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23 May 2022 Dynamic occupancy models reveal Black-billed and Yellow-billed Cuckoos have high rates of turnover during the breeding season
Claire A. Johnson, Thomas J. Benson
Author Affiliations +
Abstract

Understanding the conservation needs of rare and hard-to-detect species becomes even more difficult when a species is highly mobile. Black-billed Cuckoos (Coccyzus erythropthalmus) and Yellow-billed Cuckoos (Coccyzus americanus) have experienced extensive range-wide population declines over the last several decades. Low detection probability has made it hard to determine causes of declines and resulted in poorly supported population and trend estimates. However, given evidence that cuckoos make wide-ranging movements during the breeding season, it may be necessary to address issues of both low vocalization rate and availability for detection to better understand these cryptic species. We performed passive and call-broadcast surveys for cuckoos at 41 sites across northern Illinois in 2019 and 2020. We examined the influence of call broadcast and temporal and environmental covariates on detection probability and how habitat covariates affected occupancy, immigration, and emigration both within and among sites. Individual detection probability increased substantially using call broadcasts (12 and 6 times for Black-billed and Yellow-billed Cuckoos, respectively) and detection increased with temperature. Black-billed Cuckoo detection probability also varied temporally, being lowest in the middle of the breeding season. We found strong support for turnover within sites during the breeding season, indicating maintenance of large home ranges, as well as among sites (average emigration probability of 86% and 47% for Black-billed and Yellow-billed Cuckoos, respectively). Black-billed Cuckoos were more likely to use open, shrubby sites and Yellow-billed Cuckoos to use sites with older successional habitat. While turnover rate was affected by habitat covariates, these species' reliance on ephemeral insect abundance may ultimately be driving occupancy dynamics. Our results suggest that broadcasts are essential for effectively monitoring these cuckoos, but also imply the need to move towards coordinating management at broader spatial scales for these highly mobile species.

LAY SUMMARY

  • Black-billed Cuckoos and Yellow-billed Cuckoos have experienced significant, range-wide declines, but are secretive and call infrequently, making them difficult species to study.

  • Broadcasting species calls, which often elicits responses from individuals that are present, can help with detection, but low detection could also be caused by cuckoos moving between repeat surveys.

  • We performed passive and broadcast surveys for cuckoos across northern Illinois in 2019 and 2020 to determine the importance of survey type, how detection changes seasonally and based on environmental conditions, and the frequency of turnover within and among sites.

  • Broadcasts and temperature substantially increased detection for both cuckoos. We also found support for high rates of turnover at both scales during the breeding season.

  • These results improve our ability to monitor cuckoos, but also imply the need to coordinate management activities across sites to manage for these cryptic, highly mobile species.

Entender las necesidades de conservación de especies raras y difíciles de detectar se vuelve aún más difícil cuando una especie es muy móvil. Coccyzus erythropthalmus y C. americanus han experimentado amplias disminuciones poblacionales en toda su área de distribución durante las últimas décadas. La baja probabilidad de detección ha dificultado determinar las causas de las disminuciones y ha dado lugar a estimaciones débiles de las poblaciones y sus tendencias. Sin embargo, dada la evidencia de que Coccyzus realiza movimientos de gran alcance durante la temporada reproductiva, puede ser necesario abordar los problemas de baja tasa de vocalización y baja disponibilidad para la detección para comprender mejor a estas especies crípticas. Realizamos muestreos pasivos y reproducción de llamadas para las especies de Coccyzus en 41 sitios a lo largo del norte de Illinois en 2019 y 2020. Examinamos la influencia de la reproducción de llamadas y de las covariables temporales y ambientales en la probabilidad de detección y cómo las covariables del hábitat afectaron la ocupación, la inmigración y la emigración tanto dentro como entre sitios. La probabilidad de detección individual aumentó sustancialmente usando reproducciones de llamadas (12 y 6 veces para C. erythropthalmus y C. americanus, respectivamente) y la detección aumentó con la temperatura. La probabilidad de detección de C. erythropthalmus también varió temporalmente, siendo más baja en la mitad de la temporada reproductiva. Encontramos un fuerte apoyo para el recambio dentro de los sitios durante la temporada reproductiva, indicando el mantenimiento de grandes rangos de hogar, así como entre sitios (probabilidad de emigración promedio de 86% y 47% para C. erythropthalmus y C. americanus, respectivamente). C. erythropthalmus fue más propenso a usar sitios abiertos con arbustos y C. americanus a usar sitios con hábitats sucesionales más viejos. Si bien la tasa de recambio se vio afectada por las covariables del hábitat, la dependencia de estas especies de la abundancia de insectos efímeros puede, en última instancia, estar impulsando la dinámica de ocupación. Nuestros resultados sugieren que las reproducciones de llamadas son esenciales para monitorear de manera efectiva a estas especies de Coccyzus, pero también implican la necesidad de avanzar hacia un manejo coordinado a escalas espaciales más amplias para estas especies altamente móviles.

Copyright © American Ornithological Society 2022. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.
Claire A. Johnson and Thomas J. Benson "Dynamic occupancy models reveal Black-billed and Yellow-billed Cuckoos have high rates of turnover during the breeding season," Ornithological Applications 124(3), 1-13, (23 May 2022). https://doi.org/10.1093/ornithapp/duac021
Received: 21 December 2021; Accepted: 20 May 2022; Published: 23 May 2022
KEYWORDS
Black-billed Cuckoo
call broadcast
Coccyzus americanus
Coccyzus americanus
Coccyzus erythropthalmus
Coccyzus erythropthalmus
detection probability
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