Nest Building

Nest building has been integral to the recovery of the osprey across Scotland and other parts of the world.  Of course, ospreys can build their own nests, but while they are rare, and still missing from much of their ancestral range, active management is beneficial to the species. The aim is to increase the breeding population of ospreys in the British Isles and to restore it to its previous range where practical, as a larger geographical spread of the species will enhance the osprey’s long-term chances of survival.

One problem is that ospreys have a very slow ability to recover lost range throughout the world. This was most noticeable in North America where recovery from the pesticide crash of the 1950s/1960s was very slow. Conservationists overcame this by translocating and hacking young and by building artificial nests.  In Scotland the recovery has also been very slow, with an average natural spread of about four km per year. (Although this has changed in recent years following the translocation project at Rutland Water in central England.)

This slow recovery is due to various factors.  Ospreys prefer to breed near other ospreys as they are semi-colonial and fish at common feeding sites.  Young adult ospreys prefer to take over an established eyrie in a colony or build nearby, rather than build a new eyrie in a new locality.  Ideally they prefer to find an experienced breeding bird with an established nest which has lost its previous year’s mate.  Ospreys can waste valuable time early in the season attempting to rebuild damaged nests, especially when a main supporting branch has broken.  This can result in nesting failures and even to the break up of pairs.

There are therefore a number of instances in which we choose to build nests:

  • To enhance breeding success of established pairs by rebuilding eyries damaged by winter gales or which are insecure. To maximise the production of young while the population is depleted.
  • To move pairs from robbed or disturbed nests to a new nest in a secure area.
  • To provide secure eyries for young pairs which arrive late and may not build a nest in time to lay eggs. This encourages young birds to breed successfully at three years of age and can increase life-time reproduction. First time breeders are the most likely to lose nests in summer storms.
  • To encourage ospreys to spread out from the nucleus of a colony.
  • To encourage ospreys to join a breeding pair in a new area and thus create a new colony.
  • To encourage ospreys to breed in new regions.
  • To provide nest sites in areas with few suitable natural trees, especially in large areas of new afforestation where ospreys are clearly restricted by lack of nest sites, or in treeless wetlands.

Pairs breeding in built or rebuilt nests have been shown to be more successful than natural nests. This is particularly the case with first time breeding pairs building their own nest.  It is important to bear in mind that in ancient times before human persecution most young ospreys would have bred in long-established and secure eyries. In the British Isles, artificial nest-building is enabling us to regain the suite of established eyries much faster than would naturally occur.

Nests need to be securely built and lined with suitable nesting material

Ospreys using an artificially constructed nest

 

 

 

 

 

 

 

Types of nest

In 1960 I built my first artificial nest in Scotland using an old cartwheel at an old nest which had been vandalised.  It was never used which was not surprising, in hindsight, because I did not add any nest material.  In the last forty years osprey workers throughout Scotland have become much more involved in osprey nest management as the population has increased.  Initially, by repairing nests which had become damaged by storms, and then by providing new nests.  As the years have gone by we have changed to trying to make our built nests look as natural as possible for aesthetic reasons.

There are three main types of nest, as illustrated below: a) Artificial tree-type nest; b) Osprey nesting pole; c) Artificial structure.

Natural-type tree nest

Osprey nesting pole

Artificial structure

 

 

 

 

 

 

For further information on the different types of nest and instructions on where and how to build an osprey nest, read the following document:

How to build an osprey nest

 
In 2014 we worked with SSEN to erect an artificial nest on 25-metre pole in Angus to encourage a pair of ospreys to move from the top of an electricity pylon. The birds took to the new nest immediately and went on to breed successfully. Click below to watch a short video about the project.

Osprey nest build at Alyth from SSE Plc on Vimeo.