WEAVERS - BIRD OF THE MONTH - JUNE & JULY 2014*

[nan]

Yellow Bishop (Yellowrumped Widow)/Euplecte à croupion jaune - Kysna


14.10.2012

[Lisbeth]

The Fan-tailed Widowbird (Euplectes axillaris), also known as Red-shouldered Widowbird is a species of bird in the Ploceidae family. It is found in Angola, Botswana, Burundi, Cameroon, Central African Republic, Chad, Republic of the Congo, Democratic Republic of the Congo, Ethiopia, Kenya, Lesotho, Malawi, Mali, Mozambique, Namibia, Niger, Nigeria, Rwanda, Somalia, South Africa, Sudan, Swaziland, Tanzania, Uganda, Zambia, and Zimbabwe.

Description
Length 15-17 cm. A short-tailed widowbird. Breeding male is the only small, short-tailed widowbird with a red shoulder.
Breeding male: Black with a pale blue-grey bill, red 'shoulders' and buff greater wing-coverts. The tail is fanned only in display.
Non-breeding male: Brown, dull with heavy blackish streaking above, a dark crown, conspicuous pale supercilium, red shoulder patches, and black primaries.
The female is similar but has brown primaries, and duller shoulder. Brown with blackish streaking above and reddish 'shoulders'.
Juvenile resembles female.
All ages and sexes have a distinguishing cinnamon underwing.

Distribution
Although it occupies small patches in West Africa, the bulk of its population occurs from Ethiopia through Tanzania, Zambia and Angola to southern Africa. Here it is fairly common in northern Botswana and the Caprivi Stip (Namibia), as well as from central Mozambique through to eastern and south-eastern South Africa.

Habitat
It generally prefers tall moist grassland and swamp edges, but at the coast also occurs in dry savanna and cultivation including sugarcane fields. It is gregarious, forming large post-breeding flocks. It roosts and feeds with other weavers.

Diet
It mainly eats grass seeds taken from the ground or directly from plants, occasionally foraging for insects. The following food items have been recorded in its diet: Grass seeds (Digitaria velutina Finger grass; Panicum maximum Guinea grass; Paspalum dilatatum Common paspalum; Echinochloa colona Jungle rice), insects (larval stage of Lepidoptera and termites).

Breeding
Polygynous solitary nester, as each male can mate with up to 4 females in a breeding season, defending a territory with up to 8 nests against other Euplectes species. It is thought the males with the largest and brightest shoulders (actually known as epaulets) are the most successful at setting up territories. The nest is built by the male and consists of an oval ball with a side entrance, made of woven grass strips and lined by the female with grass seed heads. It is typically placed in a clump of grass in marshy ground or in rank vegetation between sugar cane fields. Egg-laying season is from October-March, peaking from November-January. It lay 2-3 eggs, which are incubated solely by the female for about 12-13 days. The chicks are fed by the female only, leaving the nest after about 15-16 days, and remaining dependent on their mother for food for about two more weeks.

Call
Male utters a husky tseek, wirra, wirra, wirra, wirra when displaying.

[Lisbeth]

The Yellow-mantled Widowbird (Euplectes macroura), also known as the Yellow-backed Widow, is a species of bird in the Ploceidae family. It is the type species of the Euplectes genus, originally named from the city of Ouidah in Benin. Nowadays the name Whydah (i.e. Ouidah) is however applied to some species in the Viduidae.
Males are larger than females and acquire longer tails and striking black and golden yellow plumages in the breeding season. The mantle colour is either golden yellow, or in the case of the northeastern race, E. m. macrocercus, black. The yellow shoulders persist in all male plumages, whether breeding or non-breeding.

Its natural habitat is subtropical or tropical seasonally wet or flooded lowland grassland. It is widely distributed in Africa, and is found in Angola, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Malawi, Mali, Mozambique, Niger, Nigeria, Senegal, Sierra Leone, Sudan, Tanzania, Togo, Zambia and Zimbabwe.
The distinct race E. m. macrocercus occurs in Eritrea, Ethiopia, Kenya and Uganda.

