Spring reproductive success influences autumnal malarial load in a passerine bird

Although avian haemosporidian parasites are widely used as model organisms to study fundamental questions in evolutionary and behavorial ecology of host-parasite inter- actions, some of their basic characteristics, such as seasonal variations in within-host density, are still mostly unknown. In addition, their interplay with host reproductive suc- cess in the wild seems to depend on the interaction of many factors, starting with host and parasite species and the temporal scale under study. Here, we monitored the par- asitemia of two haemosporidian parasites – Plasmodium relictum (lineage SGS1) and P. homonucleophilum (lineage SW2) – in two wild populations of great tits (Parus major) in Switzerland over three years, to characterize their dynamics. We also collected data on birds’ reproductive output – laying date, clutch size, fledging success – to determine whether they were associated with parasitemia before (winter), during (spring) and after (autumn) breeding season. Parasitemia of both species dramatically increased in spring, in a way that was correlated to parasitemia in winter. Parasitemia before and during breeding season did not explain reproductive success. However, the birds which fledged the more chicks had higher parasitemia in autumn, which was not associated with their parasitemia in previous spring. Our results tend to indicate that high haemosporidian parasite loads do not impair reproduction in great tits, but high resource allocation into reproduction can leave birds less able to maintain low parasitemia over the following months

Habitat preferences of the Ortolan Bunting ( Emberiza hortulana ) in its prime wintering grounds, the cereal‐dominated Ethiopian Highlands

Abstract Agricultural intensification and land-use changes are major factors impacting farmland biodiversity. The Ortolan Bunting Emberiza hortulana is the long-distance trans-Saharan migratory passerine that has undergone the most dramatic decline among all European farmland birds. The factors responsible for this decline may originate from the breeding grounds, migration stopovers and/or overwintering quarters. Very little is known about conditions on the species' wintering grounds, but a recent study has highlighted the utmost importance of the traditionally managed agroecosystems in the Ethiopian Highlands as a key wintering area, apparently harbouring as much as 90% of the world's Ortolan Bunting population. Using radiotracking and line transect surveys, this study aimed to provide fine-grained information about species–habitat relationships in the Ortolan Bunting overwintering quarters. Our results showed the importance, at the landscape scale, of small-scale agriculture, notably of traditionally managed, cereal-dominated fields interspersed with semi-natural structures. At a foraging-site scale, on the other hand, patches of bare ground in combination with large areas of post-harvesting stubble represented key habitat features. Stubbles provide an essential food resource and bare ground promotes ground foraging by enhancing food accessibility. The maintenance of a traditional agricultural economy will be essential to maintain the habitat potential for the Ortolan Buntings overwintering in the Ethiopian Highlands and will be instrumental in preserving its world population from further decline

High semi‐natural vegetation cover and heterogeneity of field sizes promote bird beta‐diversity at larger scales in Ethiopian Highlands

1. The intensification of farming practices exerts detrimental effects on biodiver- sity. Most research has focused on declines in species richness at local scales (alpha-diversity) although species loss is exacerbated by biotic homogenization that operates at larger scales (i.e. affecting beta-diversity). The majority of stud- ies have been conducted in temperate, industrialized countries while tropical areas remain poorly studied. Agricultural landscapes of sub-Saharan Africa are still largely dominated by small-scale subsistence farming, but strenuous efforts to intensify farming practices are currently spreading to meet a growing food demand. It is therefore crucial to understand how these intensified practices affect biodiversity to mitigate their negative impacts. 2. We investigated how farming system (small- vs. large-scale farming) and land- scape complexity (semi-natural vegetation cover) drive bird species composi- tion, community turnover and beta-diversity patterns in Ethiopian Highlands' agroecosystems. We evaluated the following hypotheses: (1) large-scale farm- ing homogenizes bird communities, (2) community turnover is higher in small- scale farms, (3) interactive effects between landscape complexity and farming systems shape avian communities and (4) heterogeneity of field sizes increases community turnover at larger scales. 3. Bird communities underwent greater compositional changes along the land- scape complexity than along the agricultural intensity gradient. Contrary to our expectations, beta-diversity was not significantly lower within large-scale farms (no biotic homogenization), and complex landscapes that still offer a high amount of semi-natural vegetation promoted community turnover in both farm- ing systems. 4. Semi-natural vegetation cover mediated how avian communities responded to agricultural intensification: the compositional differences between small- and large-scale farms increased with vegetation cover, further promoting avian com- munity heterogeneity at the landscape level. 5. The heterogeneity in field sizes also enhanced bird community turnover, sug- gesting that a combination of both small- and large-scale farming systems within a given landscape unit would promote beta-diversity at larger scales, provided large-scale farms do not become dominant. 6. Synthesis and applications. Landscape complexity shaped avian communities to a stronger degree than farming intensity, emphasizing the importance of semi- natural vegetation and landscape heterogeneity for the maintenance of diverse bird communities and for achieving multifunctional landscapes promoting biodi- versity and associated ecosystem services on the High Ethiopian plateaus

Large-scale versus small-scale agriculture: Disentangling the relative effects of the farming system and semi-natural habitats on birds' habitat preferences in the Ethiopian highlands

https://authors.elsevier.com/c/1a56WcA-IZqL