A unifying framework for the transient parasite dynamics of migratory hosts

Migrations allow animals to track seasonal changes in resources, find mates, and avoid harsh climates, but these regular, long-distance movements also have implications for parasite dynamics and animal health. Migratory animals have been dubbed “superspreaders” of infection, but migration can also reduce parasite burdens within host populations via migratory escape from contaminated habitats and transmission hotspots, migratory recovery due to parasite mortality, and migratory culling of infected individuals. Here, we show that a single migratory host–macroparasite model can give rise to these different phenomena under different parametrizations, providing a unifying framework for a mechanistic understanding of the parasite dynamics of migratory animals. Importantly, our model includes the impact of parasite burden on host movement capability during migration, which can lead to “parasite-induced migratory stalling” due to a positive feedback between increasing parasite burdens and reduced movement. Our results provide general insight into the conditions leading to different health outcomes in migratory wildlife. Our approach lays the foundation for tactical models that can help understand, predict, and mitigate future changes of disease risk in migratory wildlife that may arise from shifting migratory patterns, loss of migratory behavior, or climate effects on parasite development, mortality, and transmission.

Analysis of Impacts of Land Use Changes in Kitengela Conservation Area on Migratory Wildlife of Nairobi National Park, Kenya

Nairobi National Park (NNP) in Kenya was established in 1946 to conserve the abundance and diversity of wildlife in the Kitengela-Athi-Kaputei plains, from excessive exploitation. It is currently fenced except on the Kitengela side across the Mbagathi River due to the sub-division of the group ranches, which commenced in the 1980s, limiting access of wildlife to the migratory corridor and dispersal areas. This paper is based on a study conducted to assess the impacts of the resultant land use changes in the Kitengela dispersal area/ migratory corridor on the migratory fauna of NNP, and to identify appropriate mitigation measures. The findings indicated that increased human settlement, led to changes in land uses which resulted into multiple negative impacts on the migratory wildlife of Nairobi National Park, mainly due to loss of dispersal area and blockage of migratory routes, leading to wildlife confinement, decreased wildlife tolerance and increased incidences of human wildlife conflicts. Data analysis indicated decline in migratory wildlife population thus negative effect (F=, 6.066, p<0.05). The findings also indicated that loss of migratory routes/dispersal area and reduced vegetation cover was regarded by 55% of the local community respondents as one of the main consequences of the land use changes resulting from the subdivision of the group ranches leading to decreased wildlife tolerance (β = 0.246) and wildlife confinement (β = 0.371) in NNP (p= 0.021, < 0.05, F= 2.678; R=0.179, R2= 0.032). The paper also discusses the mitigation measures for the longtime sustainability of the park, the dispersal area and migratory corridor, including holistic implementation of the Kitengela-Isinya-Kipeto Local Physical Development Plan, mapping and protection of the vital wildlife areas within the migratory range, including the wildebeest calving area in North Kaputiei.