A new home for house martins

House martins have declined woefully in recent decades. The figure quoted by the fifth Birds of Conservation Concern publication is a 57% decrease in numbers between 1969 and 2018. It’s because of this that the International Union for Conservation of Nature (IUCN) in reviewing the possibility of its extinction in the UK, has moved house martins from amber status species on the concern list to red status.

The reasons speculated include loss of insect food, habitat loss and climate-change related weather: for example, periods of drought making it difficult for house martins to find mud to make nests. The Leochel Burn runs along the east side of Craigievar Castle estate and it has a small wetland adjacent – a great source of mud. This freshwater stream and nearby livestock farming means insect life is varied and plentiful.

When house martins roost ahead of migration, their behaviour becomes flighty. What I experienced from my living room hide was a collective release of hormones. Along with shortening days, lowering temperatures and dearth of insect food, the hormones altered their behaviour and signalled it was time to undertake a big journey. And what a journey it is. On arrival in sub-Saharan Africa, the house martins will have travelled 3,000–4,000 miles. They will have bred, delivering perhaps two or three broods in the Scottish summer, and as food becomes scarcer with the turn of autumn, they will fly south.

Next spring, they will embark on the return journey and by the time they arrive in this country it is April. Along the way they will have encountered rainstorms, gale force headwinds, cold fronts, a scarcity of food, predation by other birds and mass hunting by humans over certain countries. Some of the youngest will not survive.

We wanted to give them somewhere safe to breed on their return to Craigievar after such an energetically demanding marathon. Out of necessity, the windows of the castle are being painted and repaired. Many of the levels are covered with scaffolding, netting obscuring the windows. Although we have left spaces where house martins can access their usual spots to build their nests, the work might prove too clamorous.

Which is why we have erected this house martin tower. Towers for swifts and martins have been popular in Belgium and Holland for a while, with studies evidencing success. However this is one of the first that we know of here in Scotland. We called on the expertise of Peak Boxes, a small firm with a big heart making well thought out bespoke bird boxes, and Huntly Swift Group – NES Swifts, the local swift and hirundine conservation group, to help bring the model to Craigievar.

Nature, Beauty and Heritage for Everyone is our mission statement at the National Trust for Scotland. This project embodies these values, galvanising conservation action in an aesthetic design and bringing together the talents of all ages in the local community.

Cromar Future Group, a STEM youth group are making a video of their work on the project, and have pieced together the ‘audio caller’ with expert support. Scientific studies in Belgium have shown ‘audio callers’ work in other setting, alerting passing birds to the suitability of a nesting site by emitting a recording of the bird’s call via small speakers.

To see the pole erected, and have the audio caller switched on and hear the audio of the house martins makes it real. We’re keeping our fingers crossed for the real thing to arrive and nest, but also know it can take a couple of years for artificial nests to be accepted.

SSEN (Scottish & Southern Electricity Networks) kindly donated the telegraph pole on which the box is fixed, and using a JCB they expertly manoeuvred it from the car park into the ground, as a small crowd of stakeholders nervously watched, while archaeologists checked there were no artefacts in the soil around this historic area. The tower is sited downhill from the castle, close enough for the house martins to associate it with their usual nesting place, yet distant enough to be sensitive to the castle’s heritage status.

Underneath its elegant octagonal canopy are house martin ‘cups’ recreated using a natural wood chip mix. And to reflect the fact we have bats who use the castle too, the house martin tower also features a void beneath its roof, a compartment separate from that of the house martins, with slots for bats to get in and ridges on which to roost.

The often-misquoted line from the film goes ‘Build them and they shall come’, to which the response is, ‘Ease their pain. Go the distance’. That’s what we are aiming for. Nature, Beauty and Heritage for Everyone – an ensemble effort – a testament to conservation, and a living sculpture.