[Lisbeth]

The White-winged Widowbird (Euplectes albonotatus) is a species of passerine bird in the family Ploceidae native to Africa south of the Sahara. It is highly sexually dimorphic in its breeding season, during which the male's yellow plumage turns dark and he gains more white feathers, contrasting with the female's predominantly pale coloration. Three subspecies are recognised.

Taxonomy
The White-winged Widowbird was first described by the American ornithologist John Cassin in 1848. Hybrids with "red bishops", probably Northern Red Bishop (E. franciscanus), have been reported in captivity. Non-captive interbreeding of race eques with nominate appears to occur in southern Tanzania, but they appear to stay segregated in Burundi and western Tanzania. A proposal has been made for race sassii, which is found along the northwestern shore of Lake Tanganyika. Alternate common names include: White-fronted/White-shouldered Widowbird, White-winged/White-shouldered Whydah, Long-tailed Black Whydah.

Description
The White-winged Widowbird is 15–19 cm in length and about 23 g in weight. The male is the only short-tailed widowbird in its region with white on its coverts. The breeding male is distinguished from the Yellow-mantled Widowbird by its shorter tail, wing color, lack of yellow on its back, and paler bill. Females are pale below.

Distribution and habitat
The White-winged Widowbird is found in Angola, Botswana, Burundi, Central African Republic, the Republic of the Congo, the Democratic Republic of the Congo, Ethiopia, Gabon, Kenya, Malawi, Mozambique, Namibia, Rwanda, São Tomé, South Africa, Sudan, Swaziland, Tanzania, Uganda, Zambia, and Zimbabwe. Its preferred habitats are savanna, grasslands and wetlands, as well as cultivated land. Its call is "zeh-zeh-zeh" and "witz-witz-witz".

Behaviour
The White-winged Widowbird is polygynous, with one male mating with 3–4 females, and lives in flocks. Oval nests, built solely by the male, are located in the branches of trees or shrubs. Nesting takes place from November to May, peaking from December to March. The female will lay a clutch of two to four white eggs, which she will incubate for 12–14 days. Feeding of chicks is done by the female in the nest for 11–14 days, with chick independence coming 22–25 days later. This bird mainly eats grass seeds, nectar, and insects.

[Lisbeth]

The Red-collared Widowbird (Euplectes ardens) is a species of bird in the Ploceidae family.Red-collared widowbirds are found in grasslands and bush clearings in Eastern and Southern Africa. They are known for their long tails and brilliant red badges, both which act as sexual ornaments. They are often associated with other Widowbird and Bishop species. They are polygynous, where males acquisition of territory is an important determinant in their access to mates. Red-collared widowbirds have a wide range and there is little concern in terms of conservation status.

Taxonomy
When Dutch naturalist Pieter Boddaert first described the Red-collared Widowbird from a South African specimen in 1783, he named it Fringilla ardens, assigning it to a genus of Old World finches. In 1829, William John Swainson created Euplectes, and moved the widowbirds and bishops from Fringilla into this new genus. Traditionally, Euplectes is thought to contain two clades, with the bishops in one clade and the widowbirds in another. However, molecular evidence suggests that the Red-collared Widowbird is actually a long-tailed bishop rather than a true widowbird.

Description
Similar to other widowbirds, male red-collared widowbirds have both seasonal and sexual dimorphism. Males are about 25 cm in length while females are only 13 cm. A similar trend is seen with weight, where males range from 20 to 26 g and females are only between 16 and 22 grams. During non-breeding seasons, the male plumage is brown, while in breeding season, October to April, they have black plumage with a long tail, approximately 22 cm, and crescent –shaped carotenoid based chest patch. There is significant variation in brightness, hue, and chroma of the carotenoid badges. In contrast, females and subadults, like nonbreeding males, are streaky dull brown with a short tail, approximately 4 cm. Nonbreeding males, however, retain their black tails, while females and subadults' tails are dark-brown.

Diet
Red-collared widowbirds feed on seeds of Sorghum and other grass seeds. They also feed on nectar, small berries, and insects, specifically ants, caterpillars, and termites. They often form large roosts, with between 50 and 100 individuals, which feed together on the ground. These roosts included breeding males. They are often formed with association with other species, like Red-billed Quelea, Fan-tailed Widowbird, Southern Red Bishop, White-winged Widowbird, and Yellow Bishop.

