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The Blue Swallow Hirundo atrocaerulea satisfies the population size criteria for regionally Critically Endangered (population numbers <250 individuals and a decline of at least 25% is predicted in the next three years).
The Blue Swallow is an African endemic and an intra-African migrant in sub-Saharan Africa (Keith et al. 1992). This bird breeds in South Africa, western Swaziland, eastern Zimbabwe, western Mozambique, Malawi, north-eastern Zambia, southern Tanzania and south-eastern Democratic Republic of the Congo from September to April (Turner and Rose 1989, Evans and Bouwman 2010a). During the non-breeding season (May to August), Blue Swallows migrate to western Kenya, southern Uganda, north-western Tanzania, and north-eastern Democratic Republic of the Congo (Turner and Rose 1989, Evans and Bouwman 2010a). In South Africa, the species is restricted to grasslands of the Eastern Escarpment. In KwaZulu-Natal, the northern and southern limits of the breeding range are Impendle and Harding respectively, with the majority of birds breeding in the Ixopo district. In Swaziland, all suitable Blue Swallow habitats are located along the western part of the country above 1 200 masl (Parker 1994, Monadjem et al. 2006). Recent confirmed breeding events occurred in Malolotja Nature Reserve, Sibebe Mountains, and Mahlangatsha (Parker 1994, Monadjem et al. 2003, Monadjem et al. 2006). The Blue Swallow's range in South Africa and Swaziland has contracted by 74% from 1890 to 2005 (Evans and Bouwman 2010a). Blue Swallows have disappeared from 21 of 29 known sites between 1880 and 1987 (Allan et al. 1997). By the end of the 1980s, the four pairs in Blinkwater Nature Reserve were locally extinct (Evans and Barnes 2000). In the 1990s, Blue Swallow pairs in the Blyde River Canyon Nature Reserve and along the Mac-Mac Escarpment had become locally extinct (Evans and Bouwman 2010a). By the end of the 2000s, the most recent local extinctions were the loss of two pairs in Misty Mountain Natural Heritage Site, the last two remaining pairs near Nongoma, in northern KwaZulu-Natal and nine pairs in the Blue Swallow Natural Heritage Site. The few pairs near Nongoma were the only Blue Swallows in the region occupying the Northern Zululand Mistbelt Grassland vegetation type.
The global population has been quantified at c. 2 000 mature individuals (Evans and Bouwman 2010b). In 2000, there were estimated to be a maximum of 240 mature individuals within the region (Evans and Barnes 2000). Only four nests are known from Mpumalanga and approximately 16 and 33 in Swaziland and KwaZulu-Natal, respectively (IT Little pers. comm.). The regional population is estimated at 53 pairs or 106 mature individuals. Confidence in this regional population estimate is high.
The global population is in decline (BirdLife International 2014) with the regional population showing a similar trend, decreasing by 52.4% over the past three generations (2000 to 2011). It is believed that this decline is continuous and will be greater than 25% within one generation length (3 years). Confidence in this regional trend estimate is high.
The highest priority threats, resulting in habitat degradation and conversion, are afforestation, large-scale and subsistence agriculture, invasion by alien eucalyptus, pine and wattle trees, (Allan et al. 1987, Wakelin and Hill 2007), rural population growth, and inappropriate management and drainage of wetlands (Evans et al. 2002, Evans 2010). Inappropriate farming methods lead to soil erosion (Monadjem et al. 2003). The drainage of wetlands for cultivation and road construction remains a serious threat (Evans 1996, 2008, Evans and Bouwman 2010) while mining represents a threat of moderate to high importance (Kemper and Niemand 1992, Evans 1996, 2008). Overgrazing and overburning, which reduces substrate for insects upon which Blue Swallows feed, are threats (A Marchant pers. comm.).
The process of sinkhole formation, upon which Blue Swallows rely on for nesting sites, may be negatively affected by timber forests drying out underground streams (Snell 1969). Fragmentation of grasslands, as a result of grassland transformation, may result in Aardvark Orycteropus afer not getting to potentially suitable sites to dig holes that can be used by the birds. The snaring of Aardvark has led to a decline in local populations (Marchant 2012), thereby also influencing the number of holes available for the birds. Tarboton (1992) demonstrated the importance of sufficient altitudinal range over which to forage during mist periods for the survival of Blue Swallows near Graskop. The loss of foraging habitat at lower elevations that were less often enveloped in mist, as compared to the higher-altitude breeding and foraging habitat, results in the birds being unable to find sufficient food and prolonged poor weather conditions adversely affecting breeding success (Evans and Bouwman 2010a). Uncoordinated small-scale ecotourism developments have resulted in loss of Blue Swallow nesting sites in South Africa (Evans 1997). In areas where Blue Swallows coexist in proximity to agricultural crops, the use of insecticides may affect aerial insect prey availability to Blue Swallows (Evans et al. 2002).
