Angus towns are at the heart of a Tayside-wide mission to reverse declining swift numbers.
Populations of the “black boomerangs” – which return to their nests in Scotland at this time of year – have plummeted by 60% in recent years.
Environmentalist have started a project to measure populations and Tayside Biodiversity Partnership co-ordinator Catherine Lloyd said the birds were normally first spotted in Montrose.
“You would expect colleagues in Perthshire to see them first, but we think they swoop in from the east on the way back from Africa.
“The first sightings in Montrose will confirm what we think, or maybe blow it out the water, but it is important we find out where people see the first swifts.”
She said populations were falling due to homeowners and builders destroying nests as they renovate buildings between May and August.
She said: “The noise swifts make is the sound of summer but it is seriously under threat and we will lose them if we are not careful.”
She said the birds, which are often confused with swallows, like to nest in sandstone buildings and other older buildings ripe for renovation, such as Dundee tenements.
New planning applications will be checked against population data collected so experts can provide best advice to home owners and developers.
“Swifts are black boomerangs that fly around screaming with joy and we need to protect them,” she added.
Swifts are born in Scotland before flying to Africa in an 8,000 mile round trip. They do not land for the first three years of their lives but then nest.