Tawny Owls are our most frequently encountered owl in and around gardens, but despite our familiarity with these birds, we know little about the impacts of urbanisation on their behaviour, and how it influences our ability to detect their presence.
The survey aimed to explore the impact of artificial light pollution and other aspects of urbanisation as well as environmental conditions on the likelihood of hearing Tawny Owls and seasonal changes in Tawny Owl calling behaviour.
Tawny Owl Calling Survey volunteers listened for the owls' familiar 'hooting' and 'kee-wick' calls in 2018 and 2019. Over 9000 volunteers submitted data: thank you to all who participated and made this survey a success.
About Tawny Owl calls
Tawny Owls are reliant on vocalisations, using them to show ownership of a breeding territory, as well as attracting a mate and reinforcing a pair bond.
Tawny Owls can make a variety of calls but the most familiar are their "kee-wick" and "hoot" sounds. The hooting or “twoo” sound is usually made by the male and is a territorial call. You can sometimes hear a female responding to a male’s “twoo” call with a sharp “kee-wick”. Together this duet produces the classic “twit twoo” sound, which many people associate with these owls.
What was involved?
The survey was easy to take part in - requiring a listen for 20 minutes during at least one evening between the 30th of September 2018 and the 31st of March 2019. Participants listened from their garden, local park or woodland - even whilst lying in bed with the window open! All information was valuable, so even zero counts were helpful.
Volunteers listened for their familiar 'hooting' and 'kee-wick' calls between sunset and midnight. All we asked was for people to tell us the date, start time of the 20-minute survey period, an estimate of cloud cover and importantly whether or not an owl was heard. If volunteers heard a Tawny Owl at another time of the week outside the survey period this could also be recorded.
Building on previous surveys
A previous survey also took place during 2005/06. We wanted to compare the results of this previous survey with the new data, to explore any changes.
The data from the previous survey were collected by 3,465 volunteers in 2005/06, who listened for Tawny Owls in their gardens. It helped us to learn factors which affect calling behaviour. We know that the time of day, the moon cycle, weather and distance to woodland impact the chances of hearing a Tawny Owl.
We wanted to take this a step further and explore the impact of artificial light pollution and other aspects of urbanisation on the likelihood of hearing Tawny Owls. At the same time, we also investigated seasonal changes in Tawny Owl calling behaviour more generally and explored whether urbanisation plays a role in this too.