Brazza's martin

Taxonomy

The Brazza's martin was first described in 1886 under its current binomial name by French zoologist Émile Oustalet from a specimen obtained at Nganchu in the Ngabé District of what is now the Republic of Congo. The genus name, Phedina, is derived from the Greek phaios (φαιός) "brown" and the Italian rondine "swallow". The species name commemorates Italian-born French explorer Pierre Savorgnan de Brazza, later to become governor-general of the French Congo, who collected the type specimen. This species was often called the "Congo martin", but this invites confusion with the Congo sand martin or Congo martin, Riparia congica.

The Phedina species are members of the swallow family of birds, and are classed as members of the Hirundininae subfamily, which comprises all swallows and martins except the very distinctive river martins. DNA sequence studies suggest that there are three major groupings within the Hirundininae, broadly correlating with the type of nest built. These groups are the "core martins", including burrowing species like the sand martin; the "nest-adopters", which are birds like the tree swallow that utilise natural cavities; and the "mud nest builders", such as the barn swallow, which build a nest from mud. The Phedina species nest in burrows and therefore belong to the "core martins" group.

The genus Phedina is thought to be an early offshoot from the main swallow lineage, although the striped plumage of its two species suggests a distant relationship with several streaked African Hirundo species. The only other member of the genus is the Mascarene martin P. borbonica, although in the past it has sometimes been suggested that Brazza's martin should be moved to its own genus Phedinopsis due to the significant differences in vocalisations and nest type from its relative. The nearest relative of the Phedina martins is the banded martin, Riparia cincta, which appears not to be closely related to the other members of its current genus and resembles Brazza's martin in nesting habits and vocalisations. The current Association of European Rarities Committees (AERC)-recommended practice is to move the banded martin to its own genus as Neophedina cincta, rather than to merge it into Phedina, since the banded martin's larger size, different bill and nostril shape and non-colonial nesting are differences from the other Phedina species.

Description

The Brazza's martin is 12 cm (4.25 in) long with wings averaging 100.5 mm (4.4 in). This small hirundine has grey-brown upperparts with a somewhat darker brown head and white underparts heavily streaked with blackish-brown from the throat to vent. There is a brownish tint to the breast plumage. The square tail averages 46.8 mm (1.8 in) long and has white edges to the brown undertail coverts. The flight feathers are blackish-brown and the bill and legs are black. The eyes are dark brown and the black bill averages 8.5 mm (0.33 in) long. The sexes are similar, but juvenile birds have more diffuse breast streaking and reddish-brown or buff edges to the feathers of the back and wings. This bird has no subspecies.

The song consists of a series of short notes increasing in frequency which are followed by a complex buzz and sometimes completed by a number of clicks. The song becomes increasingly loud, although the final clicks are quite soft. The song is similar to that of the banded martin, and does not resemble the Mascarene martin, suggesting unresolved taxonomic problems. The flight is variously described as heavy, or like that of a sand martin.

Brazza's martin can be distinguished from most other swallows within its range by the heavy streaking on the underparts. Although the lesser striped swallow also has white underparts with dark streaking, it is larger, has a deeply forked tail and a very different plumage, with dark blue upperparts, a red rump and a chestnut head. Compared to the Mascarene martin, this species is smaller, has a plainer back and finer dashing on the throat and chest, but there is no range overlap.

Distribution and habitat

The distribution of the Brazza's martin was initially poorly known, and until 1922 the type specimen in the Paris Museum was the only recorded example of this species. A Father Callewaert then collected 20 martins near Luluabourg (now Kananga), and this bird is now known to breed in the south of the Democratic Republic of the Congo (DRC), the Republic of the Congo, and in northern Angola. There is one probable sighting from southeast Gabon.

In the breeding season this martin is found near rivers with the steep banks that are needed for the nest burrows. Suitable habitat occurs along lowland tropical rivers like the Congo or rivers with sandbanks in the highlands of Angola. The highland locations have wide grassy riverways running through miombo woodlands, whereas the Congo Basin is tropical forest with over 200 cm (80 in) of rain a year. The lowland habitats are a patchwork of dry, seasonally flooded and permanently wet woodland, and seasonally flooded savanna, and the swamp forests contain trees such as Symphonia globulifera, raffia palms and Mitragyna species, and the riverbanks are often lined with arrowroot. This martin seems to be able to adapt to open savanna habitats containing Hymenocardia acida, in which it will roost overnight when not breeding, and is therefore not heavily dependent on the neighbouring forests as long as the riverine breeding sites survive.

Behaviour

In a presumed example of courtship behaviour, a male Brazza's martin perched about 30 cm (1 ft) away from a female and sang for about ten minutes. As it sang, the male leant towards the female, which caused the still-folded wings and tail to rise relative to the body. The Brazza's martin nests in the vertical banks of forested rivers from July to October, at the end of the dry season but before the river levels are high enough to cause flooding. A small colony of four pairs was recorded breeding near a rocky outcrop on the side of a valley.

The Brazza's martin nests singly or in loose colonies with sometimes widely separated burrows. The nest is a small heap of soft material such as feathers or dry grass at the end of a typically 50-cm (20-in) tunnel. The normal clutch is three white eggs. The eggs measure 18.5 x 112.5 mm (0.73 x 0.49 in) and weigh 1.5 g (0.05 oz). The incubation and fledging times are unknown, although as with all hirundines the chicks are altricial, hatching naked and blind.

As with other swallows, Brazza's martin feeds on flying insects, including termites, and may hunt over rivers or open savanna. It can occur in single-species flocks or with other swallows including barn swallows, lesser striped swallows, or rock martins.

Status

There has been little ornithological research in this part of Africa, and until 2008 the Brazza's martin was classified as Data Deficient. It was thought to have a much more restricted distribution range, but a 2007 paper presented evidence that extended its known range by 500 km (300 mi) to the north and 175 km (90 mi) southwards, a quadrupling of the area. It has a large range of 402,000  km² (155,000 sq mi) although the total population is unknown. Its extensive range and apparently stable population means this bird is classed as Least Concern on the IUCN Red List.

It is likely that this species is dug out for food by humans, but its small, dispersed colonies in firm soil suggests that it is a less rewarding target than the densely packed sandbank nests of species such as the African river martin and rosy bee-eater. Breeding colonies in river sandbars are liable to flooding, but neither natural causes nor hunting appear to be having a serious impact, and this species seems under no immediate threat. Its ability to use degraded habitats also aids its survival. The Brazza's martin is not a protected species in Angola, the DRC, or the Republic of Congo.

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