Distribution and habitat
Red-collared widowbirds are found throughout Eastern and Southern Africa. While their habitats are varied, they are often found in open grasslands,
agricultural areas, clearings in forests, and on slopes with limited tree coverage.
Euplectes ardens ardens are found in South Mali, North Guinea, inland Sierra Leone. North Liberia, North Ivory Coast, Southwest Niger, Central and Southeast Nigeria, Cameroon, Central African Republic, South Sudan, Democratic Republic of Congo, Central and Northeast Angola, Uganda, West Kenya, Tanzania, Malawi, Northwest and South Mozambique, Swaziland, and East South Africa.
Euplectes ardens laticauda are found in Southeast Sudan. Ethiopia, and Eritrea.
Euplectes ardens suahelicus are found in the highlands of Kenya and Tanzania.

Behavior and Ecology
Breeding and Mating Systems
Typical of polygynous species, male red-collared widowbirds do not provide parental care. In fact, the only resources males provide are potential nest sites in their territories. They are different from other Euplectes species in that the males use only a simple nest ring in courtship and the females build and position the actual nests. The nests are usually oval in shape and the females line the nests with grass. Females continue to add to the nest during the incubation. Old nests are often occupied by Zebra Waxbills. There are usually between 2 and 4 eggs in a clutch, each egg being greyish or blue-green, with brown speckles. The incubation period, done only by the female, is between 12 and 15 days. Females also do all of the feeding, primarily via regurgitation, during the nestling period for the offspring, which is between 14 and 17 days. The nests are commonly parasitized by Diederik Cuckoos.

Because they are offering no other gifts, it is very important for the males to establish an exclusive territory at the beginning of the breeding season to ensure successful mating. Males aggressively defend their territories from intruders. There is no difference in costs or benefits between females who choose unmated males, monogamy, and females who settle with mated males, polygyny. Females may gain indirect benefits of picking higher quality males by producing higher-quality offspring, without suffering costs of shared territories.

Sexual Ornaments
Tails
During prenuptial moulting, prior to the breeding season, the males replace their non-breeding feathers. Males that hold territory have shorter tails and carotenoid collars that are 40% larger than non breeding floating males . The red collar is for male-male competition, while female choice is based on tail length. Tail length is negatively correlated with carotenoid signal. Also, looking at body size and condition, this accounts for 55% of the variation in tail length. Body size may play a role in the variation of size and redness of both territorial and floater males. Female preference for long tails was first observed in long-tailed widowbirds, and then subsequently observed in Jackson’s widowbird and the red-collared widowbird.Tail length explains 47% of the male’s reproductive success, indicating the strength of this sexual ornament. Tail symmetry, however, does not have an effect on mating success. In the red-collared widowbird there is a strong trade-off between carotenoid coloration, which is an agonistic signal and tail length, which is an epigamic signal, directly attracting females. These are both costly ornaments that are maintained through multiple receivers.

Plumage
The red-collared widowbird has one of the highest measured plumage carotenoid concentrations in birds. There is a high presence of lutein and zeaxanthin in the feathers, which is consistent with their high dietary consumption of grass seeds. There is a carotenoid basis of ‘redness’ observed in the bird, and studies suggest that its color production is due to enzymatic conversion of dietary pigments into red keto-carotenoids, a costly process. The red collar functions as a dominance signal, which was supported experimentally through manipulation of the badges. The experiment showed that red-collared males dominated orange males, which in turn dominated brown and blue collared males. Furthermore, with additional manipulation of badges, males with enlarged red, enlarged orange, and reduced red collars obtained territories, while those with reduced orange and blackened or removed collars failed to establish or maintain territories. Lastly, males with reduced signals defended smaller territories, had more intruders, and spent more time, thus increased cost, on aggressive interactions. Collectively, these observations led to the conclusion that redness, and to a lesser degree size, indicate dominance status and fighting ability in male contests.

