Water Availability Coincides with Population Declines for an Endangered Butterfly

Abstract

Abstract:As global climate change causes population declines across numerous taxa, it becomes critical to understand the specific pathway by which climatic and anthropogenic factors influence population size. Water availability is a key environmental condition that links climate and humans to species response, especially for rare or threatened butterflies that are highly sensitive to changes in climate and the surrounding landscape. We use the wetland-dependent endangered St. Francis' satyr butterfly (Neonympha mitchellii francisci) to test how changes in water availability affect population size via changes in host plant growth. We show that long-term declines in water availability are directly linked to a decline in host plant growth and contributed to a population decrease of 95% for St. Francis' satyrs in the past decade, threatening the persistence of the species. Recent restoration work, which includes efforts to increase water availability via hardwood removal, has been successful in increasing population numbers. Many butterflies are broadly dependent on water availability and flow, and only by understanding the specific pathway that directly links water availability to species response can we make effective conservation plans to prepare for the altered water conditions of the future.

Higher Maximum Temperature Increases the Frequency of Water Drinking in Mountain Gorillas (Gorilla beringei beringei)

“…Undoubtedly, the direct impact of climate change is likely to be a bigger problem for species living in more arid environments that face reduced access to sufficient quantities of either free-standing sources of water or preformed water (Fuller et al, 2016;Cayton and Haddad, 2018;Mitchell et al, 2018;Wessling et al, 2018;Riddell et al, 2019;Young et al, 2019;Campos et al, 2020). Many avenues of future research into this topic remain to better determine how much of a risk increased temperature poses for the mountain gorillas.…”

“…Decreased water availability has been shown to drive increased mortality rates in several species (Cayton and Haddad, 2018;Riddell et al, 2019;Young et al, 2019;Campos et al, 2020). In contrast, rainforest dwelling species may obtain most or all of their water requirements from their diet (Karasov and del Rio, 2020).…”

Restoration success varies based on time since restoration in a disturbance‐dependent ephemeral wetland ecosystem

“…Host plants for the St. Francis' satyr include bunch‐forming sedges in the Carex genus, particularly C. mitchelliana and C. atlantica , which require saturated soils and a relatively open canopy with limited hardwoods present (Kuefler et al 2008). The extirpation of most beavers from the region by humans a century ago, along with the suppression of fire and increased human activity in the form of agriculture, development, roads, and foot traffic, has led to a limited number of connected streams that support St. Francis' satyr populations (Cayton & Haddad 2018). Currently the amount of available St. Francis' satyr habitat is thought to comprise less than 10 ha across a limited number of wetland sites, supporting an overall St. Francis' satyr population size in the low thousands (Cayton et al 2015).…”