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Total accumulated growing degree days (GDD) for (a) each of 17 years averaged across all sites and (b) each of 120 sites averaged across all years, ordered by latitude from south to north.
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Global climate change is causing shifts in phenology across multiple species. We use a geographically and temporally extensive data set of butterfly abundance across the state of Ohio to ask whether phenological change can be predicted from climatological data. Our focus is on growing degree days (GDD), a commonly used measure of thermal accumulati...
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... this study, we are able to distinguish the abilities of GDD and date to predict phenology in an unusually large data set on butterfly species abundance across 120 sites in Ohio for 17 years, where we observe high levels of both interannual and latitudinal variation in GDD (Fig. 1) and Sparks 2000, Forister and Shapiro 2003, Stefanescu et al. 2003). With these data, we asked whether GDD or date better predicted phenology in terms of first emergence and peak abundance for 13 common butterfly species across the state. We define predictability as the ability to predict date of emergence or date of peak abundance ...
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... accumulated annual GDD averaged among all sites ranged from 1271 (SD ¼ 127) to 1729 (SD ¼ 150; Fig. 1a). Total accumulated GDD averaged among all years at each site ranged from 1247 (SD ¼ 120) to 1899 (SD ¼ 147; Fig. ...
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... accumulated annual GDD averaged among all sites ranged from 1271 (SD ¼ 127) to 1729 (SD ¼ 150; Fig. 1a). Total accumulated GDD averaged among all years at each site ranged from 1247 (SD ¼ 120) to 1899 (SD ¼ 147; Fig. ...
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... outperformed date and more accurately predicted emergence in 13 of 14 species (Table 1, Fig. 2a). The difference between the numbers of site-year observations where GDD performed better compared to date was significant for M. cymela, C. eurytheme, P. tharos, S. cybele, C. pegala, P. troilus, and T. lineola (P 0.05) and marginally significant for A. numitor (0.05 , P 0.10 ). ...
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Citations
... Lepidopteran systems are well-poised to address questions regarding the prevalence and potential mechanisms of longitudinal range shift responses and the role of local climate velocity. This taxonomic group has a proclivity towards non-typical range shifts (longitudinal and downslope) (Lenoir et al., 2010), and is highly sensitive to changes in temperature and moisture (Cayton et al., 2015;Diamond et al., 2014;Hällfors et al., 2023;Hordley et al., 2023). ...
... Here, we take advantage of fine scale spatiotemporal monitoring of butterflies in the Midwestern United States (Ohio Lepidopteran Monitoring Program) representing 18-years of data across a spatial extent spanning over 116,000 km 2 to explore how and why butterfly species are shifting their ranges. Previous research using data from the Monitoring Program shows that butterfly abundance has declined over time for most species (Wepprich et al., 2019), and that phenology is changing depending on number of growing degree days (measure of thermal accumulation) (Cayton et al., 2015) and the cumulative impacts of urbanisation and increasing environmental temperature (Diamond et al., 2014). The next step in understanding how climate change is impacting butterfly species in the USA requires understanding how they are shifting their ranges. ...
Species are often expected to shift their distributions either poleward or upslope to evade warming climates and colonise new suitable climatic niches. However, from 18‐years of fixed transect monitoring data on 88 species of butterfly in the midwestern United States, we show that butterflies are shifting their centroids in all directions, except towards regions that are warming the fastest (southeast).
Butterflies shifted their centroids at a mean rate of 4.87 km year⁻¹. The rate of centroid shift was significantly associated with local climate change velocity (temperature by precipitation interaction), but not with mean climate change velocity throughout the species' ranges.
Species tended to shift their centroids at a faster rate towards regions that are warming at slower velocities but increasing in precipitation velocity.
Surprisingly, species' thermal niche breadth (range of climates butterflies experience throughout their distribution) and wingspan (often used as metric for dispersal capability) were not correlated with the rate at which species shifted their ranges.