Fluctuating asymmetry is a population phenomenon of random deviation in a morphological trait. Some researchers think that fluctuating asymmetry reflect an indirect measure of fitness. This is because sexual ornaments are under intense directional selection. The sexual ornament displayed, the degree of fluctuating asymmetry, reflects the male’s ability to deal with environmental and genetic stress, thus as an observer, there is a compromise in males between tail length and symmetry. The tail length itself is the strongest predictor of mating success. However, when the tails were experimentally manipulated, comparing a shortened tail to the control, these males had equal success in acquiring territory with no difference in size or quality. The long-tailed controls spent less time flying and performing courtship displays and they attracted higher quality and more nesting females compared to short-tailed males.

Demonstrating the high cost of the long tail, the control birds with longer tails showed a more significant decline in condition, measured by relative body mass, compared to the birds with shorter tailed birds. Additionally, longer tails are aerodynamically costly, hindering flying ability by increasing drag. Both the short tailed and control residents have declined condition compared to the floaters, the males who did not establish territories, which suggests an interaction between tail lengths and there is high cost of territory acquisition, defense, and courtship displays.

Signals
To explain the existence of multiple handicap signals, multiple receiver hypothesis has been proposed. In an environment, rivals and mates potentially assess different signals, thus making more than one ornament maintain stable condition-dependent signals, reflecting different qualities or associated costs. These signals are maintained because they target different receivers and reflect different aspects of fitness. This is extended to explain increasing complexity of signals, where different receivers are receptive to different aspects of the same signal. In the case of the red-collared widowbird, the elongated tail addresses female choice, while the red carotenoid badge addresses aggressive male competition over territory.

Status
The Red-collared Widowbirds are not considered to be globally threatened. They have a very wide range and are found commonly in many regions. They can be found in Kruger National Park, located in South Africa, with a large population of an estimated 2000 individuals. Additionally, the species is found in South and Central Mozambique with approximately 11,000 individuals.

[Amoli]

Red-collared widowbird, Rietvlei

[Flutterby]

Redcollared Widowbird, Rietvlei

Male (breeding plumage)


Male and Female (non-breeding plumage)

[Lisbeth]

The Long-tailed Widowbird (Euplectes progne), also known as the “Sakabula,” is a species of bird in the Ploceidae family. The species are found in Angola, Botswana, the Democratic Republic of the Congo, Kenya, Lesotho, South Africa, Swaziland, Zambia, and southern Zaire. The Long-tailed Widowbird is a medium-sized bird and one of the most common in the territories it inhabits. Adult breeding males are almost entirely black with orange and white shoulders (epaulets), long, wide tails, and a bluish white bill. Females are rather inconspicuous, their feathers streaked tawny and black with pale patches on the chest, breast and back, narrow tail feathers, and horn-color bills.
When flying, male Long-tailed Widowbirds are readily visible due to their extremely long tails. Between six and eight of their twelve tail feathers are approximately half a metre (approximately 20 inches) long. The tail during flight display is expanded vertically into a deep, long keel below the male as he flies with slow wingbeats 0.5 to 2 metres (20 to 78 inches) above his territory.
Because of the seemingly large cost to such male ornaments, the Long-tailed Widowbird has been the subject of extensive research into the function and evolution of sexually selected traits. This research has demonstrated the existence of female choice in sexual selection and indicates the trade-offs between sexual appeal and physical constraints with regard to the evolution of sexual ornaments.

Taxonomy
The Long-tailed Widowbird was first described by Pieter Boddaert, a Dutch physician and naturalist, in 1783. The Long-tailed Widowbird is a member of the genus Euplectes, and therefore closely related to other species of Widowbirds and Bishops. The Long-tailed Widowbird is classified as a passerine bird in the weaver family, Ploceidae, named in 1758 by Carl Linnaeus in 1758.The Long-tailed Widowbird has several of the common morphological traits and dietary preferences of this family, including its rounded conical bill and feeding on seeds.

The Long-tailed Widowbird has three geographically differentiated subspecies. These include delamerei, found in the highlands of Kenya, delacouri, found in the Congo, Angola and Zambia, and progne, found in Botswana, South Africa, Swaziland and Lesotho. Some researchers have suggested the existence of Long-tailed Widowbird superspecies based on similarity in male nuptial plumage such as tail length, but this is the topic of some debate.

