Hartlaub's Francolin
Encyclopedia
The Hartlaub's Spurfowl, or Hartlaub's Francolin, Pternistis hartlaubi is an endemic
bird
species of the escarpment zone of Namibia
and Angola
. Its name commemorates the German zoologist Gustav Hartlaub
.
species). The bare parts are mostly a dull yellow; the large bill is a brownish yellow.
Male: Strong contrast of mottled buff/brown upperparts and white underparts streaked with brown. Black forehead with white eyebrow conspicuous. Black-and-white barred undertail coverts especially diagnostic in flight. Female: Like male, but with cinnamon (not white) unstreaked underparts, grey-brown head and orange-brown eyebrow. Lacks undertail barring of male. Juvenile: Buffy forehead and brown crown tinged with rufous. Upperparts buffy grey with black and white vermiculations. Breast barred black and white, with buffy grey belly
:
, occurring only in northcentral to northwestern Namibia
and a small area of southwestern Angola
. It is not especially common throughout its limited range. The Namibian population is estimated at c. 26 000 birds. However, this bird's conservation status is not threatened, probably because its habitat is of little commercial
value to humans at this stage. Granite mining activities are a potential threat to their habitat. Though Francolins are a gamebird, Hartlaub's is too small to be of any special culinary value.
and semi-arid
regions from 800-1600m (2600–5200 ft). Throughout its range its preferred habitat consists of higher ground, mostly on rocky granite and sandstone outcrops (popularly known as "koppies" to locals), surrounded by semi-desert steppe. There is invariably relatively dense grass and shrubbery associated with these outcrops.
s, seed and insects of different sizes in different habitats. Hartlaub's Francolin primarily forage on granitic outcrops, and use a variety of feeding techniques, with significant sexual differences in foraging behaviour and, to a lesser degree, dietary composition.
Males consume a greater diversity of food items than females, although there is considerable dietary overlap between the sexes, and sexual differences in feeding techniques result in some food items being prioritized by each sex. In particular, distinct functional differences results from females' almost exclusive digging habits, in contrast to males' wider range of foraging techniques, including an apparently male-specific foraging technique of exposing cryptic termites.
The relatively larger-billed females specializes on digging out the corms of Cyperus sp
which, within the species, appears to be primarily carried out by females, with males spending proportionally more time foraging for a more diverse diet of insects and seed. It is hypothesized that this sexual difference in diet is adaptive, in response to predator and sexual selection pressures. The relatively narrow dietary spectrum of female Hartlaub's Francolins may be a causative factor in vigorous perennial defence of territorial resources.
Hartlaub's Francolins occur in pairs or small family parties of 3-4 and are inconspicuous unless calling . They are not easily flushed, preferring to hide between boulders. Flushed birds will utter a rapid, chattering 'krak', flying rapidly.
Red-billed Francolin
and Orange River Francolin
occur alongside this species, but they occupy different habitats. The Red-billed Francolin
prefers bush along watercourses and Orange River Francolin
can be found on the slopes leading up to the rocky outcrops occupied by the Hartlaub's Francolin .
Antiphonal duets of territorial pairs are audibly distinguishable, on the basis of temporal and structural differences in the female vocal elements of duets. Territorial pairs use antiphonal duets on a daily basis to advertise their presence, and such calling was most frequent shortly after sunrise. Un-mated females call far more frequently than territorial pairs, often throughout the day, with peaks at shortly after sunrise and before sunset. Playback experiments with the advertising calls of un-mated females within territory boundaries of established pairs, elicited vigorous vocal and behavioural responses from territorial females. Male calls are more conservative than female calls, with females using a wider repertoire of vocalizations.
The mating system of Hartlaub's Spurfowl can be described as a female dominated resource defence monogamy. Perennial territorial resources (food, traditional call-sites, refuge and suitable nest-sites) are primarily defended by female Hartlaub's Francolins. By excluding other females from the vicinity of the resource, the defending female can count on male visitation, life-mating and thus biased mating access with guaranteed fertilization. The pair bond is maintained by ritualised behaviours, including pair-distinct (female initiated) antiphonal duetting and reverse mounting during courtship and incubation. Operational sex ratios are "female skewed" and probably strongly influenced by predation, with noticeably large numbers of strongly- vocal female 'floaters' and a virtual absence of un-mated males. It is unusual that this sex-role reversed monogamy occurs in a species which is strongly sexually dichromatic and dimorphic, with the males more brightly coloured and somewhat larger than females.
