Saturday 17 August 2013

Nest Recording of Swifts in Boxes with Cameras

The increasing number of people with cameras in Swift nest boxes provides a great opportunity to obtain high quality nest records for the BTO. This could help to reverse the decline in numbers of Nest Record Cards for Swift in recent years

Written by Jake & Dick

The BTO's Nest Record Scheme provides important information about changes in populations over time, based on such factors as average egg laying date, clutch size, incubation and fledging period, and hatching and fledging success rates.

Nest record cards for Swift recorded each year
showing the recent decline (click graph to enlarge)
3 chicks with large primary feathers
(can you spot the 3rd one?)
We know there is an ongoing decline in the population of Swifts in this country, so it is important to collect data on breeding success rates, but no more than a hundred nest records are received each year, and this number has halved since 2010.

Historic data would be extremely valuable in helping to combat the dearth of records in recent years.

Moreover, the information on the cards is generally minimal, possibly no more than the record from a single visit.

Even with multiple visits, The BTO has to make intelligent inferences to determine egg laying, hatching and fledging dates. With cameras in boxes, there is the potential to determine the timing precisely of all of these events without any guesswork.

Example nest record card
Nest recording is not an arduous task, though the more you record, the better. The optimum would be to produce a series of up to 10 dated observations detailing the first sighting of an egg in the nest, the maximum clutch size and when it was first observed, the date of first hatching, the number of chicks present at approximately weekly intervals, together with their stage of development, and the timing of any failures or successful fledging.

In the (real) example shown here, we knew everything from the date the parents arrived, when the eggs were laid, when the eggs hatched, when the chicks fledged, and finally when the parent left for Africa. In this case, one parent went missing on 4th July. [The parent that survived carried a geolocator to Africa in 2011 and has returned since then.]

Note that although the instructions say that further visits should be included on continuation cards, the BTO nest record software cannot deal with more than 10 visits, meaning that all of the most essential information should be squeezed onto the first card.

In this example, we have inserted the last time there were 2 eggs, just before there was 1 chick This helps the BTO's algorithms to pin down the hatching date exactly. Because of the 10 visit restriction, we have not recorded the dates that the parents arrived on the card.

If you know that you will be unable to watch the camera for a period, record the last state of play, including nest contents, primary feather length etc. as well as the position on your return. See this pdf link, also referenced below, for how to describe chicks.

Anyone who would like to contribute can get in touch with the BTO at to register as a nest recorder and receive the necessary instructions and blank cards. It is essential that the data is submitted on these cards, as the BTO cannot handle any other format.
[ we understand that there will eventually be a web-based system]

If you already have such information recorded from previous seasons, it is an easy matter to transfer it to Nest Record Cards using the standard BTO codings.

For a fuller description of how to record Swift nest records download this pdf, written by Vince Lea.

We thank Dave Leech, BTO Senior Research Ecologist NRS, CES & RAS, for suggested improvements to this post.

BTO url:

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