We observed high phylogenetic signal in the direction species shifted their centroids. However, we found no phylogenetic signal in the rate species shifted their centroids, suggesting less conserved processes determine the rate of range shift than the direction species shift their ranges.
This research shows important signatures of multidirectional range shifts (latitudinal and longitudinal) and uniquely shows that local climate change velocities are more important in driving range shifts than the mean climate change velocity throughout a species' entire range.
... Both the Illinois Butterfly Monitoring Network and the Ohio Lepidopterists provide data throughout the period of study, while the Iowa Butterfly Survey Network and Michigan Butterfly Network provide data from the starts of their survey programs in 2007 and 2011, respectively. Subsets of these data have been previously analyzed to assess overall butterfly population trends in Ohio [6,58], and Monarch population trends in Illinois [25,59]. ...
Mounting evidence shows overall insect abundances are in decline globally. Habitat loss, climate change, and pesticides have all been implicated, but their relative effects have never been evaluated in a comprehensive large-scale study. We harmonized 17 years of land use, climate, multiple classes of pesticides, and butterfly survey data across 81 counties in five states in the US Midwest. We find community-wide declines in total butterfly abundance and species richness to be most strongly associated with insecticides in general, and for butterfly species richness the use of neonicotinoid-treated seeds in particular. This included the abundance of the migratory monarch (Danaus plexippus), whose decline is the focus of intensive debate and public concern. Insect declines cannot be understood without comprehensive data on all putative drivers, and the 2015 cessation of neonicotinoid data releases in the US will impede future research.
... Within a certain range of preferred temperature, the number of generations of pest species will upsurge, leading to more crop damage (Yamamura & Kiritani, 1998). Further, to predict the insect pest and plant phenology in agriculture growing degree days (GDD) model can also be followed where the daily total sum of degrees between a maximum and minimum temperature threshold is measured and annual heat accumulation is calculated (Cayton et al., 2015). ...
Extreme weather conditions accompanying the climate change potentially impact the global food production system including its pest profile scenario. Insect and nematode life strategies are largely governed by several climatic factors like temperature, precipitation, humidity, and atmospheric carbon dioxide level. Being the prominent environmental drivers of organismal biology, any fluctuation in these parameters affect the agriculturally important pest species as well. Temperature is one of the most pivotal environmental components, and global warming by rise in average temperature of the earth impacts the biogeographical range, distribution, abundance, survival, fitness, reproduction and growth rate of the agriculturally important insect and nematode pests. Further, changes in the macro- and micro-environment also affect the insect and nematode relied tritrophic interactions. However, the climate change driven consequences exert both positive and negative effects on these organisms. On a generalized account, a noticeable shift can be expected in the plant protection scenario in near future due to shifted pest problems. In this line, adequate monitoring of the pest population dynamics in relation to global climatic fluctuations will lead us to development of modeling based prediction tools and also help to modify the integrated pest management tactics to combat the disaster in a species and location specific manner.
... Spring and summer temperatures were summarized as accumulated growing-degree days (GDD), a commonly used metric of energy available for growth in ectotherms. For each hex cell and day, a daily GDD value was estimated using a single-sine approximation of daily temperature curves and generic thermal limits of (10°C, 33°C) (Abarca et al., 2024;Cayton et al., 2015). Accumulated GDD values were calculated by summing the daily GDD values with a hex cell, ...
Recent reports of insect declines have raised concerns about the potential for concomitant losses to ecosystem processes. However, understanding the causes and consequences of insect declines is challenging, especially given the data deficiencies for most species. Needed are approaches that can help quantify the magnitude and potential causes of declines at levels above species.
Here we present an analytical framework for assessing broad‐scale plant–insect phenologies and their relationship to community‐level insect abundance patterns. We intentionally apply a species‐neutral approach to analyse trends in phenology and abundance at the macroecological scale. Because both phenology and abundance are critical to ecosystem processes, we estimate aggregate metrics using the overwintering (diapause) stage, a key species trait regulating phenology and environmental sensitivities. This approach can be used across broad spatiotemporal scales and multiple taxa, including less well‐studied groups.
