I wouldn't do it to the chickens or the turtles neither of which are likely to be searching above head height for insects.
Better to move your hornworms to their own tomato plant and hope they are found by brachoniid wasps which lay their eggs along the back of the worm and paracitize(sp) it when the eggs hatch. We need more of these smaller wasps as natural controls of the hawkmoth larvae.

thanks for the thoughts, dottie. The argument against that is i definitely have seen chickens watch over their heads and actively work to get things there- and hornworms could easily be within their range naturally. Not everyone stakes maters, and i know that boxers can get a taste for maters and become real pests, eating a hole or 2 out of every one within reach. I assume it's on the nonstaked plants, b/c even an adult wouldn't be tall or agile enough to get at any but the first set on staked maters. But, if there are unstaked maters, then hornworms could easily be in reach of both turtles and chickens. Also, if chicken or turtle finds a pupae of a moth, they'll gobble it faster than you can blink, and hawkmoths along with many others, pupate directly in the ground.

I always do leave the cats who have the wasp pupae cases on them, but it's maybe a 1 to 15 ratio- and i'm not about to let that many unaffected hornworms reach maturity. When they show up for me, they show up in mass numbers. Plus, they are so damaging. I love to watch the hawkmoths in the evening go about their business, but i figure there's enough that slip through or are on the wild solanacea plants that can supplement the population. I've seen hornworms eating on some strange things, too- sunflowers, buddleia, etc. I usually leave those be unless they are doing extreme damage or are in high numbers. There are several different species, so they may be other ones or their tastes/tolerance may range wider than is commonly thought.

I guess my ? was more on the line of would the natural chems from the tomato plants hurt the chickens via the hornworms? Right now it's not an issue but i'm part of a community garden that has lots of maters and also a flock of chickens. I was asking so that down the rd when the hornworms show up, we know if we can give them to the chickens.

digging deep into Google I found some interesting info - "There are cryptic species, which metabolise or rapidly excrete the toxic substances present or avoid their ingestion by selective feeding; aposematic or warningly coloured species which store plant toxins in their tissues unchanged or slightly modified4"

Basically what I think they are saying is that some caterpillars hide on their host plants (like a tomato hornworm which blends into the green of the plant). These types of larvae tend to NOT store the toxins found in their food source, they expell it through their skin or through their waste. Their bodies would only be mildly toxic. The caterpillars that are brightly colored and stand out in their environment are the type that store up the toxins and are much more toxic to predators.

Now, how much tomato leaf toxin does it take to sicken a chicken, that's the question - toxin levels vary from plant to plant and leaf to leaf and if the caterpillar were large and had a gut full of leaf bits it could possibly have enough toxin to cause a problem. I found no evidence that anyone had experienced a death due to tomato hornworm eating - in any type of livestock, pet or child.