Endemism in birds
An endemic bird area is a region of the world that contains two or more restricted-range species, while a "secondary area" contains one or more restricted-range species. Both terms were devised by Birdlife International....
bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
species of the escarpment zone of Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
and Angola
Angola
Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...
. Its name commemorates the German zoologist Gustav Hartlaub
Gustav Hartlaub
Karel Johan Gustav Hartlaub was a German physician and ornithologist.Hartlaub was born in Bremen, and studied at Bonn and Berlin before graduating in medicine at Göttingen. In 1840, he began to study and collect exotic birds, which he donated to the Bremen Natural History Museum. He described some...
.
Appearance
A small, squat bird; both sexes of this species have disproportionately large bills for their size (in comparison to other FrancolinFrancolin
Francolins are birds that traditionally have been placed in the genus Francolinus, but now commonly are divided into multiple genera , although some of the major taxonomic listing sources have yet to divide them. They are members of the pheasant family, Phasianidae...
species). The bare parts are mostly a dull yellow; the large bill is a brownish yellow.
Male: Strong contrast of mottled buff/brown upperparts and white underparts streaked with brown. Black forehead with white eyebrow conspicuous. Black-and-white barred undertail coverts especially diagnostic in flight. Female: Like male, but with cinnamon (not white) unstreaked underparts, grey-brown head and orange-brown eyebrow. Lacks undertail barring of male. Juvenile: Buffy forehead and brown crown tinged with rufous. Upperparts buffy grey with black and white vermiculations. Breast barred black and white, with buffy grey belly
Measurements
- Length: Male 28 cm (11 in) Female 25 cm (10 in).
- Weight: 210-290g (~0.5-0.63 lb); the male is heavier than the female.
Subspecies
There are three recognized subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
:
- P. h. bradfieldi (RobertsAustin RobertsAustin Roberts was a South African zoologist. He is best known for his Birds of South Africa, first published in 1940. He also studied the mammalian fauna of the region: his work The mammals of South Africa was published posthumously in 1951...
, 1928) - P. h. crypticus (StresemannErwin StresemannErwin Stresemann was a German naturalist and ornithologist.Stresemann was one of the outstanding ornithologists of the 20th century...
, 1939) - P. h. hartlaubi (Bocage, 1869)
Distribution and status
Hartlaub's Spurfowl is endemic to southwest AfricaAfrica
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, occurring only in northcentral to northwestern Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
and a small area of southwestern Angola
Angola
Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...
. It is not especially common throughout its limited range. The Namibian population is estimated at c. 26 000 birds. However, this bird's conservation status is not threatened, probably because its habitat is of little commercial
Commerce
While business refers to the value-creating activities of an organization for profit, commerce means the whole system of an economy that constitutes an environment for business. The system includes legal, economic, political, social, cultural, and technological systems that are in operation in any...
value to humans at this stage. Granite mining activities are a potential threat to their habitat. Though Francolins are a gamebird, Hartlaub's is too small to be of any special culinary value.
Habitat
Hartlaub's Spurfowl is an inhabitant of medium-altitude aridArid
A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...
and semi-arid
Semi-arid
A semi-arid climate or steppe climate describes climatic regions that receive precipitation below potential evapotranspiration, but not extremely...
regions from 800-1600m (2600–5200 ft). Throughout its range its preferred habitat consists of higher ground, mostly on rocky granite and sandstone outcrops (popularly known as "koppies" to locals), surrounded by semi-desert steppe. There is invariably relatively dense grass and shrubbery associated with these outcrops.
Behaviour and diet
Habitat use, foraging behaviour and diet of male and female Hartlaub's Spurfowl are related to the availability of cormCorm
A corm is a short, vertical, swollen underground plant stem that serves as a storage organ used by some plants to survive winter or other adverse conditions such as summer drought and heat ....
s, seed and insects of different sizes in different habitats. Hartlaub's Francolin primarily forage on granitic outcrops, and use a variety of feeding techniques, with significant sexual differences in foraging behaviour and, to a lesser degree, dietary composition.
Males consume a greater diversity of food items than females, although there is considerable dietary overlap between the sexes, and sexual differences in feeding techniques result in some food items being prioritized by each sex. In particular, distinct functional differences results from females' almost exclusive digging habits, in contrast to males' wider range of foraging techniques, including an apparently male-specific foraging technique of exposing cryptic termites.
