Protecting Our Cherries from the Birds!

I didn't see many bees in the fruit trees this spring, but I guess they must have been visiting the flowers because we have a bumper crop ripening on the tree.

Cherries ripening June 22, 2018.

Of course, the birds are a real threat to edible fruit (robins seem to be the worst).  The tree is about 8m high and I'd be happy for the birds to eat the high, out of reach fruit, leaving the lower fruit for me.  But, I know that they will peck, sample and destroy all the cherries if given a chance.  So what to do?...

Previous years I tried aluminum pie plates, scarecrows, CDs, holographic tape, scare eyeballs and blue survey tape to try to scare the birds.  The performance of these options was poor to say the least.

The best solution was using a motion sensitive sprinkler to scare the birds.  It worked but wasn't ideal.  The motion detector really didn't see the birds and the only way to scare the birds from the fruit was to dial up the sensitivity to the photocell to enable the sprayer to work constantly.  The water use was excessive and the deterrent not terribly effective.  Also, the sprinkler used a fair number of 9v batteries.

Last year I decided to make my own sprayer deterrent.  I attached an irrigation solenoid valve to an impact sprinkler head and then I programmed an Arduino Pro Mini to activate the valve every 60 seconds.   I also built a photocell into the circuit to ensure the system only fired during the day -- the birds aren't a problem at night!  The new system worked well, but was only effective on the lower branches of the tree because the sprinkler was stationed close to the ground.  And the birds figured out the timing of the valve and would attack in the lull periods immediately following the sprinkler activation!  Smart birds!  The whole system was powered by adapter, so I saved a few batteries.  And the activation time of the sprinkler was shorter, so water usage was less than before.  But it still needed improvement.

This year I decided to upgrade, and added a second impact sprinkler/solenoid valve.  I've built a tower of irrigation pipe with sprinklers at 2m and 4m levels aimed into the tree.  The Arduino code now fires the sprinklers independently and at random intervals.  The lower sprinkler and upper sprinkler are also randomly chosen to fire randomly.

Irrigation valve and sprinkler head.

So far the birds seem to have trouble figuring out the cycle and the cherries are ripening nicely without bird losses.  The sprinklers use about 250ml each activation.  So daily use should be about 100 to 150litres.  I figure that I might water the tree anyway so this water goes to good use making larger, juicier fruit. 

Future improvements might be to reduce firing frequency during certain times, because feeding pressure seems to be higher in the mornings and evenings, mid day sprinkler activations could be reduced.  I intend to etch some boards and build a few more as I've got 4 more cherry trees on our property that are unprotected.  This year is looking like a bumper crop, so much so that the kids are going to set up a stand to sell some cherries.