Current conservation status of the Blue Swallow Hirundo atrocaerulea Sundevall 1850 in Africa

The global Blue Swallow Hirundo atrocaerulea was classified as Vulnerable in 2010 on account of its small and rapidly declining population estimated at less than 1 500 pairs. We undertook this study to gain a better understanding of the current status and threats facing this migratory species. Three previously unknown areas that might be part of the species’ non-breeding range were identified in Kenya and northern Tanzania. Within its breeding range we identified three previously unknown areas of potentially suitable habitat, one in Tanzania and two in Malawi, which require further exploration. Population viability assessment predicted that the Blue Swallow population will decline by 8% in 10 years. The overall probability of extinction of the species in the wild is 3%. Minimum viable population size analysis suggests that a goal for the long-term conservation of the Blue Swallow should be to mitigate current threats that are driving declines such that the population increases to a minimum of 3 600 individuals. This should consist of at least 900 individuals in each of the four clusters identified, along with a minimum of 500 individuals in at least one of the meta-populations per cluster. The four clusters are located in (1) the southeasten Democratic Republic of the Congo, (2) highlands of southern Tanzania and northern Malawi, (3) eastern highlands of Zimbabwe and (4) South Africa and Swaziland. The current proportions of the Blue Swallow population in strictly protected and unprotected areas on their breeding grounds are 53% and 47%, respectively, whereas on their non-breeding grounds the corresponding percentages are 25% and 75%, respectively. Our reassessment of the Blue Swallow’s risk of extinction indicates that it continues to qualify as Vulnerable according to the IUCN/SSC criteria C2a(i).http://www.tandfonline.com/loi/tost202016-09-30hb2016Zoology and Entomolog

Vegetation composition and structure influences bird species community assemblages in the highland agricultural landscape of Nyandarua, Kenya

We examined the effects of vegetation composition and structure on bird species diversity and richness of foraging guilds in the highland agricultural landscape of Nyandarua, Kenya. Bird point counts and vegetation surveys were undertaken during four sampling periods. Linear mixed models were used to examine the effects of vegetation variables on bird species diversity and richness of respective foraging guilds, and logistic generalised linear models used to examine vegetation effects on the presence/absence of the 17 most common bird species. Bird species diversity increased with increasing density of woody plant species and vegetation structural heterogeneity. Two gradients of increasing vegetation structural heterogeneity were most important in influencing bird community composition and had positive effects on species diversity and the presence of most of the species assessed: (1) increasing closed cover due to woody plant density, which also had positive effects on species richness of frugivores and nectarivores, but negative effects on carnivores, and (2) increasing fallow and cultivation versus decreasing grassland/pasture cover, which also had a positive effect on species richness of granivores and omnivores. This study reaffirms the need to maintain a structurally rich agricultural landscape for it to support agrobiodiversity.Keywords: birds, East Africa, farmland, forest, grassland, heterogeneityOSTRICH 2013, 84(3): 171–17

Effects of crop diversity on bird species richness and abundance in a highland East African agricultural landscape

We examined the effects of crop diversity on avian species richness and abundance in the highland farmlands of Nyandarua, Kenya. We surveyed birds using point counts and recorded habitat data at the same locations estimating cover and growth stage of all crop types, whether they were grown as intercrops or monocrops, and the dominant surrounding vegetation type. An index of crop diversity was calculated from the percentage cover of the different crop types. The effects of these habitat variables on bird species richness, abundance of foraging guilds and the abundance of each of the 12 most common species were examined using linear mixed models. Crop diversity had significant positive effects on species richness. Cereal cover had negative effects on species richness, overall bird abundance and abundance of granivores. Occurrence of cultivation/fallow and mixed vegetation as the dominant habitat surrounding crop plots positively influenced granivores’ abundance, and the abundance of Speckled Mousebird Colius striatus, a pest species, was favoured by increasing orchard cover and occurrence of wooded and shrub vegetation as the dominant surrounding vegetation type. The study confirmed that heterogeneity brought about by increased crop diversity and reduced cereal cover within cultivations contributed to enhancement of farmlands as habitats for birds.Keywords: crop diversity, farmland, heterogeneity, Kenya, species richnessOSTRICH 2013, 84(1): 33–3