Provide shady spots to protect butterflies from climate change

Date:
September 24, 2020
Source:
University of Cambridge
Summary:
Researchers have discovered significant variations in the ability
of different UK butterfly species to maintain a suitable body
temperature.

Species that rely most on finding a suitably shady location to keep
cool are at the greatest risk of population decline. The results
predict how climate change might impact butterfly communities,
and will inform conservation strategies to protect them.



FULL STORY ========================================================================== Researchers have discovered significant variations in the ability
of different UK butterfly species to maintain a suitable body
temperature. Species that rely most on finding a suitably shady location
to keep cool are at the greatest risk of population decline. The results predict how climate change might impact butterfly communities, and will
inform conservation strategies to protect them.


==========================================================================
The results, published today in the Journal of Animal Ecology, show
that larger and paler butterflies including the Large White (Pieris
brassicae) and Brimstone (Gonepteryx rhamni) are best able to buffer
themselves against environmental temperature swings. They angle their
large, reflective wings in relation to the sun, and use them to direct
the sun's heat either away from, or onto their bodies. These species
have either stable or growing populations.

More colourful larger species such as the Peacock (Aglais io) and Red
Admiral (Vanessa atalanta) have greater difficulty controlling their
body temperature, but even they are better than their smaller relatives
like the Small Heath (Coenonympha pamphilus).

The study found that some butterfly species rely on finding a spot at a specific temperature within a landscape -- termed a 'microclimate' -- to control their body temperature. Air temperatures vary on a fine scale: a
shaded patch of ground is cooler than one in full sun, for example. These 'thermal specialists', including Brown Argus (Aricia agestis) and Small
Copper (Lycaena phlaeas), have suffered larger population declines over
the last 40 years.

All butterflies are ectotherms: they can't generate their own body
heat. The populations of two thirds of UK butterfly species are
in decline: habitat loss and fragmentation, and more monotonous
landscapes have removed many of the microclimates butterflies need
to survive. Climate change is compounding the problem by causing more
extreme weather events and greater fluctuations in temperature.

Insects, including butterflies, pollinate around 85% of our food crops -
- providing a vital service worth billions of pounds globally. Protecting
a diverse range of species will provide long-term resilience: if numbers
of one species fall there are others to fill the gaps. Insects are also
an important food source for many other species, including birds.



========================================================================== "Butterfly species that aren't very good at controlling their temperature
with small behavioural changes, but rely on choosing a micro-habitat
at the right temperature, are likely to suffer the most from climate
change and habitat loss," said Dr Andrew Bladon, a Postdoctoral Research Associate in the University of Cambridge's Department of Zoology, and
first author of the report.

He added: "We need to make landscapes more diverse to help conserve many
of our butterfly species. Even within a garden lawn, patches of grass can
be left to grow longer -- these areas will provide cooler, shady places
for many species of butterfly. In nature reserves, some areas could be
grazed or cut and others left standing. We also need to protect features
that break up the monotony of farm landscapes, like hedgerows, ditches,
and patches of woodland." Landscapes with a diversity of heights and
features have a greater range of temperatures than flat, monotonous
ones. This applies on scales from kilometres to centimetres: from
hillsides to flower patches. Such structural diversity creates different microclimates that many butterflies use to regulate their temperature.

The research involved catching nearly 4,000 wild butterflies in
hand-held nets, and taking the temperature of each using a fine
probe. The surrounding air temperature was measured, and for butterflies
found perching on a plant, the air temperature at the perch was also
taken. This indicated the degree to which butterflies were seeking
out specific locations to control their body temperature. In total,
29 different butterfly species were recorded.

The study reveals that butterflies are either thermal generalists or
thermal specialists, and this does not always correspond with their
current categorisations as either habitat generalists or specialists.

"As we plan conservation measures to address the effects of climate
change, it will be important to understand not only the habitat
requirements of different butterfly species, but also their temperature requirements," said Dr Ed Turner in the University Museum of Zoology, Cambridge, who led the work.

He added: "With this new understanding of butterflies, we should be able
to better manage habitats and landscapes to protect them, and in doing so
we're probably also protecting other insects too." Over the past thirty
years, many species of butterfly have expanded their range northwards,
as more northerly places have become warmer due to climate change.

The ranges of species adapted to cooler environments are shrinking. These trends have been tracked for butterfly populations as a whole, but no
previous study has investigated how the individual butterflies that
make up these populations are able to respond to small scale temperature changes.

Bladon said: "I like to think of butterflies as the gateway drug. If we
can get people involved in butterfly conservation, that's the first step
to getting them to care about insects more broadly."

========================================================================== Story Source: Materials provided by University_of_Cambridge. The original
story is licensed under a Creative_Commons_License. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Andrew J. Bladon, Matthew Lewis, Eleanor K. Bladon, Sam J. Buckton,
Stuart Corbett, Steven R. Ewing, Matthew P. Hayes, Gwen
E. Hitchcock, Richard Knock, Colin Lucas, Adam McVeigh, Rosa
Mene'ndez, Jonah M.

Walker, Tom M. Fayle, Edgar C. Turner. How butterflies keep their
cool: Physical and ecological traits influence thermoregulatory
ability and population trends. Journal of Animal Ecology, 2020;
DOI: 10.1111/1365- 2656.13319 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200924082713.htm

--- up 4 weeks, 3 days, 6 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)