Scottish heatwaves are few and far between but erratic weather patterns caused by climate change are making them much more likely. This summer’s hot spell has tested all our gardens: can we and our fellow garden residents keep cool? Do we need to modify the garden to handle the heat?

Clearly, direct sun, air temperature, wind speed and heat radiation from the surrounding area determine how hot the garden feels. With the block paving in my yard I’m only able to stand the heat there for about 30 seconds just now while I can happily spend all afternoon in the dappled shade by the burn.

We must all find ways of escaping the searing sun and can resort to umbrellas, arbours or the cooling shelter of trees. And the garden will be much more bearable with less heat radiating from stone and concrete slabs.

Decking and plastic grass don’t help either; living green is best. Every garden plant, from flowers to shrubs and trees, helps reduce air temperature through evaporation, the process which releases tiny droplets of moisture into the atmosphere.

Heat tolerance is, of course, relative. Walking down Jedburgh High Street, I often hear moans of anguish when the mercury edges above 20℃, while my daughter-in-law from Greece reckons it’s only beginning to get hot above 30℃.

This adaptation to temperature applies to wildlife as well. Writing in the current British Trust for Ornithology’s newsletter, Susie Cunningham of Cape Town University says there’s evidence that increased temperature greatly increases chick mortality. Although some bird species can survive the searing heat of an African desert, others, like Bonxies or Great Skuas, that breed in Shetland, are becoming severely challenged. When it’s warmer than 14℃, they have to leave the nest to cool off in water. Other Bonxies may then attack and consume the nestlings.

Our garden birds are also impacted by higher temperatures and stay quietly in the shade offered by vegetation and trees. But then they are sheltering instead of foraging for vital food for themselves and their chicks. So they’ll need supplementary feed from us to be available early in the morning.

The body temperature of birds is around 40℃ and they struggle to survive when it’s hotter than this. During a heatwave, all is silent in the middle of the day while our avian friends work hard to keep cool. They fluff out their feathers so even a tiny breeze can cool them down. Interestingly, black feathers block out sunlight more effectively than white ones. Many species also half open their wings, wing drooping, and this exposes more body to any cooling air. They stand tall, with outstretched flanks and stretch out their ‘shoulders’ for better air circulation.

Birds also use evaporation from bare skin to cool down though they cannot sweat like us. Pigeons and doves increase the blood flow to tiny blood vessels near the skin surface, thereby altering the lipid content of the skin layer, which allows for increased evaporation.

Many of our resident garden birds, blackbirds, robins and chaffinches have to gape and pant to evaporate moisture from the moist lining of their mouths and throats. But this panting is hard work which in turn generates extra heat calling for more heavy panting.

To compensate for all this vital evaporation, we should provide water for the birds, both for them to drink and for bathing. But put it in a shaded spot, not out in the open as is recommended to help birds see predators like cats. The birds cannot afford to be in direct sun and the cats are probably in the shade too.

Plant of the week

Helenium ‘Coppelia’ haș gorgeous coppery red flowers with a large central “boss” of brown florets. It flowers through in to autumn and grows to about 90cm.