Using community (‘citizen’) science butterfly observations from multiple platforms across the Eastern USA, we show that the relationships between environmental drivers, phenology and abundance depend on the diapause stage. In particular, egg‐diapausing butterflies show marked changes in adult‐onset phenology in relation to plant phenology and are rapidly declining in abundance over a 20‐year span across the study region. Our results also demonstrate the negative consequences of warmer winters for the abundance of egg‐diapausing butterflies, irrespective of plant phenology.
In sum, the diapause stage strongly shapes both phenological sensitivities and developmental requirements across seasons, providing a basis for predicting the impacts of environmental change across trophic levels. Utilizing a framework that ties thermal performance across life stages in relation to climate and lower‐trophic‐level phenology provides a critical step towards predicting changes in ecosystem processes provided by butterflies and other herbivorous insects into the future.
Read the free Plain Language Summary for this article on the Journal blog.
... In turn, altered plant phenology feeds back on global ecosystems and influences fundamental processes such as the carbon and water cycle 1,5,6 , ecological interactions [7][8][9][10][11][12][13] , or land-atmosphere interactions 14,15 . Especially, temperate vegetation is sensitive to climate variability, since temperature is a core driver of phenological changes in these regions 16,17 . These co-dependencies highlight the crucial role of phenology and the vital importance to adequately document, monitor and model changes in the timing of phenological events on larger scales and at more fine-grained resolution. ...
Opportunistic plant records provide a rapidly growing source of spatiotemporal plant observation data. Here, we used such data to explore the question whether they can be used to detect changes in species phenologies. Examining 19 herbaceous and one woody plant species in two consecutive years across Europe, we observed significant shifts in their flowering phenology, being more pronounced for spring-flowering species (6-17 days) compared to summer-flowering species (1-6 days). Moreover, we show that these data are suitable to model large-scale relationships such as “Hopkins’ bioclimatic law” which quantifies the phenological delay with increasing elevation, latitude, and longitude. Here, we observe spatial shifts, ranging from –5 to 50 days per 1000 m elevation to latitudinal shifts ranging from –1 to 4 days per degree northwards, and longitudinal shifts ranging from –1 to 1 day per degree eastwards, depending on the species. Our findings show that the increasing volume of purely opportunistic plant observation data already provides reliable phenological information, and therewith can be used to support global, high-resolution phenology monitoring in the face of ongoing climate change.
... GDD, a cumulative calculation of temperature above a certain threshold (Gordon and Bootsma 1993), was used to quantify the amount of heat experienced during butterfly development during the spring of the year that specimens were collected as well as during the preceding summer when they were larvae. This approach for tracking heat available to heterothermic animals has been widely adopted to model or analyze development rate (Saunders et al. 2016, Kingsolver and Buckley 2020, Zylstra et al. 2022) and Cayton et al. (2015) showed that GDD was a better way to track the effects of warming on butterfly phenology than any other way of quantifying heat. The main drawback using GDD is that it does not account for the retarding effects of very high temperatures on growth rate, but in our study region, such warm temperatures did not occur. ...
Climate warming can cause arthropods to express plastic and/or evolved changes in morphology. Previous studies have demonstrated that body sizes of Arctic butterflies are influenced by the temperatures experienced as larvae. To investigate whether this was occurring among Alaskan butterflies, we analyzed temporal trends in the wing sizes of three Holarctic species, Colias hecla, Boloria chariclea and Boloria freija, using museum specimens collected in Arctic tundra regions of Alaska between 1971 and 1995. Wing length was compared to accumulated growing degree days (GDD) during both the spring of the year collected and the previous year's summer during the normal period of larval development. We used mixed‐effects models to test if spring and summer temperatures affected adult morphology. Results show that for every 1°C increase in average seasonal temperature, wingspans decreased between 0.7 and 5 mm, with B. freija the most strongly affected. Our results suggest that the morphological sensitivity of Arctic butterflies to warming is the outcome of interactions between life‐history traits and regional climate, with all species sensitive to warming the summer before the flight year as well as warming the spring of the flight year. Boloria freija, which overwinters as late instar larvae that do not feed before pupation the following spring, was particularly strongly affected by summer warming.
