Increasing levels of global environmental change may have negative impacts on fertility and embryo viability in animals that could explain a recently reported increase in hatching failure in bird eggs across the globe. Here we test this relationship again by analyzing a dataset containing almost twice as many species and covering a longer time period than earlier works (n = 431 species during the period 1906–2022). We also tested for effects of Red List status and global population size. We found that hatching failure rates in a combined group of bird species currently classified as threatened (IUCN Red List categories Critically Endangered, Endangered and Vulnerable) or Near Threatened, peaked in the late 1970s to early 1980s and thereafter declined. A similar trend also existed in species with relatively small global populations. In contrast, no temporal trends were found in species in the Least Concern category, or in species with large global populations. Moreover, hatching failure rates declined significantly with increasing global population sizes. The temporal peak of hatching failure rates in threatened and Near Threatened species corresponds with the peak in environmental levels of the insecticide DDT. While this could suggest that environmental pollution caused the temporal trends in hatching failure rates, effects of inbreeding in small and threatened populations sampled more frequently during this period could not be excluded. Although we found no evidence suggesting that the rates of hatching failure in bird eggs are increasing, the current study supports previous works showing that species of high conservation concern appear to be more susceptible to factors leading to reproductive failure than other species.
How to Cite
Heggøy, O., J. Gohli, and T. Lislevand (2024). Avian hatching failure rates did not increase during the last century, although species of high conservation concern appear particularly susceptible to factors leading to reproductive failure. Ornithological Applications 126:duae018.
LAY SUMMARY
Increasing global environmental change may negatively affect fertility and embryo viability in free-living animals, and this could potentially explain a recently reported increase in hatching failure rates of bird eggs in recent decades.
The temporal trend in hatching failure rates was here re-visited by analyzing a more comprehensive dataset than previous works, and also testing for effects of Red List status and global population size.
There was no evidence for a general increase in hatching failure rates in bird eggs during the last century.
Threatened and Near Threatened species, and species with small global populations, showed a temporary increase in hatching failure rates which peaked during the late 1970s to early 1980s.
Hatching failure rates decreased with global population size and generally increased with species' extinction risk.
Possible causes for the peak in hatching failure rates in small and/or declining bird populations could be varying levels of environmental pesticides like DDT, or inbreeding in small populations sampled more frequently during this period.
There was no evidence suggesting that the rates of hatching failure in bird eggs are currently increasing.Yet, the current study supports earlier findings that species of high conservation concern appear to be more susceptible to factors leading to reproductive failure than other birds.
Los niveles crecientes de cambio ambiental global pueden tener impactos negativos en la fertilidad y viabilidad embrionaria de los animales que podrían explicar el aumento recientemente reportado del fracaso en la eclosión de los huevos de las aves en todo el mundo. Aquí evaluamos esta relación nuevamente analizando un conjunto de datos que contiene casi el doble de especies y cubre un período de tiempo más largo que los trabajos anteriores (n = 431 especies durante el período 1906-2022). También evaluamos los efectos del estatus en la Lista Roja y el tamaño de la población global. Encontramos que las tasas de fracaso en la eclosión en un grupo combinado de especies de aves actualmente clasificadas como amenazadas (categorías de Lista Roja de la UICN: En Peligro Crítico, En Peligro y Vulnerable) o Casi Amenazadas, alcanzaron su punto máximo a fines de la década de 1970 hasta principios de la década de 1980 y luego disminuyeron. Una tendencia similar también existía en especies con poblaciones globales relativamente pequeñas. En contraste, no se encontraron tendencias temporales en especies en la categoría de Preocupación Menor, o en especies con grandes poblaciones globales. Además, las tasas de fracaso en la eclosión disminuyeron significativamente con el aumento de los tamaños poblacionales globales. El pico temporal de las tasas de fracaso en la eclosión en especies amenazadas y Casi Amenazadas se corresponde con el pico en los niveles ambientales del insecticida DDT. Si bien esto podría sugerir que la contaminación ambiental causó las tendencias temporales en las tasas de fracaso en la eclosión, los efectos de la endogamia en las poblaciones pequeñas y amenazadas muestreadas con más frecuencia durante este período no podrían excluirse. Aunque no encontramos evidencia que sugiera que las tasas de fracaso en la eclosión de los huevos de las aves están aumentando, el estudio actual respalda trabajos anteriores que muestran que las especies de alta preocupación para la conservación parecen ser más susceptibles que otras especies a los factores que conducen al fracaso reproductivo.
