A Nearctic-Neotropical Migratory Songbird\u2019s Nesting Phenology and Clutch Size are Predictors of Accumulated Cyclone Energy

Christopher M Heckscher

doi:10.1038/s41598-018-28302-3

Christopher M Heckscher

Open Access

https://doi.org/10.1038/s41598-018-28302-3

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Abstract

The breeding season phenology of Nearctic-Neotropical migratory songbirds is constrained by subsequent seasons resulting in single-brooded behavior (one successful clutch per year) in some species. Early cessation of the nesting season prior to an active hurricane season will allow for behavioral plasticity during a physiologically challenging migration. Hurricane activity shows a high degree of inter-annual variability. I show that a single-brooded Nearctic-breeding species’ (Catharus fuscescens) nesting phenology and clutch size are significant predictors of Accumulated Cyclone Energy. The most skilled predictive model includes both mean clutch initiation date and mean clutch size (R2 = 0.84). Spearman rank correlation coefficients for both predictors with subsequent major hurricanes (1998–2016) are −0.55 and 0.52, respectively. Therefore, May and June clutch initiation and clutch size showed stronger correlations with subsequent hurricanes than early season (prior to August) meteorological predictions widely publicized by CSU, NOAA, and TSR (≤0.45, 2003–2014). Rainfall anomalies in the southern Amazon basin associated with ENSO cycles are a possible proximate cue affecting phenology and clutch size. This discovery potentially has far-reaching ornithological, meteorological, and social implications and shows that tropical storms significantly constrain breeding season behavior providing renewed evidence that hurricane activity is a primary factor regulating Nearctic-Neotropical migratory songbird populations.

Highlights

The breeding season phenology of Nearctic-Neotropical migratory songbirds is constrained by subsequent seasons resulting in single-brooded behavior in some species
Recognizing that reproductively unsuccessful female Veeries cease re-nesting attempts earlier in some years than others, and that reproductive phenology has a direct effect on the timing of migration[11,17], I tested the hypothesis that early cessation of the nesting season occurs in years with a propensity for high hurricane activity
If nesting phenology is significantly constrained by active hurricane seasons and clutch sizes are affected by environmental conditions preceding those seasons both should be predictors of hurricane activity

Summary

Accumulated Cyclone Energy

The breeding season phenology of Nearctic-Neotropical migratory songbirds is constrained by subsequent seasons resulting in single-brooded behavior (one successful clutch per year) in some species. Rainfall anomalies in the southern Amazon basin associated with ENSO cycles are a possible proximate cue affecting phenology and clutch size This discovery potentially has far-reaching ornithological, meteorological, and social implications and shows that tropical storms significantly constrain breeding season behavior providing renewed evidence that hurricane activity is a primary factor regulating Nearctic-Neotropical migratory songbird populations. Recognizing that reproductively unsuccessful female Veeries cease re-nesting attempts earlier in some years than others, and that reproductive phenology has a direct effect on the timing of migration[11,17], I tested the hypothesis that early cessation of the nesting season (i.e., molt initiation) occurs in years with a propensity for high hurricane activity. If nesting phenology is significantly constrained by active hurricane seasons and clutch sizes are affected by environmental conditions preceding those seasons both should be predictors of hurricane activity

Results and Discussion

Methods

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