As a migrant species, Blue Swallow populations are not only affected by threats on their breeding grounds in South Africa and Swaziland, but also on their migratory routes and in their non-breeding range in Uganda (Evans and Bouwman 2010a, Wakelin et al. 2011). Swallows migrate by day and feed en route (Turner and Rose 1989). A loss of habitat along their migratory routes may result in there being less food available to the birds on migration, resulting in an increase in mortality of these birds, and, in turn, resulting in fewer birds returning to South Africa and Swaziland to breed. In addition, a reduction of habitat suitable for Blue Swallows in their non-breeding range would result in an increase in mortality and fewer birds returning to breed (Evans et al. 2002). A lesser threat is competition for nest holes between Banded Martin and Blue Swallow, which may become more relevant as the habitat shrinks and nest holes become fewer (A Marchant pers. comm.).
An International Action Plan and South African Population and Habitat Viability Assessment (PHVA) was completed for the Blue Swallow in 2002 (Evans et al. 2002). Over the past 10 years, research into the extent of the decline of the Blue Swallow population in South Africa, and further afield in Africa, has been completed (Evans and Bouwman 2010a). Research into the habitat requirements of Blue Swallows in South Africa has also been conducted (Wakelin 2006, Evans and Bouwman 2010a). Initial research into the migratory linkages between Blue Swallows' breeding and non-breeding ranges has been undertaken (Evans and Bouwman 2010b, Wakelin et al. 2011) although certain aspects, including stop-over sites, still need to be investigated.
There are several stakeholders involved in Blue Swallow conservation. Ezemvelo KwaZulu-Natal Wildlife is mandated by the KwaZulu-Natal provincial government to coordinate efforts to protect this species and does so through a provincial Blue Swallow Monitoring Programme. The Blue Swallow Working Group of the Endangered Wildlife Trust, now part of the Threatened Grassland Species Programme, contributes to the development of conservation policy, legislation and advocacy for the protection of threatened grassland species including the Blue Swallow. The group also undertakes research and monitoring into the habitat requirements and population trends of the species, education and awareness campaigns.
All localities known to contain breeding Blue Swallows in South Africa are designated as Important Bird Areas (Barnes 1998). The Blue Swallow is listed in Appendix I and II of the Convention on the Conservation of Migratory Species. It is listed under Schedule 2: Specially Protected Wild Animal under the Limpopo Environmental Management Act No 7 of 2003. The Blue Swallow is listed as Critically Endangered in Swaziland and is protected by the Swaziland Game Act (Monadjem et al. 2003).
Conservation of both the breeding and non-breeding range of the Blue Swallow population in South Africa and Swaziland is crucial. Several priority actions, which were identified by Ezemvelo KwaZulu-Natal Wildlife, include:
In addition, Ezemvelo KwaZulu-Natal Wildlife have set the following targets to be achieved from these actions: 1) increasing and securing the KwaZulu-Natal Blue Swallow population to 80 active nests; 2) and achieving an average fledgling success rate of two per breeding event per year. The long-term objectives are to rehabilitate and secure the breeding population of Blue Swallow in KwaZulu-Natal to 156 active breeding pairs with an average fledgling success rate of two per breeding event per year (Marchant 2012). In addition, Ezemvelo KwaZulu-Natal Wildlife has compiled a monitoring plan for Blue Swallow in the province (Marchant 2012) which should be used to update applicable sections of the International Blue Swallow Action Plan and the Population and Habitat Viability Assessment. Based on these documents a Biodiversity Management Plan must be developed for submission to the South African Department of Environmental Affairs which will provide greater legal support to the provincial conservation authorities and other institutions in their efforts to conserve the Blue Swallow and its habitat.
The monitoring programme as set out in the Ezemvelo KwaZulu-Natal Wildlife Blue Swallow Monitoring Programme needs to be implemented. This programme will include annual assessments of the number of active nests in KwaZulu-Natal, the number of breeding events per nest, and the number of chicks fledged per breeding event. Additional research priorities include:
* Further research is needed to confirm where the regional breeding population migrates to during the austral winter.
* The importance of wetlands as foraging habitat for Blue Swallow needs to be evaluated.
* The importance of grassland corridors and their role in connecting habitat patches needs to be investigated.
* The impact of the use of pesticides in areas where Blue Swallows exist needs to be determined.