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Microfilariae Were Far More Common in Male Village Weavers, With Prevalence Highest Mid-Morning

Village weavers at a nesting colony in Phinda Private Game Reserve
Research · Disease, parasites & microbiology

Breeding village weavers (Ploceus cucullatus) in Amurum Forest Reserve, Nigeria, showed a strong sex difference in microfilariae infection, and the infection pattern also changed over the course of the morning. Microfilariae are larval stages of filarial nematodes that circulate in the blood and are transmitted between hosts by blood-feeding vectors. The study, first published online on 28 January 2026, also compared body mass between infected and uninfected birds as an indicator of body condition.

Mist nets are fine mesh nets stretched between supports to temporarily capture flying birds so they can be handled, measured or sampled.

During the May–August 2023 breeding period, researchers captured 124 adults — 72 males and 52 females — with mist nets. Sampling was divided into early morning (06:30–07:59), mid-morning (08:00–09:29) and late morning (09:30–10:30). Blood was examined with the buffy coat method for motile microfilariae, and parasites were counted in infected birds to compare infection intensity.

Males were infected far more often

The strongest pattern was the difference between the sexes. Microfilariae were detected in 68 of 72 males (94.4%) but only 16 of 52 females (30.8%). Males also carried higher parasite loads among infected birds. Both infection prevalence and intensity peaked in mid-morning, especially in males.

Body mass patterns differed between sexes

Body mass showed another sex-specific pattern. Infected males were heavier on average than uninfected males in all three sampling periods, with the largest difference in mid-morning. The authors interpret this as a possible life-history trade-off: males in better apparent condition may continue investing heavily in reproductive traits and activity while carrying substantial parasite burdens, rather than higher body mass necessarily indicating stronger resistance to infection. The study did not directly test that mechanism.

Females showed the opposite association later in the morning. Infected and uninfected females had similar body mass early in the morning, but infected females were lighter than uninfected females in the mid- and late-morning comparisons. Across the morning, uninfected females gained mass steadily, whereas infected females showed a mid-morning dip followed by partial recovery. The authors suggest that energetic costs of infection and altered activity could contribute to this pattern, but these explanations were not tested directly.

Sampling time matters

The results also matter for field sampling. The authors had expected early-morning trapping to favour uninfected, more active birds, but both prevalence and intensity instead peaked in mid-morning, especially in males. They discuss host activity and the timing of blood-feeding vectors as possible contributors. Because the infection pattern changed over only a few hours, surveys conducted at a single time of day can produce different pictures of filarial prevalence and intensity.

Sources and image credit

  1. Andong, F. A., Ejere, V. C., Mayowa, E. S., Agyo, R. A., & Afyare, A. A. A. (2026). Within-morning dynamics of filarial infection in breeding village weavers (Ploceus cucullatus): Sex-biased patterns and implications for host condition. Avian Biology Research, 19(2), 35–41.Primary peer-reviewed research article, first published online 28 January 2026. The study sampled 124 breeding adult village weavers (72 males and 52 females) in Amurum Forest Reserve, Nigeria; microfilariae were detected in 94.4% of males and 30.8% of females, and prevalence and intensity peaked in mid-morning.

Image: Charles J. Sharp — village weavers at a nesting colony in Phinda Private Game Reserve, South Africa, 24 October 2014; representative breeding-colony image, not birds from the microfilariae study in Amurum Forest Reserve, Nigeria. Source: Wikimedia Commons. · CC BY-SA 4.0 · Source

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