Cookies and email tracking

Cookies are text files containing small amounts of information which are downloaded to your device when you visit a website. Cookies are then sent back to the originating website on each subsequent visit, or to another website that recognises that cookie.

Cookies are useful because they allow a website to recognise a user’s device. issues cookies that are necessary for the provision of services to users and the smooth running of the website.

It can also issue optional cookies used for tracking how users interact with the website, in order to monitor performance and improve the service we provide to users.

Necessary cookies

  • Has_js - Indicate whether or not the browser has JavaScript enabled. Enables us to detect if content requiring JavaScript won’t function correctly

  • Cookie-agreed - Indicates user’s preference regarding the use of optional cookies

  • Aucp13n - Indicates whether to deliver cached content to the browser. Enables us to use caching to provide a more prompt service

  • SESSxxx - Indicates whether a user is logged-in to the BTO website. Allows us to give access to personalised or restricted content to logged-in users

  • JSESSIONID - Indicates whether a user is logged-in to a BTO survey application. Allows us to give access to data entry and survey management accounts

  • Some other temporary cookies may be used to facilitate specific functionality such as  viewing embedded Youtube videos and downloading data from our survey applications

Optional cookies

  • _ga / _gid / _gat - Google Analytics cookies. These cookies are used to collect information about how visitors use our website. We use the information to compile reports and to help us improve the website. The cookies collect information in an anonymous form, including the number of visitors to the website, where visitors have come to the website from, and the pages they visited. If you click on Google AdSense advert that brings you to the BTO website, that ‘conversion’ will be recorded anonymously. Read Google's overview of privacy and safeguarding data.

  • bto_campaign_extended / _medium / _appeal / _channel - BTO cookies to track the source of a website referral from BTO communications - on our social media accounts and in our print publications. These cookies are used to attribute a succesfully completed contribution on the website correctly, allowing us to judge the relative effectiveness of these different forms of communication.

  • _fpb - Facebook Pixel. Used to track conversions from our Facebook page and Facebook adverts we place that result in visits and activity on our website. The data reported to us by Facebook is anonymous. Facebook may associate these data with your Facebook account, and use them to tailor content and advertising to you, according to their terms of service.

How to manage cookies

While you can control the use of the optional cookies via our cookie opt-in banner, if you wish to suppress the use of required cookies you can do so by changing the settings in your browser. However, this may affect the performance of the BTO website in your browser, and some features may no longer work.

Find out how to manage cookies on popular browsers:

To opt out of being tracked by Google Analytics across all websites, visit

Email tracking

As a BTO member, Garden BirdWatcher, active surveyor or if you independently register to receive communications via email, email messages you receive may be trackable at an individual level. 

This allows us to determine how successful emails are - whether they have been opened and whether links have been clicked. This information is used to improve our email communications and may occasionally be used to send relevant further communications in response to your actions (e.g. clicking a particular link) or inactions (e.g. not opening an email) - in accordance with your contact preferences.

You can unsubscribe from email communications at any time using the unsubscription link contained in each message.

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