The red-collared widowbird (Euplectes ardens) is a species of bird in the family Ploceidae. 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 of 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. The red-collared widowbirds are not considered to be globally threatened. They have a very wide range and are found commonly in many regions.
Similar to other widowbirds, male red-collared widowbirds have both seasonal and sexual dimorphism. Males are about 9.8 inches in length while females are only about 11 inches. 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 8.6 inches, and crescent-shaped carotenoid based chest patch. 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 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 1.5 inches. Nonbreeding males, however, retain their black tails, while females and subadults' tails are dark-brown.
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. 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 nonbreeding 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. 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.
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.
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 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.
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.
