Elevational trends in butterfly phenology: implications for species responses to climate change

Abstract

1. Impacts of global change on the distribution, abundance, and phenology of species have been widely documented. In particular, recent climate change has led to widespread changes in animal and plant seasonality, leading to debate about its potential to cause phenological mismatches among interacting taxa. 2. In mountainous regions, populations of many species show pronounced phenological gradients over short geographic distances, presenting the opportunity to test for effects of climate on phenology, independent of variation in confounding factors such as photoperiod. 3. Here we show for 32 butterfly species sampled for five years over a 1700 m gradient (560–2260 m) in a Mediterranean mountain range that, on average, annual flight period is delayed with elevation by 15–22 days per kilometre. Species mainly occurring at low elevations in the region, and to some extent those flying earlier in the year, showed phenological delays of 23–36 days per kilometre, whereas the flight periods of species that occupy high elevations, or fly in late summer, were consistently more synchronised over the elevation gradient. 4. Elevational patterns in phenology appear to reflect a narrowing phenological window of opportunity for larval and adult butterfly activity of high elevation and late‐flying species. 5. Here, we speculate as to the causes of these patterns, and the consequences for our ability to predict species responses to climate change. Our results raise questions about the use of space–time substitutions in predicting phenological responses to climate change, since traits relating to flight period and environmental associations may influence the capacity of species to adapt to changing climates.

Studying plant–pollinator interactions in a changing climate: A review of approaches

“…Thus, it is not always possible to use an environmental gradient study to replace the lack of historical data (Illán et al, 2012). …”

Who flies first? – habitat‐specific phenological shifts of butterflies and orthopterans in the light of climate change: a case study from the south‐east Mediterranean

“…This is a widely used descriptor in butterfly studies, and considered to be more reliable than other descriptors such as the first day of adult appearance (Van Strien et al, 2008;Illán et al, 2012).…”

“…Phenology varies markedly over regional elevation gradients (e.g. Gordo et al, 2008;Illán et al, 2012) but also within an altitudinal belt or across different habitat types. Therefore, the use of habitat-specific variables (microclimatic such as temperature and humidity and environmental such as canopy cover and the availability of flower heads) could help us to better understand species' phenological response in the context of their surrounding environment.…”

Caterpillar biomass depends on temperature and precipitation, but does not affect bird reproduction

“…Long-time studies investigating the timing of plants' leaf phenology (Schaber and Badeck, 2005) and insects' (Van Asch et al, 2013) or birds' reproduction (Both et al, 2004) found markedly shifts into earlier season; but not all species seem to shift their phenology to the same extent (see review of Visser and Both, 2005). Shifts in timing also appear according to temperature changes along altitudinal gradients in plants' leaf phenology (Schieber et al, 2013), insects' activity patterns (Ill an et al, 2012) and birds' breeding behavior (Martin et al, 2009). Thus, these shifts lead to later seasons in colder, higher altitudes.…”