Growers flocked to Te Awa Winery recently for Fruitfed Supplies' Bird and Pest Control Field Day, where discouraging birds was the focus.
An arsenal was on display at 12 stations among the vines.
Field day representative Andrew McNeil said most research in New Zealand has concluded that in order to discourage birds, "anything other than a net is a waste of time".
"But you ask any grape grower that and they will emphatically deny it," he said.
An orange-and-black gun on display shoots Bird Banger and Bird Screamer cartridges and costs about $2 a shot. Ear protection is a necessity.
Another deterrent, the Mega Blaster, plays recorded predator and distressed-bird calls.
"There are some vineyards in Moteo that have had them for some time. They rate them quite heavily," McNeil said.
Another item on display was a gas gun, which provides a double deterrent.
As well as the sound and concussion, a mirror pyramid rotates and shakes as it fires.
The most impressive weapon was the Thermal Fogger, which uses the hot exhaust from a pulse jet engine to spread a gas that only birds find irritating.
"The food-grade additive hurts the respiratory passages of the birds.
"You use it as a tool periodically to keep birds out of the vineyard. Smoke comes out initially, but all it is doing is charging the air particles. Once it disappears, the food-grade additive is still in the air and moves throughout the vineyard.
"The active ingredient is naturally occurring in wine grapes, among other food crops," McNeil said.
Starlings, blackbirds, silver-eyes, wax-eyes and rooks are the main pests.
"Starlings are probably the biggest problem and you only tend to see rooks in Mataphero," he said.
Large birds swallowing whole grapes are preferable to small-bird damage.
"Small birds peck the fruit, which induces sour rot," he said.
In answer to a grower's question, if there was scope for a contractor to travel around vineyards discouraging birdlife to save all wineries investing in the same equipment, McNeil gave an emphatic no.
"Birds feed morning and night and you have to be on site at those times," he said.
Vineyards have different parameters when discouraging birds.
"There have been some self-imposed restrictions on shooting by a number of wineries that border cycleways and there are council regulations regarding noise close to a boundary," he said.
In his experience, he said white was the best colour for netting, because it acted as a deterrent.
"Birds can't see black and they tend to land on the cloth and, regardless of whether it is there or not, will peck into the bunch."
The sweeter varieties such as pinot gris, chardonnay, sauvignon blanc and especially gewurztraminer are most targeted, he said.
A vineyard close to the Bridge Pa triangle has six gewurztraminer vines accidentally planted in a merlot block with no netting, he said.
"Every year just the gewurztraminer are completely stripped by birds."