From Mosquitoes to Birds: Unravelling the Role of Avian Hosts in Vector-Borne Pathogen Dynamics

TY - THES

T1 - From Mosquitoes to Birds

T2 - Unravelling the Role of Avian Hosts in Vector-Borne Pathogen Dynamics

AU - van Irsel, Jurrian

N1 - Data archiving: no data, PhD thesis

PY - 2026/1/15

Y1 - 2026/1/15

N2 - This thesis examines how vector-borne pathogens (VBPs) are emerging and spreading in increasingly urbanized environments, and how these changes affect wild bird populations. Early detection and surveillance are shown to be essential for managing risks to wildlife, domestic animals, and humans. Using public reports of dead birds, chapter 2 demonstrates that citizen-science data can effectively track pathogen emergence. The mosquito-borne virus USUV spread rapidly across the Netherlands, moving from the southeast to the north within three years and causing a 30% decline in Blackbird populations. Such data proved valuable for modelling transmission dynamics and linking pathogen pressure to wildlife population declines. Chapter 3 extends these findings by showing that other resident or short-distance migratory species, Song Thrush, Dunnock, Eurasian Wren, and Eurasian Robin, also experienced population declines associated with USUV. Long-distance migrants were unaffected, suggesting they play a limited role in year-round VBP transmission. Chapters 4 and 5 explore why resident birds may be key contributors to pathogen maintenance. Movement analyses revealed substantial spatial mixing: juveniles dispersed widely, while adults frequently moved between urban and non-urban habitats, likely tracking seasonal resources. These movements can expose urban populations to new pathogens and shape local transmission patterns. Finally, the thesis investigates how urban environments affect host immunity. Adult Blackbirds showed altered immune profiles in urban areas, potentially reflecting upregulated defences in response to urban stressors. No such patterns were found in nestlings, and no trade-offs between body condition and immunity were detected. Overall, this work highlights how urbanization, bird movement, and immune responses interact to influence VBP transmission. It underscores the importance of continued surveillance and offers insights for both public health and avian conservation.

AB - This thesis examines how vector-borne pathogens (VBPs) are emerging and spreading in increasingly urbanized environments, and how these changes affect wild bird populations. Early detection and surveillance are shown to be essential for managing risks to wildlife, domestic animals, and humans. Using public reports of dead birds, chapter 2 demonstrates that citizen-science data can effectively track pathogen emergence. The mosquito-borne virus USUV spread rapidly across the Netherlands, moving from the southeast to the north within three years and causing a 30% decline in Blackbird populations. Such data proved valuable for modelling transmission dynamics and linking pathogen pressure to wildlife population declines. Chapter 3 extends these findings by showing that other resident or short-distance migratory species, Song Thrush, Dunnock, Eurasian Wren, and Eurasian Robin, also experienced population declines associated with USUV. Long-distance migrants were unaffected, suggesting they play a limited role in year-round VBP transmission. Chapters 4 and 5 explore why resident birds may be key contributors to pathogen maintenance. Movement analyses revealed substantial spatial mixing: juveniles dispersed widely, while adults frequently moved between urban and non-urban habitats, likely tracking seasonal resources. These movements can expose urban populations to new pathogens and shape local transmission patterns. Finally, the thesis investigates how urban environments affect host immunity. Adult Blackbirds showed altered immune profiles in urban areas, potentially reflecting upregulated defences in response to urban stressors. No such patterns were found in nestlings, and no trade-offs between body condition and immunity were detected. Overall, this work highlights how urbanization, bird movement, and immune responses interact to influence VBP transmission. It underscores the importance of continued surveillance and offers insights for both public health and avian conservation.

M3 - PhD thesis

SN - 9789465229218

T3 - NIOO thesis 234

PB - Radboud University

CY - Nijmegen

ER -