Mama bird will most likely come back. I would suggest watering by taking the fern down and carefully watering around the nest, using a watering can without a spray head. This will be tricky when there are nestlings in the nest. A robin built a nest in my peach tree one time. It wasn't watering that was a problem for me but spraying the tree with pesticides. If you don't spray a peach tree, your peaches will have worms. What I did was to spray only the lower limbs below the nest, very carefully. Sometimes it is hard to decide how much you want to save something - bird or plant.

A pair of House Finches nested in one of our hanging ferns last year. I carefully watered around the edges of the fern whenever I found the Moma Bird away, staying away from the nest using a watering can without the spray head like vsjo mentioned. The whole process - eggs to fledging took about 4-5 weeks. I enjoyed observing them and had decided to give up the fern if necessary rather than disturb the nest. The fern looked a little sad by the end of it, but recovered quickly when the Finch family moved on.

You can also put a couple of ice cubes away from the nest, and they will melt to provide water for the fern without making the nest itself wet. In this weather, (HOT) it probably needs to be done at least twice a day!

SHE'S BACK! Hubby saw her fly into the fern. The ice thing is a great idea...I use them for baskets/pots that have dried out to much and the water runs right through. Thanks.

Will the hard rain hurt the newborn birds