... Within a region, interannual comparisons of degree days indicate rates of warming in physiological time, while cross-regional comparisons of degree days, such as comparison of annual degree days along the latitudinal range of the blue crab, may aid predictions of future spawning season duration. Lastly, degree days have been used in studies on blue crab growth (Brylawski and Miller, 2006), reproduction (Darnell et al., 2009), survival (Glandon et al., 2019), and catch (Weiss and Downs, 2020) and can reliably predict phenology (Cayton et al., 2015). ...
Global temperatures are rising across marine ecosystems in response to climate change. Marine and estuarine-dependent species including the blue crab, Callinectes sapidus, may adapt to warming temperatures phenologically, by shifting the seasonal timing of biological events, such as reproduction. In Chesapeake Bay, average water temperatures have risen by an average 0.02°C per year since the 1980s. Extension of the blue crab spawning season, through earlier onset and later conclusion, may augment annual brood production and alter the efficacy of management strategies. The duration of the potential spawning season from 1985 to 2019 was assessed using degree days, and the observed spawning season from 1995 to 2019 was assessed using the occurrence of ovigerous crabs from the Virginia Institute of Marine Science Trawl Survey in the James River and in the mainstem of lower Chesapeake Bay. Spawning degree days (SDD) and reproductive degree days (RDD) were defined using minimum temperatures of 19°C and 12°C, respectively. The mean duration of the potential spawning season increased by 25% in SDD and 10% in RDD between 1985 and 2019 in the James River and lower Chesapeake Bay, respectively. This progressive expansion of the potential spawning season was not, however, reflected in the observed spawning season. Rather, the onset, conclusion, and duration of the observed spawning season were variable over the time series. The observed month of onset was driven by RDD in spring, whereby spawning began earlier during warmer springs. The spawning conclusion date was driven by the onset of spawning, rather than Fall temperature, such that the duration of the observed spawning season and, therefore, annual brood production did not change over time. In Chesapeake Bay, the spawning stock is protected by a sanctuary that is closed to fishing from mid-May to mid-September during the putative spawning season. An earlier start to the spawning season during warmer springs, as seen in recent years, is expected to reduce the efficacy of the spawning sanctuary and intensify exploitation of the spawning stock, without enhancing brood production, thereby reducing reproductive output of the blue crab population in Chesapeake Bay.
... Temperature changes and plant growth in spring drive emergence of herbivorous caterpillars and other arthropods (Cayton et al., 2015;van Asch & Visser, 2007), which in turn serve as fuel for insectivorous songbirds during their northward migrations (Graber & Graber, 1983;Strode, 2015;Wood & Pidgeon, 2015). Thus, increasing primary productivity serves as a proxy for food availability for insectivorous songbirds (Pettorelli et al., 2011), which can adjust their migration timing depending on spring temperature or vegetation phenology en route (Thorup et al., 2017;Tøttrup et al., 2008Tøttrup et al., , 2010Youngflesh et al., 2021). ...
... Unlike herbivorous waterfowl that synchronize their migration timing to track vegetation emergence in early spring (Figure 1, surfingleading edge), we predicted that the ground-foraging insectivores in our study would instead migrate behind the leading edge of the green wave of spring onset (Figure 1, surfing-trailing), tracking later stages of leaf development that correspond to increased arthropod prey (Cayton et al., 2015;Mayor et al., 2017;van Asch & Visser, 2007). ...
