Fieldwork

Every year we monitor ospreys from their arrival in early spring to their departure for Africa in autumn.  We check all known nest sites in our area several times a season and, as well as ringing chicks, we collect data on breeding pairs, clutch sizes and numbers of chicks, to build up records on reproductive success. We endeavour to try to check as many adults as possible for colour rings so that we can identufy them as individuals. We use high spec Swarovski telescopes to carefully check ring details from a safe distance; gifted for our conservation work by Swarovski UK –  http://www.swarovskioptik.com 

Management of nests

Often, when ospreys are incubating their eggs or looking after young, a sudden storm will blow in and high winds will shake the nests.  Looking with binoculars, you can see the female battened down trying to stay in her nest and keep her eggs warm.  Sometimes, we have even seen nests being slowly dismantled by the wind and then it becomes obvious how important it is for ospreys to build their nest in secure trees.  We quickly realised that we could stabilise these nests, and became adept at tying in the main base of the nest to solid branches using wire or string.  We then discovered that we could anchor them much more effectively by cutting the top of the tree down to the first good fork and building a nest so that the following spring the ospreys can return and breed successfully.  This also led to us building nests on spec in new areas to encourage new pairs of birds.

Nests that have been in use for many years can also become overshadowed by the trees growing up around them, so we sometimes cut down surrounding trees to open up the view and make the nesting tree the most prominent one in the area, as preferred by ospreys.

 

 

 

 

 

 

 

 

To read more about our nest-building activities click on the relevant link on the left.

Checking nests

As part of our studies, we are keen to record the number of eggs in each nest in order to keep a check on the breeding success and productivity of each breeding pair.  We use a very long aluminium pole with a small mirror fitted on the end.  By using binoculars, we can look in the mirror to check the contents of most of the nests without unduly disturbing the birds.  The checks are carried out under licence from the governments and we take great care to make sure that the birds are not unnecessarily disturbed.  We do not, e.g., visit nests when it is raining or very windy or whilst a female is actually laying.

We visit each nest several further times per season to check how many chicks are present and to monitor their progress and whether or not they fledge successfully.  This data enables to build up profiles on lifetime reproductive success for each bird.

 

 

 

 

 

 

Ringing

In late June and July, we, and other osprey workers ring as many young ospreys as possible as part of the National Bird Ringing Programme run by the British Trust for Ornithology (BTO).  A metal ring inscribed with a unique number and the London address of the British Museum is placed around one leg of each chick.  The other leg is fitted with a plastic, coloured ring inscribed with numbers or letters.  Each unique colour ring allows us to track when a bird comes back to Scotland or to follow its progress on migration or in Africa.

Whilst ringing we also weigh each chick and take measurements of the wing and tail length and take note of unusual features such as missing feathers on the back of the neck from sibling aggression, or fault bars, distinctive weak marks across the feathers caused by a lack of food.

 

 

 

 

 

 

For further details on ringing or to report a ring number click on the relevant link on the left.