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Abstract

For organisms living in seasonal environments, timing of breeding is key to ensuring reproductive success. Accordingly, temperate and polar seabird species follow seasonal pulses, matching their breeding events with peaks in ocean productivity. However, the seasonality of breeding has been much less explored in tropical seabirds. Here, we report seasonal variation in oceanography that affects reproductive success of the Brown Booby Sula leucogaster, a species widely distributed in the tropics. We monitored 61 nests during the 2019 breeding season at Bona Island, Gulf of Panama, and collected remote-sensing information for upwelling, sea-surface temperature, rainfall, chlorophyll-α concentration, wind speed, and wind direction. We used egg/chick survival probability and a sliding-window statistical approach to assess temporal changes in reproductive success. Maximum chlorophyll-α concentrations (linear and quadratic expressions) had the strongest influence over survival probability in the two to three weeks prior to the death of the egg/chick. After model averaging, we found that survival probability was positively correlated with maximum chlorophyll-α (confidence interval CI(β) = 0.19 to 2.54 mg/m3) and negatively correlated with (maximum chlorophyll-α)2 (CI(β) = −4.19 to −0.31 mg/m3). In addition, survival probability decreased with later laying dates (CI(β) = 0.43 to 1.74 days), indicating that chicks born earlier in the breeding season had higher chances of survival. Given the correlation between chlorophyll-α and upwelling, we concluded that Brown Booby reproductive success in the Gulf of Panama is influenced by upwelling and that breeding in this tropical species follows seasonal pulses like those observed in polar and temperate species.

DOI

http://doi.org/10.5038/2074-1235.50.2.1477

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50_2_119-124_Appendix.pdf (257 kB)
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