Location


A range map of the habitat of the long-tailed widowbird

There are three known isolated populations of Long-tailed Widowbirds. The first is found in the Kenyan highlands, the second in Angola, southern Zaire and Zambia, and the third in Southern Africa. It is unknown when these populations were last in contact, however, the central population differs most in morphology relative to the other two populations. The Southern African population extends from the Eastern Cape Providence through the Free State, Lesotho, Transkei, KwaZulu Natal, and western Swaziland to the Transvaal plateau. The species just enters southeastern Botswana, but is most commonly found in the central highveld of South Africa. The Long-tailed Widowbird can be found at elevations up to 2750 metres in the Drakensberg Mountains.

Habitat and diet
Long-tailed Widowbirds are generally found in swampy grassland in flocks consisting of one or two males and a number of females. The males fly with their tails drooping and somewhat spread, and with slow regular movements of their wings. In wet weather, they are unable to fly due to their elongated tails. During the non-breeding season, Long-tailed Widowbirds congregate into flocks, which can be found roosting in reed beds.

The Long-tailed Widowbird’s diet generally consists of seeds, supplemented occasionally by arthropods. The birds do most of their foraging in flocks on the ground, though they are occasionally observed hawking insects airily. The Long-tailed Widowbird feeds on a distinct variety of seeds, including those of Setaria sphacelata (Twisted-leaf bristle grass), Paspalum dilatatum (Common paspalum), Paspalum distichum (Couch paspalum), Pennisetum clandestinum (Kikuyu grass), Triticum (wheat), Themeda triandra (Rooigras), and Senecio juniperinus (groundsel). They also feed upon both insects, including species of beetles (Coleoptera), cicadas and aphids (Hemiptera), and spiders.

Morphology
Long-tailed Widowbirds showing breeding and non-breeding plumage
Long-tailed Widowbirds exhibit distinct sexual dimorphism. Males and females exhibit differences in behavior and morphological traits. Adult males are entirely black, including under their wing-covets. Males’ wing shoulders are orange red and their wing-covets white. Their bills are bluish white. Males are known for their distinctly long tails, which contain twelve tail feathers. Of these twelve tail feathers, between six and eight are approximately half a metre long. Males have wingspans of approximately 127 to 147 mm.

Females have a rather subdued coloration. The upper portion of the female’s body is streaked with buff or tawny and black. Female chests, breasts and flanks are slightly paler than their above coloring. The area under the wing-covets is black and the females’ tail feathers are narrow and pointed. Finally, their bills are horn-coloured.
Non-breeding males are slightly larger than females, though they demonstrate a remarkably similar appearance. For the most part, these males are colored in the same manner as the females, except in that they are more broadly streaked above and below and have wings and wing shoulders with the morphology of the breeding class of males. Rarely, males in the non-breeding class have elongated brownish black tail feathers, though these feathers are substantially shorter than those of the breeding class.

Immature males and females are very similar in appearance to the adult female. However, immature males, much like adult non-breeding males, are slightly larger than adult females.

Behavior
Breeding
Males defend territories in the grasslands the species inhabits. Females have a long nesting period and survey these territories and the males that inhabit them prior to mate selection. Breeding takes place from February to July, reaching its peak in March and April. Females weave nests, shaped in large dome structures with a lining of seedheads, in the high grass within males’ territories. The nests are placed 0.5–1 meters of the ground in the upper third of the high grass (Eleusine jaegeri), where the females raise their two to three young. Females often mate with the male within whose territories they nest. Females lay one to three eggs after mating. These eggs are pale bluish green and streaked with brown. These are usually around 23.5 millimeters by 16.5 mm in size.

Sexual selection
Charles Darwin first expressed his ideas on sexual selection and mate choice in his book The Descent of Man, and Selection in Relation to Sex in 1871 in response to questions surrounding the elaborate ornamentation that males of some species exhibit despite detrimental costs to survival and seemingly negative consequences for reproductive success. He proposed two explanations for such traits’ existences: these traits are useful in male-male combat or are preferred by females.

