There has always been a resident population of mute swans in and around Montrose Basin. The large area of mud exposed during low tide supports, amongst others, marine eelgrass (zostera species) which the swans love to eat. The reed beds provide safe nesting areas and the mud flats are a safe haven when the swans moult.
The numbers peak - sometimes up to 300 - when birds arrive on the Basin from surrounding areas to moult in July and August. When they moult their flight feathers in late summer, they become flightless for a time, and are vulnerable to fox predation. Foxes like to sneak up on their victim, but there is little chance of that out on the Basin's mud banks.
This immobility has been used to round-up swans as part of the research carried out by the UK Swan Study Group when the moulting adults and flightless juveniles were caught and ringed. A substantial set of data has been amassed that allows us to follow the movement of swans across the UK.
Before the reserve came into being they generally kept themselves to themselves, except perhaps when a breeding pair took up residence on the Mill Burn or the Tayock burn area, when they would defend their territory robustly!
In pre-reserve days they spent many of the winter months in the harbour area, eating the vegetable waste from the food factories. They only moved into the Basin itself in the summer months to feed on the eelgrass which grows in abundance on the mud. Since the reserve was formed in 1981 there have been changes in swan behaviour. These changes are a natural response by the swans to changes man has made to their environment.
In the early 80's the waste outfall from food processing activities was altered. The authorities insisted that the waste was decreased and the outfall changed so any food carried in it was now out of reach of the swans. Although this decision was perhaps a public health requirement, it had some unexpected side-effects. The swans now stayed in the Basin itself, looking for food after their summer supply of zostera finished in October until April when the zostera would regrow.
At around this time changes took place in farm cropping patterns. More winter-sown crops were grown, such as oilseed rape (the oil from which is used to blend into vegetable oil as an industrial lubricant and even as a bio-fuel), winter wheat and winter barley. So fields were now green during the winter.
Guess what the swans did next? You've guessed it - they came onto the farm land and started to eat the crops lovingly grown and nurtured by the farmer. So the swans now fed on farmland from October until May. Eating as much as a small sheep, a lot of damage was done.
For 10 years feeding the swans by hand was tried to keep them off the crops. Barley, wheat, vegetable waste... were all tried with varying degrees of success. The barley tipped on the Basin edge worked, but the large population of ducks enjoyed the free meal as well - they would get to the barley faster and clean it up before the swans got there! What's more, the swans were back on the fields immediately the barley was finished.
By 1998 something really had to be done. The result was "collective" compensation.
It was agreed that the local farmers would take turns, where crop rotation allowed, to have a "sacrificial" field which the swans would be encouraged to use. A field of oilseed rape near the "sacrificial field" would be used as a control and the swans kept off it. When the crop came to harvest, the produce from both the sacrificial and control fields would be weighed and any yield difference would be the result of swan damage.
The only fly in the ointment was how could we make the swans understand they were allowed in this field of oilseed rape and not that one? Swans, it turns out, are easily decoyed and a plastic swan, normally seen in garden ponds, was placed in the "sacrificial" field to encourage them to form a flock. A swan scarer was employed to scare the swans off any other field. It was a successful scheme.