)” referred to by 1), and the eastern Polokwane Plateau in the Limpopo Province, South Africa (referred to as the “Polokwane Plateau eastern” dialect by 1). The distribution and persistence of these dialects may have systematic implications, i.e., the dialects may represent cryptic species (1).

In Botswana, the simple dialect, restricted to extreme south-western Botswana, typically consists of fewer elements per phrase, usually only one or two, and the elements tend to be longer and have a smaller frequency range. The musical dialect in northeastern Botswana tends to have more elements, usually 3–4 but up to eight in a phrase, the elements are shorter, and the frequency range is greater (48). The simple dialect of the eastern population on the Polokwane Plateau typically comprises 2–3 elements per phrase (mean of 2.3 elements/phrase ± 0.97 SD, range 1–6; n = 333), and tends to be above 5 kHz. An isolated northern population shows a minor deviation from this pattern with a slanted expression of the introductory note (1). The complex dialect on the Polokwane Plateau typically possesses 3–4 elements per phrase (mean of 2.64 elements/phrase ± 1.47 SD, range 1–7; n = 169), tends to be lower than 5 kHz, the introductory element (when present) is J-shaped, and the following elements typically appear like an inverted S (1, 46).

Phenology

Short-clawed Lark vocalizes throughout the year, but seasonal and daily variations exist in the delivery of the different vocalizations. Territorial singing peaks during the peak breeding season, i.e., summer November–January (mean of 873.5 calls/day ± 190.1 SD, range 637–1,094), and is lowest during the non-breeding season, i.e., winter (mean of 52.8 calls/day ± 38.4 SD, range 5–96) (46).

Contact calls are delivered throughout the year. Contact calls, specifically alarm calls, reach their greatest delivery rate in the peak breeding season as Short-clawed Lark is extremely wary when it has an active nest (46).

Agitated contact calls peak in autumn when many young birds disperse from their natal territories. The pair bond begins to dissolve, with females usually dispersing from the nesting territory (46).

Daily Pattern of Vocalizing

Territorial singing peaks in the morning, within two hours after sunrise, but there is a second, smaller peak in the late afternoon in summer and autumn (46). Contact calls peak within the first two hours after sunrise. As with other calls, agitated calls tend to peak in the mornings, but the peak is not as distinct as with other vocalizations (46).

Places of Vocalizing

The territorial song is usually delivered from an elevated position such as a bush, fence, rock, or termite mound, but occasionally from the ground.

Sex Differences

Territorial song and Flight display song are only uttered by the male. Both sexes deliver contact calls. Agitated call is also delivered by both sexes, but female agitated calls are slightly more muted than those of the male. Chattering call has only been observed for a male bird.

Repertoire and Delivery of Songs

Each male in the Polokwane region possesses a limited number of 3–6 signature phrases that are unique to that individual.

Social Context and Presumed Functions of Vocalizations

Both song types have likely a territorial function. Contact calls are often heard while foraging, to keep contact between individuals. An alternative multi-note version can be heard in situations of potential threat, and is thus likely an alarm call. Agitated calls are delivered in different contexts: they are often associated with aggressive intraspecific encounters between males or neighboring pairs, or by a male performing sentinel duties near an active nest. An attenuated version of the agitated call is given by both sexes when delivering food to nestlings and appears to stimulate nestlings to gape for food (46).

Nonvocal Sounds

No nonvocal sounds were reported by Engelbrecht and Grosel (46), but Dean and Keith (14) describe “wing clapping” during a fluttering courtship flight, however it is not clear if this was audible and would therefore constitute a nonvocal sound.

Recommended Citation

Engelbrecht, G. D. (2023). Short-clawed Lark (Certhilauda chuana), version 2.0. In Birds of the World (D. G. Allan, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.shclar1.02