(SCMP) - Why do vines grow grapes? Clearly, it's not to ensure that we get to crack open a perfectly chilled glass of albarino with our oysters. That is simply a rather pleasing side-effect. What vines want is a fail-safe system for ensuring their own survival, and they have chosen, in nature's wisdom, to wrap their seeds within perfect sugar-filled pouches tantalisingly displayed in easy reach of birds who eat them and eventually pass the seeds, thus naturally propagating the species.

For those of you who are still with me, the point is that grapes are pretty much irresistible to birds, particularly at this time of year, when they are heavy with sweet juice, glistening in the sunshine. The race is on for who gets to them first - the harvesters with secateurs at the ready or the starlings, sparrows, finches and jays, hungry for that rich ripe fruit.

Depending on the region, winemakers have different strategies for dealing with birds and protecting their profits. The most common, seen often in Argentina and Australia, is netting. These can be high nets spread horizontally a few metres above the vines, or softer mesh draped over each row. The drawback is that netting is expensive - up to US$740 per hectare - and it can reduce the amount of sunshine reaching the grapes, one of the key reasons why netting is banned in most appellations of France.

A few wineries, such as Vynecrest in Pennsylvania or in Willamette Valley in Oregon, go for a more hi-tech version of a scarecrow; blasting sirens, or even recordings of birds in distress, from weather-resistant speakers across the vineyard, in the hope of scaring birds (and just possibly visitors) away.

Others go slightly more old school, and rather than employing recordings of birds, go straight to source. It might sound like something out of Harry Potter, but increasing numbers of wine estates hire trained falconers to harness the power of birds of prey and naturally scare away grape-eating smaller birds.