Songbirds incidentally ingest soil contaminated with lead and several species in the Southeast Missouri Lead Mining District have a negative relationship between soil lead concentration and reproduction. We used an individual-based model (IBM) to simulate nesting processes throughout the breeding season to estimate annual productivity for 5 songbirds in relation to soil-lead concentration. We modeled daily nest survival and number fledged in relation to soil lead and incorporated these relationships into the IBM using a Bayesian approach that fully captured parameter uncertainty and process variation. The proportion of the posterior distribution for the effect of soil lead on daily nest survival was mostly negative for Pipilo erythrophthalmus (Eastern Towhee), Passerina cyanea (Indigo Bunting), Cardinalis cardinalis (Northern Cardinal), Sialia sialis (Eastern Bluebird; f = 0.972, 0.990, 0.741, 0.581, respectively), and slightly positive for Spizella pusilla (Field Sparrow; f = 0.680). The proportion of the posterior distribution for the effect of soil lead on the number fledged from successful nests was mostly negative for S. pusilla, P. erythrophthalmus, and C. cardinalis (f = 0.867, 0.585, 0.508, respectively) and positive for P. cyanea and S. sialis (f = 0.773, 0.744). Simulated annual productivity decreased by 0.04–1.47 young/female/year among species across the range of soil lead concentrations, with the greatest declines for P. erythrophthalmus and P. cyanea. The probability of fledging one or more young changed from 51% to 15% for P. erythrophthalmus, 57% to 23% for P. cyanea, 60% to 48% for C. cardinalis, 94% to 84% for S. sialis, and 57% to 64% for S. pusilla as soil-lead concentration around a nest increased from 20 to 4,000 ppm. Most nest failures were the result of predation; therefore, we suggest lead may have affected birds' behavior at the nest, or affected nest site quality, which resulted in higher nest predation.
How to Cite
Thompson III, F. R., T. W. Bonnot, R. L. Brasso, M. C. Roach, K. Hixson, and D. E. Mosby (2024). Songbird annual productivity declines with increasing soil lead contamination around nests. Ornithological Applications 126:duae021.
LAY SUMMARY
Songbirds incidentally consume soil contaminated with lead while foraging near mining operations. Previous research in the Southeast Missouri Lead Mining District found a negative relationship between soil lead concentration and some songbird reproductive parameters, such as nest survival and number of young fledged.
We used data from this earlier study in an individual-based model to predict annual productivity by a female in a breeding season at increasing soil lead levels.
Annual productivity decreased by 0.04–1.47 offspring/female/year and the probability of fledging one or more young changed from 51% to 15% for Pipilo erythrophthalmus (Eastern Towhee), 57% to 23% for Passerina cyanea (Indigo Bunting), 60% to 48% for Cardinalis cardinalis (Northern Cardinal), 94% to 84% for Sialia sialis (Eastern Bluebird), and 57% to 64% for Spizella pusilla (Field Sparrow) as soil-lead concentrations increased.
Most nest failures were due to predation; therefore, we suggest possible explanations for the reduction in productivity are that lead affected birds' behavior and activity at the nest, or affected nest site quality, and resulted in higher nest predation.
Las aves canoras ingieren incidentalmente suelo contaminado con plomo y varias especies en el Distrito Minero de Plomo del sureste de Missouri tienen una relación negativa entre la concentración de plomo en el suelo y la reproducción. Utilizamos un modelo basado en individuos (MBI) para simular los procesos de anidación a lo largo de la temporada reproductiva para estimar la productividad anual de cinco aves canoras en relación con la concentración de plomo en el suelo. Modelamos la supervivencia diaria del nido y el número de volantones en relación con el plomo en el suelo e incorporamos estas relaciones en el MBI usando un enfoque bayesiano que capturó completamente la incertidumbre de los parámetros y la variación del proceso. La proporción de la distribución posterior para el efecto del plomo en el suelo sobre la supervivencia diaria del nido fue mayormente negativa para Pipilo erythrophthalmus, Passerina cyanea, Cardinalis cardinalis y Sialia sialis (f = 0.972, 0.990, 0.741, 0.581, respectivamente) y ligeramente positiva para Spizella pusilla (f = 0.680). La proporción de la distribución posterior para el efecto del plomo en el suelo sobre el número de volantones de nidos exitosos fue mayormente negativa para S. pusilla, P. erythrophthalmus y C. cardinalis (f = 0.867, 0.585, 0.508, respectivamente) y positiva para P. cyanea y S. sialis (f = 0.773, 0.744). La productividad anual simulada disminuyó en 0.04–1.47 jóvenes/hembra/año entre las especies a lo largo del rango de concentraciones de plomo en el suelo, con las mayores disminuciones para P. erythrophthalmus y P. cyanea. La probabilidad de emplumar uno o más jóvenes cambió del 51% al 15% para P. erythrophthalmus, del 57% al 23% para P. cyanea, del 60% al 48% para C. cardinalis, del 94% al 84% para S. sialis, y del 57% al 64% para S. pusilla a medida que la concentración de plomo en el suelo alrededor de un nido aumentó de 20 a 4000 ppm. La mayoría de los fracasos de los nidos fueron resultado de la depredación; por lo tanto, sugerimos que el plomo puede haber afectado el comportamiento de las aves en el nido, o afectado la calidad del sitio del nido, lo que resultó en una mayor depredación de los nidos.
