Tuesday 30 July 2019

Innovative use of a cavity liner

When one installs internal boxes, one should try to either make them unobtrusive or an attractive feature.

One of the first internal swift box projects we did in 2014 used a 30mm wide cavity liner which we cut into pieces and then reassembled into a half-brick entrance (see here).  Then in 2016 Barbara Wager installed internal boxes in a stone wall with a system of entrances cast in situ (see here).

Here, Barbara has combined these 2 ideas resulting in a practical solution that is simple, effective and attractive.

In her own words:

"The nest boxes were made by taking out facing stones, inserting the vent brick slices, mortaring in with tiles over the entrance and then vaselined formers were mortared in. Inside they are quite roomy and the walls mortared to prevent chicks wandering into the wall fabric – what a fate. Our builder agreed that the nests would not cause the house to fall down. The vent bricks made three slices each. They’ll be sheltered by the guttering. Each nest was provided with goose feathers, as ours are still moulting. We haven’t installed cameras nor do we expect to ever be able to get up there again. Over to the swifts. The speaker will be over a bedroom window so we should be able to reach it in case of failure."

Sunday 21 July 2019

Cameras in Swift boxes

Many people insert a camera into their Swift boxes. Normally the only option is to place the camera somewhere between the entrance and the nest, so at no time can you see the whole "stage". Usually the camera is aimed at the nest, and you may be lucky to see some wing tips as the birds peer out of the entrance.

This post is the result of attempts to get better pictures with cameras in nest boxes, particularly in All Saint's Church Landbeach.  It is part of a project to generate interest and awareness of swifts in churches sponsored by British Birds Charitable Trust.

We do 3 things:
  • Modify the nest box so that either the nest is between the camera and the entrance (or so that the entrance is between the camera and the nest)
  • Include white lights
  • Choose an appropriate focal length for the lens.

Nest box modification
In Landbeach church in 2018, 8 boxes were occupied (increased to 11 pairs this year, 2019). We modified 4 of these by extending them with a housing to take a camera. We installed 2 cameras, which are easy to move from one modified box to another. The original boxes had internal dimensions W 200, D 200, H 150 and were positioned behind louvres in the belfry.  The camera housing simply hangs onto the back of the box.

Original nest box with camera housing extension.
White lights
We used analogue cameras from Green Feathers who also supplied the white lights. These cameras are not as high quality as WIFI or IP cameras, but they are certainly easier to deploy. The lights have a sensor so that they are switched on and off suddenly when the sun comes up and goes down. When the lights are off, the camera works in the infrared, producing the familiar ghostly images at night.

Any concerns that the Swifts would be disturbed by sudden changes in light levels were unjustified - they appear to take no notice (similarly, they take no notice of some very loud bell-ringing).

The lights not only enable one to see colour,  they greatly improve the quality of the imagery and they greatly reduce light through the entrance dazzling the camera.

Lens focal length
One needs to choose a focal length compatible with the desired field of view. Too long a focal length will restrict it and too short will mean that things of interest appear too small. We used a focal length of 2.8mm

Example results

Video-clip from 4th July

Video-clip from 20th July

Video-clip from 27th July

Video clip from 26th July - a late returning adult (infrared lighting)

The north side of the belfry with 4 camera boxes on top