In temperate regions, the annual pattern of spring onset can be envisioned as a ‘green wave’ of emerging vegetation that moves across continents from low to high latitudes, signifying increasing food availability for consumers.
Many herbivorous migrants ‘surf’ such resource waves, timing their movements to exploit peak vegetation resources in early spring. Although less well studied at the individual level, secondary consumers such as insectivorous songbirds can track vegetation phenology during migration as well.
We hypothesized that four species of ground‐foraging songbirds in eastern North America—two warblers and two thrushes—time their spring migrations to coincide with later phases of vegetation phenology, corresponding to increased arthropod prey, and predicted they would match their migration rate to the green wave but trail behind it rather than surfing its leading edge.
We further hypothesized that the rate at which spring onset progresses across the continent influences bird migration rates, such that individuals adjust migration timing within North America to phenological conditions they experience en route.
To test our hypotheses, we used a continent‐wide automated radio telemetry network to track individual songbirds on spring migration between the U.S. Gulf Coast region and northern locations closer to their breeding grounds.
We measured vegetation phenology using two metrics of spring onset, the spring index first leaf date and the normalized difference vegetation index (NDVI), then calculated the rate and timing of spring onset relative to bird detections.
All individuals arrived in the southeastern United States well after local spring onset. Counter to our expectations, we found that songbirds exhibited a ‘catching up’ pattern: Individuals migrated faster than the green wave of spring onset, effectively closing in on the start of spring as they approached breeding areas.
While surfing of resource waves is a well‐documented migration strategy for herbivorous waterfowl and ungulates, individual songbirds in our study migrated faster than the green wave and increasingly caught up to its leading edge en route.
Consequently, songbirds experience a range of vegetation phenophases while migrating through North America, suggesting flexibility in their capacity to exploit variable resources in spring.
... Prediction 2: Warming will cause earlier egg hatching, possibly cued by a more rapid accumulation of degree-days. Developmental changes lead to changes in insect phenology (Cayton et al. 2015), and growing degree-days (GDD) provide a metric linking climatic conditions and insect phenology (Nufio et al. 2010). Changes in diurnal temperature ranges can substantially change degree-day accumulation and alter insect life history (Chen et al. 2015;Patterson et al. 2020). ...
... Extra generations arising from the warming treatments, beyond the two nominal generations per year, may produce larvae after the host plant senesces or dies for the year, increasing larval mortality. With high mortality in the final generation, the number of offspring that hatch the following season would subsequently decrease (Cayton et al. 2015). These trends have been documented in other Lepidoptera (Huey and Kingsolver 1993;Kingsolver and Huey 2008;Diamond et al. 2014;Miller-Rushing et al. 2010). ...
The Karner blue butterfly (Lycaeides melissa samuelis) (hereafter Karner blue) is a federally listed endangered species occurring in disjunct locations within the Midwest and Eastern United States. As a hostplant specialist and an ectotherm, the Karner blue is likely to be susceptible to effects of climate change. We undertook warming experiments to explore the temperature sensitivity of various Karner blue life history stages and traits. Over a two-year period, we exposed all Karner blue life stages to temperature increases of + 2, + 4, and + 6 °C above 1952–1999 mean temperatures. We analyzed the effect of these treatments on life history parameters likely related to fitness and population size, including development time, voltinism, degree-day accumulation, body weight, and morphology. Warming treatments resulted in earlier emergence and accelerated development, leading to additional generations. Warming also increased the number of degree-days accumulated during pre-adult development (i.e., egg hatch to eclosion). Results suggest that Karner blues developed in fewer days, in part, by putting on less mass as temperatures increased. As treatment temperature increased, adult body mass, length, and area decreased and voltinism increased. Females with lower adult mass and smaller body size produced fewer eggs. These results suggest a trade-off between accelerated development and decreased body size with decrease in adult mass and abdominal area being associated with reduced fecundity.
