What's the duration of these wild feats?

Question

The Benefit of the Complete Divine wild feat Serpent's Venom says

You can spend a usage of wild shape to gain a secondary bite attack (at your base attack bonus −5 and adding 1/2 your Strength bonus) that deals bludgeoning, piercing and slashing damage equal to a dagger appropriate to your size (1d4 for Medium, or 1d3 for Small). In addition, the bite delivers a toxic venom (Fortitude save DC 10+ 1/2 your HD + your Con modifier; 1d6 Con/1d6 Con). (84)

The Benefit of the Races of Stone wild feat Stone Form says

As a standard action, you can spend one of your uses of wild shape to assume a stony and rocklike form. While in this form, you gain a +4 bonus on Fortitude saves against poison. Your natural armor bonus becomes +4 (replacing any natural armor bonus you normally have, though you retain any enhancement bonus to natural armor).

You also gain a slam attack that deals bludgeoning damage equal to a morningstar appropriate to your size (2d6 points for Large characters, 1d8 points for Medium characters, 1d6 points for Small characters). (144-5)

None of the descriptions of wild feats that I've found (e.g. here) mention a standard duration for wild feats (in fact, many wild feats have unique durations explicit in their Benefits), despite wild shape itself having a duration.

Assuming there's no secret errata for these feats (the Complete Divine errata doesn't mention the first feat, and there is no Races of Stone errata), is the duration of these effects either instantaneous or as per the wild shape use expended to activate the Benefit or determined in some other way that I've overlooked? While a rules-based answer is preferred, if that's unavailable or distasteful, house rules for handling these feats are acceptable.

Answer 1

For Serpent's Venom, the feats table entry on p. 78 in Complete Divine states:

Gain a poisonous bite attack for 1 minute

This was easy.

For Stone Form I can only speculate. I'd say that if a wild feat states that you "assume a [...] form" it works as the Wild Shape ability, with the form specified in the feat. For Stone Form, note that:

Normal: Without this feat, a druid can only use wild shape to assume the form of an animal, plant, or elemental.

Which suggests that stone form is just another option for wild shape, with a duration typical for druid's level.

OTOH, wild feats that don't mention assuming a new form, should have specific durations. Again, look at the general description of Wild Feats (Complete Divine, p. 79):

You may only use the wild shape ability to change form or activate one wild feat per round, though overlapping durations may allow you the benefits of more than one wild feat at a time.

Overlapping durations may suggest that these durations are variable, there is no general rule for all wild feats.

Summary:

• Serpent's Venom: 1 minute
• Stone Form: as wild shape of your level (probably)