Relative to the first of Darwin’s theories on sexual selection, the process of female choice, though theoretically plausible, took a considerable amount of time to gain acceptance because Darwin had little, if any, firm evidence that females did in fact choose mate based on characteristics they found attractive. It took ninety years after Darwin’s initial proposal for the theory to be tested in what has become a classic example of Behavioral Ecology research.
The male Long-tailed Widowbird has one of the most remarkable ornaments among passerine birds. Their tails, which are often more than half a meter long, are the most extreme sexual ornament among Euplectes and seem to in fact be detrimental to the survival of the male. Thus, the tail appears to oppose forces of natural selection in the basic sense by decreasing survival in individuals who carry the trait. It was for this reason that researchers have chosen to focus their research into female choice on the confusing example of the Long-tailed Widowbird.

Andersson Experiment
Malte Andersson and colleagues tested Darwin’s (and Fisher’s) theory of female preference for ornamentation as the cause of extreme elongation of the male Long-tailed Widowbird’s tail. They changed the length of males’ tails and studied their relative mating success. Early in the breeding season, the territories of thirty-six males were mapped and the numbers of nests were counted. The experimenters used each male as his own control by subtracting the number of nests in each male’s territory before treatment from the total of nests after treatment. This reduced the influence of initial variation among male territories on the outcome of the experiment. In a randomized block experiment, the color-ringed males were partitioned among nine groups of four males each. These groups were similar in territory quality and tail length. The tail of one randomly selected male within each group was cut to about 14 centimeters in length. Each removed feather was then glued to the corresponding feather of another male, elongating his tail by 20 to 30 centimeters. The two other males in the group served as controls. One had his tail cut and repaired using glue, while the other’s tail was left unchanged.

A clear pattern of success emerged, with males with the elongated tails being the most successful, followed by the control (normal tail length) males, followed by the males with shortened tails. The result indicated that the long tail is favored by sexual selection through female choice of mates. Female preference for long tails is also seen in the Red-collared Widowbird.
The Andersson experiment demonstrated that female Long-tailed Widowbirds prefer supernormal tails, as males with elongated tails were found to be the most reproductively successful. Amazingly, the tail females found most attractive were longer than those that occur in the natural setting. This outcome was shown to be the result of female choice rather than differences in male behavior resulting from shortened tails: males with shortened tails neither became less active in courtship display, nor did they give up their breeding territories. Thus, the tail is used to attract females rather than in direct contests among males, which is further supported by the fact that males do not expand their tails during flight displays during territorial contests.

Males' tail and epaulet
One explanation for why females favor long tails in males is that the expanded tail enlarges the lateral surface area of the male by 2-3 times, making him much more visible from far distances over open grassland. However, this is most likely not the whole explanation, especially considering that prior to mating, females spend a great deal of time comparing males and, thus, do not rely on sighting them from a distance.

As of this time, the exact function of epaulet in male Long-tailed Widowbirds is unknown. But, its use does resemble that of the Red-Winged Blackbird, being displayed during courtship and threat displays. Thus, the two most conspicuous ornaments of the male birds in the two species may be favored by different forms of sexual selection: the tail of the Long-tailed Widowbird by female choice and the brightly colored epaulets of the Long-tailed Widowbird and Red-winged Blackbird by male contest competition.

Conservation status
The Long-tailed Widowbird has a very large range, and so the species would not be classified as Vulnerable under the range size criterion put forward by Bird Life International which include that the extent of occurrence being less than 20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation. The population is stable according to the population trend criterion, which requires a greater than 30% decline over ten years or three generations, and would not be considered Vulnerable for this reason. While the total population size has not yet been quantified, it is not believed that the Long-tailed Widowbird is approaching the threshold for being considered Vulnerable under the population size criterion (less than 10,000 mature individuals with a continuing decline estimated to be greater than 10% in ten years or three generations, or with a specified population structure). For these reasons, the species is evaluated as Least Concern.

[Amoli]

Long tailed widowbird, Rietvlei

[Flutterby]

Longtailed Widowbird, Rietvlei