Implications for insect conservation
Changes in development timing and in voltinism can negatively affect phenological matching between the Karner blue and its obligate host plant, Wild lupine (Lupinus perennis), resulting in population decrease. Poorer phenological matching between insect and hostplant can occur across multiple generations, for example, negatively affecting overwintering population size. With increasing temperatures, smaller females will produce fewer eggs, which can also lead to poorer population outcomes across generations.
... If spring emergence in temperate reptiles is prompted by specific environmental cues such as temperature, we should expect emergence phenologies to be predictable using local climatic data. Wide-ranging species subject to latitudinal and elevational clines might exhibit phenological plasticity, similar to what is observed for insects (Cayton et al., 2015;Herms, 2004;Uelmen Jr et al., 2016), plants (Aslam et al., 2017) and mammals (Boutin & Lane, 2014). However, local adaptation or study methods have often confounded the identification of such spatial patterns (Andrews & Waldron, 2017;Blouin-Demers, Prior & Weatherhead, 2000). ...
... Due to the prevalence and apparent importance of temperature as a cue for emergence within the literature, we focused primarily on temperature-derived variables found to be important drivers of surface presence for C. horridus and other temperate reptiles, including maximum, minimum, and mean daily temperatures, five-day rolling minimum and maximum daily temperature, day of year, latitude, and accumulated degree days of base 5 • C (ADD). Accumulated degree days is a phenological measure of seasonally increasing cumulative mean daily temperature above a selected threshold and is frequently used to predict phenological events and organismal developmental stages for a variety of taxa (Boutin & Lane, 2014;Cayton et al., 2015;Herms, 2004;Uelmen Jr et al., 2016;Hoffman, 2021). We calculated Table 1 Environmental variables used to construct 32 candidate models predicting the daily surface presence of Timber Rattlesnakes (Crotalus horridus) during spring emergence at two sites in Illinois. ...
... Accumulated degree days allowed our model to capture the general increase in temperature occurring at refugia throughout the late winter and early spring. Accumulated degree days have a long history in phenological predictions of plants (Boutin & Lane, 2014), invertebrates (Cayton et al., 2015;Herms, 2004;Uelmen Jr et al., 2016), and to a lesser extent, reptiles (Hoffman, 2021;Turner & Maclean, 2022). Unlike other timerelated variables such as ordinal date and photoperiod (Martin, 1992), ADD allows for flexible predictions of daily surface presence by accounting for temperature variation across spatial (latitude and elevation) and temporal (years) extents. ...
Many temperate reptiles survive winter by using subterranean refugia until external conditions become suitable for activity. Determining when to emerge from refugia relies on the ability to interpret when above-ground environmental conditions are survivable. If temperate reptiles rely on specific environmental cues such as temperature to initiate emergence, we should expect emergence phenologies to be predictable using local climatic data. However, specific predictors of emergence for many temperate reptiles, including the Timber Rattlesnake (Crotalus horridus), remain unclear, limiting our understanding of their overwintering phenology and restricting effective conservation and management. Our objectives were to identify environmental cues of spring emergence for C. horridus in Illinois to determine the species’ emergence phenology, and to examine the applicability of identified cues in predicting emergence phenology across the species’ range. We used wildlife cameras and weather station-derived environmental data to observe and predict the daily surface presence of C. horridus throughout the late winter and early spring at communal refugia in west- central and northern Illinois. The most parsimonious model for predicting surface presence included the additive effects of maximum daily temperature, accumulated degree days, and latitude. With a notable exception in the southeastern U.S., the model accurately predicted the average emergence day for eight other populations range wide, emphasizing the importance of temperature in influencing the phenological plasticity observed across the species’ range. The apparent broad applicability of the model to other populations suggests it can be a valuable tool in predicting spring emergence phenology. Our results provide a foundation for further ecological enquiries and improved management and conservation strategies.
