Long-term variation in the timing and height of annual peak abundance of caterpillars in tree canopies: Some effects on a breeding songbird
Climate warming affects trophic interactions in ecosystems, which has been documented for relationships between plants, herbivores and predators, including their relative densities, varying between taxons/guilds. In the case of leaf-eating caterpillars feeding in tree canopies the use of caterpillar...
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| Autores principales: | , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Elsevier
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/dd7fff0331ae47eeac45a11c8f1335c7 |
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| Sumario: | Climate warming affects trophic interactions in ecosystems, which has been documented for relationships between plants, herbivores and predators, including their relative densities, varying between taxons/guilds. In the case of leaf-eating caterpillars feeding in tree canopies the use of caterpillar frass fall as an indicator of density and production has proven to be advisable. Here we analysed annual variation in the peak mass of caterpillar frass fall and the timing of the occurrence of the peak mass in a deciduous forest site as compared with an urban park site during 16 consecutive years (2003–2018) in central Poland. Variation in the mean date of the frass fall peak mass among years was extensive, up to 20 days, with the sequence of the occurrence in the study habitats differing between years. There was a significant advance in the date of the peak frass fall in the course of the study years. There was also great variation in the peak frass fall mass between years and study sites. The tree canopy caterpillars were consistently less numerous in the urban park than in the deciduous forest. Cyclical outbreaks of caterpillars, whose signs were visible in the data set, possibly tended to decline. A decline in the annual peak mass of frass fall over the study period was found. No evidence for synchronization of the timing of blue tit Cyanistes caeruleus breeding with the timing of peak caterpillar abundance was found. The annual average peak mass of caterpillar frass fall proved to be a significant predictor of the annual mean number of fledgling blue tits per brood. Both the consistent pattern of spatio-temporal variation in the timing of peak availability and the abundance of tree-canopy caterpillars and the effects of caterpillar abundance on an insectivorous bird confirm that frass fall is a useful indicator of tri-trophic links to birds that prey upon caterpillars. |
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