Cecil got scooped on this one. This was just addressed at snopes.com, the Urban Legends Reference Pages. Both articles are good, but you seem to have ommited one point, namely don’t mess with fledglings. I’ll excerpt the relevant bit:
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Possibly this widespread caution against handling young birds springs from a desire to protect them from the many well-intentioned souls who, upon discovering fledglings on the ground, immediately think to cart them away to be cared for. Rather than attempting to impress upon these folks the real reason for leaving well enough alone (that a normal part of most fledglings’ lives is a few days on the ground before they fully master their flying skills), a bit of lore such as this one works to keep many people away from young birds by instilling in them a fear that their actions will doom the little ones to slow starvation. Lore is thus called into service to prevent a harmful act that a rational explanation would be much less effective in stopping.
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So tell Jill to think twice before helping those baby birds.
Actual link is: http://www.snopes2.com/critters/wild/babybird.htm
Good work in advancing the cause against those foreign feline devils.