Consequences of phenological shifts and a compressed breeding period in Magellanic penguins

Abstract

Phenological shifts may ameliorate negative effects of climate change or create carryover effects and mismatches that decrease fitness. Identifying how phenological shifts affect performance is critical for understanding how individuals and populations will respond to climate change, but requires long‐term, longitudinal data. Using 34 yr of data from the Magellanic penguin (Spheniscus magellanicus) colony at Punta Tombo, Argentina, we examined the consequences of the delayed onset of breeding (i.e., arrival and egg‐laying dates) that has occurred at the colony since 1983. To understand how the delay propagates through the rest of the reproductive cycle, we identified phenological trends in hatch and fledge dates. Median hatch dates were 0.29 d later each year, amounting to a 10‐d shift over the course of the study. Median fledge dates did not shift over the 34‐yr period, however, thus shortening the median nestling period duration by 14%. We tested several predictions regarding performance outcomes of the compressed nestling period, finding that later‐hatched chicks fledged significantly younger than earlier‐hatched chicks, and that younger fledglings left the colony with smaller bills and with more chick down. Interestingly, although younger chicks fledged significantly lighter and in worse body condition than older fledglings early in the study, this trend reversed over time, with younger chicks actually fledging heavier and in better body condition in more recent years. Smaller and lighter fledglings were less likely to recruit to the colony as adults. We find that delayed breeding has significantly compressed nestling periods at Punta Tombo, influencing chick growth and fledgling condition. These findings highlight the importance of studying phenology across multiple life events to understand the consequences of phenological shifts for organismal fitness.

Climate change and phenology

“…The average time until fledging advanced by 15.4 and 18.6 days for blue and great tits, respectively. Further south, Magellanic penguins ( Spheniscus magellanicus ) have shifted median hatch dates 10 days from 1983 to 2017 (Cappello & Boersma, 2021). Because median fledge dates did not shift over the 34 years, median nestling period decreased by 14%, impacting chick growth.…”

“…Shifts in phenology have the potential to offset negative effects of climate change, or they may create carryover effects and mismatches that decrease fitness (Cappello & Boersma, 2021). Quantifying such shifts is thus essential to understanding and predicting the consequences of climate change for ecological communities.…”

Long‐term patterns in ecosystem phenology near Palmer Station, Antarctica, from the perspective of the Adélie penguin

“…Future work should also consider the width of optimal windows, in addition to the timing of key events that were focused in this study, which could be more important as a narrow window may not be sufficient for processes like reproduction (Visser & Both, 2005). Further, it may be important to examine how phenological shifts propagate across an annual cycle where phenological compression or stretching can impact demographics (Cappello & Boersma, 2021). Studies rarely document phenological shifts in relation to food resource quality (Visser & Both, 2005), which is a near-term objective of our monitoring program.…”

“…We used 54 days after hatch to highlight fledge dates. In Adélie and other penguin species, CFM is an important indicator of chick overwinter survival and subsequent recruitment into the breeding population (Cappello & Boersma, 2021; Chapman et al, 2010). Protocols were carried out in accordance with the approved guidelines of the Columbia University Institutional Animal Care and Use Committee (Assurance number AAAH8959).…”

Climate drives anuran breeding phenology in a continental perspective as revealed by citizen‐collected data

“…Climate change therefore can have negative demographic effects, causing population decline or even species extinction (Cahill et al, 2013; Curtis et al, 2021). In many circumstances, the behavioural responses of the animals to the change can also decrease fitness, resulting in lower population recruitment as a result of a more restricted breeding period (Cappello & Boersma, 2021).…”