Sitting at the top of the food chain, population numbers of grey herons (ardea cinerea) depend on their being able to find enough food – largely fish, frogs and small mammals. They can be negatively affected by poor water quality.
The distinctive birds are the second largest in the UK, after only mute swans, and can be seen all over the country.
Dr Mark Robinson, ecologist at the Canal & River Trust, said: “Herons are one of the most majestic sights on our waterways, and they're also a sign that all is well with the ecosystems they rely on. While we're constantly monitoring our water quality, with people's help we can get another insight into the health of wildlife around the waterways.
“As adult birds face no natural predators, they're the kings of the canals, and take their pick of fish, amphibians and small mammals around the waterways, even gobbling up the odd duckling. Large numbers of herons usually mean healthy, thriving canals and rivers, as they're natural barometers of water quality, fish stocks and much more – even down to the insect and invertebrate populations that feed their prey. Equally, if there are areas without many sightings, we can have a look into if there are any reasons they might be being put off.
“Whenever you spot a heron it's a real stop and stare moment, and is one of the experiences that make spending time on our waterways so special. By reporting your sighting through the Great Nature Watch app, you can also help us make sure they're drawn back to our canals and rivers for many years to come.”
There are believed to be around 13,000 breeding pairs of herons in the UK, nesting in large communal groups known as ‘heronries'. There's believed to be a long term trend of gradually increasing numbers of herons in the country, and although populations can still be adversely affected by harsh winters, widespread improvements in water quality and reduced levels of persecution are supporting the species' growth.
Sightings can be submitted by downloading our free mobile app, eNatureWatch (or search Canal & River Trust in the Apple App Store /Google Play Store). Anyone can take part and record as many sightings as they like between now and the end of September.