I've always left my inner tent door open, to allow animals to explore the tent without the need to chew through it.

Unfortunately. on the last day of a recent trip, an animal (probably a ground squirrel) came into the tent and chewed 6 small (~1 cm) holes in my down sleeping bag.

I've tried repairing one of the holes with a patch of tenacious tape, but I'm not convinced the tape will hold; after stuffing the bag, the tape seems to come up on the sides.

In the past I've sewn across the hole and used urethane to seal the repair; but these holes are a bit wider, with masticated fabric on the sides.

Any suggestions?

Send it to a repair shop and have them fix it for you.

The manufacturer will be able to recommend a good repair shop.

Trim the edges clean, patch it with any old fabric and sew the patches on with a zigzag stitch. If you're worried the fabric won't hold your stitches, you can reinforce it with a fusible adhesive (e.g. Spray 'n' Bond brand - not to be confused with their "basting" adhesive, which is a temporary hold to be used instead of pins).

You can get surprisingly good mileage out of tape. I've field-repaired my down jacket with duct tape, then keep forgetting to make a real patch, and it can last months before falling off. One trick is to carefully insert some tape into the hole and make a patch on the inside as well as the outside. You also want to trim the tape into a rounded shape; any corners will peel faster.

Thanks guys

There are some good suggestions here especially from nartreb. One thing to keep in mind is that to sew a patch to a down product will compress the inner and the outer layers together reducing the efficiency of the item. The zigzag stitching, suggested by nartreb, is a great idea since the micro filament nylon fabrics tear rather easily. Many home sewing machines have zigzag capabilities. I have also noticed sail makers have zigzag machines.

To avoid losing the loft in the down products you can carefully hand-sew through only the layer that is being repaired. Gluing the patch on first will help a great deal.

I'm trying several methods-- will let you know how they work. I'm not concerned much for aesthetics!

I've patched 6 of 6 holes so far, by different methods; one by tenacious tape alone; two (near the baffle sticthing) by stitching back and forth over the holes with the same colored thread, then sealing off the tear area with seamgrip; and two (on a dark part of the bag) by cutting out tough circles of no-see-um netting, top-stitching them onto the fabric above the holes, then saturating all with seam-grip, making a very down-proof and tough patch. The last hole, in the center of a baffle, I patched with a small round cicle of tenacious tape -- but I first put a glop of seamgrip over the opening, then pressed it hard to flatten all out-- the seamgrip doesn't extend more than half the radius of the tenacious tape. It isn't pretty, but that is the least of my concerns.

I guess in time you will decide which technique has worked out best for you. It would be nice to write up something, or just update this thread.