The relatively larger-billed females specializes on digging out the corms of Cyperus sp
Cyperus
Cyperus is a large genus of about 600 species of sedges, distributed throughout all continents in both tropical and temperate regions. They are annual or perennial plants, mostly aquatic and growing in still or slow-moving water up to 0.5 m deep. The species vary greatly in size, with small species...
which, within the species, appears to be primarily carried out by females, with males spending proportionally more time foraging for a more diverse diet of insects and seed. It is hypothesized that this sexual difference in diet is adaptive, in response to predator and sexual selection pressures. The relatively narrow dietary spectrum of female Hartlaub's Francolins may be a causative factor in vigorous perennial defence of territorial resources.
Hartlaub's Francolins occur in pairs or small family parties of 3-4 and are inconspicuous unless calling . They are not easily flushed, preferring to hide between boulders. Flushed birds will utter a rapid, chattering 'krak', flying rapidly.
Red-billed Francolin
Red-billed Francolin
The Red-billed Spurfowl , also known as the Red-billed Francolin, is a species of bird in the Phasianidae family. It is found in Angola, Botswana, Namibia, South Africa, Zambia, and Zimbabwe.-References:...
and Orange River Francolin
Orange River Francolin
The Orange River Francolin is a species of bird in the Phasianidae family found in grassland and woodland in Africa. In the taxa from the northern part of its distribution , the neck-line does not reach the eye and the belly is whitish...
occur alongside this species, but they occupy different habitats. The Red-billed Francolin
Red-billed Francolin
The Red-billed Spurfowl , also known as the Red-billed Francolin, is a species of bird in the Phasianidae family. It is found in Angola, Botswana, Namibia, South Africa, Zambia, and Zimbabwe.-References:...
prefers bush along watercourses and Orange River Francolin
Orange River Francolin
The Orange River Francolin is a species of bird in the Phasianidae family found in grassland and woodland in Africa. In the taxa from the northern part of its distribution , the neck-line does not reach the eye and the belly is whitish...
can be found on the slopes leading up to the rocky outcrops occupied by the Hartlaub's Francolin .
Breeding habits
Hartlaub's Spurfowls appear to be perennially territorial, with variable numbers of boundary call sites demarking each territory. Call-sites are used by territorial pairs on a regular basis, for daily bouts of antiphonal duets. The frequency of use of particular call-sites appears to be influenced more by the presence (vocalizations) of un-mated females on particular boundaries, than by the daily duetting of neighbouring pairs. The mean territory size of Hartlaub's Francolin pairs is 40863.9±12016.1 square metres (n = 12 pairs). Dependent on annual breeding success and offspring survival, the mean population density of the study area during 1983 through 1989 ranged from one bird in 0.82 ha to one bird in 2.04 ha, with an average annual population density of one bird in 1.43 ha. There was no significant difference in outer convex polygon areas determined by call sites and radio-telemetry. However, core ranges and utilization distributions of pairs, and, in particular, the multiple nuclei of different daily activities could only be distinguished by radio-telemetry. The 90% multiple nuclei of seasonal distribution are correlated with patchy distribution of food resources favoured by females, and, whilst rearing young, the distribution of insects, and especially cryptic termites.Antiphonal duets of territorial pairs are audibly distinguishable, on the basis of temporal and structural differences in the female vocal elements of duets. Territorial pairs use antiphonal duets on a daily basis to advertise their presence, and such calling was most frequent shortly after sunrise. Un-mated females call far more frequently than territorial pairs, often throughout the day, with peaks at shortly after sunrise and before sunset. Playback experiments with the advertising calls of un-mated females within territory boundaries of established pairs, elicited vigorous vocal and behavioural responses from territorial females. Male calls are more conservative than female calls, with females using a wider repertoire of vocalizations.
The mating system of Hartlaub's Spurfowl can be described as a female dominated resource defence monogamy. Perennial territorial resources (food, traditional call-sites, refuge and suitable nest-sites) are primarily defended by female Hartlaub's Francolins. By excluding other females from the vicinity of the resource, the defending female can count on male visitation, life-mating and thus biased mating access with guaranteed fertilization. The pair bond is maintained by ritualised behaviours, including pair-distinct (female initiated) antiphonal duetting and reverse mounting during courtship and incubation. Operational sex ratios are "female skewed" and probably strongly influenced by predation, with noticeably large numbers of strongly- vocal female 'floaters' and a virtual absence of un-mated males. It is unusual that this sex-role reversed monogamy occurs in a species which is strongly sexually dichromatic and dimorphic, with the males more brightly coloured and somewhat larger than females.