Rockjumper
| Rockjumpers | |
|---|---|
| |
| Cape rockjumper (Chaetops frenatus) | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Chaetopidae Fjeldsa, Ericson, Johannson, & Zuccon, 2015 |
| Genus: | Chaetops Swainson, 1832 |
| Species | |
The rockjumpers are medium-sized insectivorous or omnivorous birds in the genus Chaetops, which constitutes the entire family Chaetopidae. The two species, the Cape rockjumper, Chaetops frenatus, and the Drakensberg rockjumper, Chaetops aurantius, are endemic residents of southern Africa.[1] The Cape rockjumper is a resident of the West Cape and south-west East Cape, and the orange-breasted (or Drakensberg) rockjumper is distributed in the Lesotho Highlands and areas surrounding them in South Africa. The two rockjumpers have been treated as separate species but differ in size and plumage. The ranges do not overlap, but come close to doing so.
Taxonomy and systematics
Originally, these birds were placed in the thrushes, and they have also been placed with the Old World warblers and the babblers, but recent DNA studies indicate these birds are actually members of a basal group of oscines within the infraorder Passeri along with their sister-family the rockfowl (Picatharthidae), [2]
Some authorities (notably Dickinson and Christidis) treat the two rockjumpers as a single species, Chaetops frenatus, with two subspecies.[3]
Description
Both Rockjumper species are medium-sized passerines with mostly black, white, and red plumage. Both species have long, white tipped black tails, black throats, broad white submoustachial lines (malar stripes) and eyebrows, rufous or orange bellies and rumps, and grey and black patterned backs and wings. Females have similar pattern to males, but duller.[1] The iris is red and the bills and legs are black. Females are slightly smaller than males, and Drakensberg are slightly smaller than Cape (although taller, with longer tarsi). Immature birds resemble females, but lack the red iris, having one which is black.
Their wings are very small and they do not fly very often, although they will often take long gliding "flights" across valleys or downslope. They spend most of their lives running and jumping among rocks and grasses while hunting arthropods, small lizards, and amphibians.
Behaviour and ecology
Diet and feeding
The rockjumpers feed in groups, foraging on the ground. The groups can number up to 6 birds (for Cape) and 12 birds (for Drakensberg), but the groups may also spread out quite widely during feeding.[4][5] Insects are the major part of the diet, although small vertebrates are reported to be taken by Cape rockjumpers.[4] A range of insects are taken, including caterpillars, moths, grasshoppers, beetles and flies. In addition to insects other prey include lizards and geckos, amphibians, scorpions, annelid worms and spiders.
Breeding
They are monogamous and pairs establish territories which are defended year round. In the Cape Rockjumper the territories near Cape Town vary in size from 4–11 ha (10–27 acres), but are larger out east [6]. Both species employ helpers, usually the young of previous broods, to aid the breeding pair in raising the young.[7] Open nests are built on the ground under rocky overhangs, lined with red rock rabbit fur or seeds from nearby proteacea. While Cape Rockjumpers generally lay 2 eggs compared to the Drakensberg's 3, Cape have been recorded laying 3 eggs in years with good precipitation [8]. Both sexes incubate the clutch for 19–21 days. Chicks fledge at 19–21 days, although they are fed by the parents and helpers for up to 2 weeks following fledge. Eggs are plain white.
References
- ^ a b del Hoyo, J.; Elliot, A. & Christie D. (editors). (2007). Handbook of the Birds of the World. Volume 12: Picathartes to Tits and Chickadees. Lynx Edicions. ISBN 978-84-96553-42-2
- ^ Oliveros et al. 2019 "Earth history and the passerine superradiation" PNAS. 116: 7916-7925
- ^ Lepage, Denis. "Chaetops [frenatus or aurantius] (Rock Jumper) - Avibase". avibase.bsc-eoc.org. Retrieved 9 September 2017.
- ^ a b Collar, N., Robson, C. & Sharpe, C.J. (2017). Cape Rockjumper (Chaetops frenatus). 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/59691 on 4 July 2017).
- ^ Collar, N. & Robson, C. (2017). Drakensberg Rockjumper (Chaetops aurantius). 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/59692 on 4 July 2017).
- ^ Oswald, KN, B Smit, ATK Lee, and SJ Cunningham (2019). Behaviour of an alpine-endemic bird is described mainly by interactions between microsite and air temperature. An Behav. 157: 177-187
- ^ Holmes R, Frauenknecht B, & M Du Plessis (2002) "Breeding System of the Cape Rockjumper, a South African Fynbos Endemic" Condor 104 (1): 188–192 doi:10.1650/0010-5422(2002)104[0188:BSOTCR2.0.CO;2]
- ^ Oswald, KN, B Smit, ATK Lee, CL Peng, C Brock, SJ Cunningham. Under review. Reduced body condition for older nestlings is associated with higher temperatures in a range-restricted alpine bird. An. Beh.