Birds have been blamed for leaving thousands of ESB customers without power in and around Letterkenny, Co Donegal, yesterday morning.
About 4,000 customers were affected by the outage at 8am after a circuit-breaker tripped at the Cullion sub-station.
A spokesman for the ESB said something, more than likely birds, came in contact with a line at the sub-station, causing the power to automatically shut down.
However, power was restored within 20 minutes.
Earlier in the week two similar outages left up to 40 customers without power.
"The circuit-breaker tripped after something came into connection with lines, which was more than likely birds," the spokesman explained.
"We had three separate incidents last week in Meath, Limerick and Waterford where birds flew into sub-stations.
"I am not an ornithologist, but the weather tends to be poor at the time these incidents take place, and birds have been seen converging on the sub-stations, possibly for shelter."
He added that outages were a regular occurrence in Inishowen, where migrating swans crash into power lines near Inch Lake.
There could be up to 6,000 swans on the lake in summer, and as many as 4,500 geese during the winter.
Because of its geographical position, the lake acts as a kind of motorway service station for birds.
When they are travelling from as far away as Greenland, the first place they hit is Lough Swilly and then they come to rest at Inch Lake.
The ESB has been forced to install "swan deflectors" or large colourful balls on power lines around the lake.
Birds are not the only threat to power supplies.
Towns across the country are regularly hit with power cuts as a result of builders hitting underground ESB cables.
Two years ago in Moville, a man flying a light aircraft hit a powerline, causing a major outage in the area.
He was later prosecuted and fined at a local court.