Phenological research based on natural history collections: Practical guidelines and a lepidopteran case study

Abstract

Natural history collections (NHCs) have been indispensable to understanding longer‐term trends of the timing of seasonal events. Massive‐scale digitization of specimens promises to further enable phenological research, especially the ability to move towards a deeper understanding of drivers of change and how trait–environment interactions shape phenological sensitivity. Despite the promise of NHCs to answer fundamental phenology questions, the use of these data resources presents unique and often overlooked challenges requiring specialized workflow steps, such as assembling multisource data, accounting for date imprecision and making decisions about trade‐offs between data density and spatial resolution. We provide a set of key best practice recommendations and showcase these via a case study that utilizes NHC data to test hypotheses about spatiotemporal trends in adult Lepidoptera (i.e. butterflies and moths) flight timing across North America. Our case study is a worked example of these best practices, helping practitioners recognize and overcome potential pitfalls at each step, from data acquisition and cleaning, to delineating spatial units and proper estimation of phenological metrics and associated uncertainty, to building appropriate models. We confirm and extend the critical importance of voltinism and diapause strategy, but less‐so daily activity patterns, for predicting Lepidoptera phenology spatiotemporal trends. Our case study also showcases the unique power of NHC data to test existing hypotheses and generate new insights about temporal phenological trends. Specifically, migratory species and species that enter diapause as adults are advancing the start of flight periods in more recent years, even after accounting for climate context. These results highlight the physiological and adaptive differences between species with different overwintering strategies. We close by noting the value of partnerships between data scientists, museum experts and ecological modellers to fully harness the power of digital data resources to address pressing global change challenges. These partnerships can extend approaches for integrating multiple data types to fully unlock our understanding of the tempo, mode, drivers and outcomes of phenological changes at greater spatial, temporal and taxonomic scales. Read the free Plain Language Summary for this article on the Journal blog.

Weather anomalies more important than climate means in driving insect phenology

“…Recent work on plants (Li et al 31 ) and insects (Belitz et al 25 ) have shown that flowering and insect flight durations are longer in warmer areas in North America. Here we show that this general climate context matters less than unusual weather in determining many aspects of insect adult flight phenology.…”

“…Here we use carefully curated phenometric estimates for Lepidoptera (moths and butterflies) of the Eastern USA generated from natural history collections (NHC) data. Lepidoptera are well-suited for phenology studies 24 , 25 , given that they have been well collected for centuries 26 , and have temperature-dependent developmental rates 27 . Recent work has also elucidated how key Lepidopteran life-history traits mediate phenological responses, providing a framework for further examining the importance of anomalous weather events.…”

Climate, landscape, and life history jointly predict multidecadal community mosquito phenology

“…Assembling key trait data and Fitting Phenology Models: We focus on two key traits that may impact phenological responses: overwintering stage and early versus late ight timing 42 . These two traits have been used in other studies and both have been shown to strongly relate to phenological responsiveness to both climate and landscape 42,43 . We determined the overwintering stage for mosquito species using literature resources (see Table 1 in Results).…”

Leveraging natural history collections to understand the impacts of global change

“…the timing of biological events) in recent decades and centuries (Vitasse et al, 2022; Willis et al, 2017) in response to global change continues to accrue, and features in more than half a dozen papers in this Special Feature. Belitz et al (2023), in Functional Ecology , provide a framework and methodological checklist to address key questions in broad‐scale phenological patterns, using museum specimens on North American lepidopterans as a test case. Similarly, Dorian et al (2023) analysed 168 years of museum specimens and sighting data to assess phenological shifts for 70 species of solitary bees and found that, like many taxa, solitary bees have advanced their phenologies and lengthened their flight period.…”