Reptile & Amphibian Forums

Just thought I would share some more information Jud and I have gathered recently on the initial feeding of newborn green anacondas. This always seems to be a topic of conversation on this forum, as getting newborns to start feeding is a common concern many anaconda people have had to deal with. We have started and raised a fair number of newborn anacondas over the years and after working with this latest and largest group, a total of 28 young, our previous feeding experiences with young greens has shown a very similar pattern.

Only about 10% of these young fed within the first two months, and these took fresh killed or frozen/thawed young rats. All others refused fresh killed or frozen/thawed young rats, chick scented rats, or plain chicks. And as we have typically always seen, the young that didn’t feed were uncomfortable at the smell of rats, and usually pulled away from them fairly quickly. At three months, an additional 30% of the young had started to take either frozen/thawed chicks or chick scented rats. The other 60% still refused all offerings of any kind. Earlier this month, at almost four months of age, live chicks were offered to the other 60% of the young that had yet to feed, and all except one took the chicks within a few minutes. As of this week, at 4 months of age, a few of the chick feeders are starting to take chick scented rats, and a few of the ones that started on chick scented rats are just beginning to take unscented rats. All appear in excellent health with no sign of weight loss, even in the ones that have just started feeding.

The above feeding pattern appears to be typical and seems to be the standard with newborn greens in captivity. The main thing is not to panic if they go 4 or 5 months before feeding. Just keep offering food on a weekly basis, preferably overnight. We feel that if healthy and the proper environmental conditions are met, they will start feeding when they get hungry. If they were to go more than 6 months, I would probably start looking for a cause. However, I have yet to see a healthy newborn starve itself to death. Live chicks seem to be their favorite, and I have never seen one that could not be switched from chicks to rats within a few weeks using proper scenting techniques. Once they take that first meal, the vast majority of them take off, and never look back. Also, try to house them as simply as possible until they start feeding consistently, and always have a hide box available. We have been fortunate to be able to work with a fairly large number of newborns from different litters, and this has allowed us to be able to observe a wider range of individual feeding patterns. Hope this sheds a little more light on an interesting subject.

Kelly

Did you observe this behavior among yellow conda too?tnx

Unfortunately I don’t have any experience with yellows. Hopefully someone else here on the forum has raised fair numbers of newborn yellows and can help answer your question. I too would be interested to see how they compare to greens in this respect. Thanks,

Kelly

Did you offer any other prey items?

Maybe in the wild they begin eating fish, like baby alligators
begin eating insects and small fish.

We did not try fish this time, but I did try it with the 2001 litter and did not have any luck with it. I believe Jud used fish to start a young green many years ago, but from other sources I have spoken with or read, fish has only occasionally been used successfully to start young greens. I have also noticed that they do not start very well on mice either. I don’t believe it is only a matter of what you use, but also a matter of when. As with some of the other boids with slow metabolisms, like blood pythons, I just don’t think many of them are overly interested in feeding for the first two months or so. I also still believe that newborn greens are instinctively attracted to young birds. It seems likely that newborn greens would hang around shallow water near the shoreline for security. It is also a great place to take young ducks and shorebirds that would be abundant there in the tropics. They would be easy targets and would also be incapable of injuring the young anacondas when constricted. Additionally, as mentioned earlier, many young greens do show a slight fear of mammals for the first few months. This could possibly be an avoidance instinct against mammalian predators searching the shoreline for prey. However, I don’t have any hard evidence to back this up, just my opinion on it.

Kelly

Interesting - you may have something there, regarding aversion to mammals, at least somewhat.

I saw learned diets in larger juveniles (more than a year old) up to the adult males, preferred diet were wading birds, shorebirds, and turtles. Never fish. We only found one out of hundreds of captures with diet samples ever ate a fish, which injured him quite a bit (a spiny catfish, cut a hole through the small adult male's "neck". As the females got larger, ie. breeding size, they made a distinct diet shift to larger mammals and caiman, including capybara and white-tailed deer. Of course, prey items here were based on what was most abundant and present in shallow, highly vegetated waters, or on river's edges.

Finding baby anacondas in the wild is extre,mely difficult, but we did get a few captures that had eaten. I found a baby, probably ~ 3 months old, that had a mouse in its belly. Also, one time we had the misfortune of having a pregnant female at another field station ecnlosure, and a worker had left her cage open RIGHT before she gave birth. All 40 or 50-something babies escaped, but we found a few, and a few days later upon exploring her enclosure thoroughly again, we found a baby still in the cage, that had eaten a sparrow that had gotten trapped inside the cage. So, it ate the sparrow between birth and 5 days old!

I wouldn't even bother with fish. They just don't eat them in the wild, though it certainly has something to do with ease of capture.

Renee

Renee,
That is interesting about the newborn that ate at less than a week of age. We have had a couple over the years eat within a few weeks of birth, but it has definitely been the exception in captivity. I qualify “in captivity” because, without more in depth study on the feeding habits of newborn wild greens, we don’t know for certain if what we are seeing isn’t an artifact of captivity. Whatever the reason, newborn greens definitely show a relatively consistent initial feeding pattern in captivity. As you pointed out, it would be very difficult to study the feeding habits of a study group of young greens, in their natural habitat, over their first year. It would be interesting to see at what average age a group of free ranging newborn greens begin to take their first meals, and the species composition of those first few feedings. Your observations on the feeding habits of wild juveniles, seems to confirm what we have seen regarding the preference for birds.

The diet shift of our captive young from birds to mammals occurs rather quickly, usually within a few weeks or months after their first feeding. So it appears that their initial aversion to mammals is fairly short lived. Thanks for your information on the habits of free ranging anacondas, since so very few people have this first-hand knowledge.

Kelly

I hope to eventually have more info on this topic. We did radio track a few babies, but you can imagine with them being lunch for so many predators, it becomes a short-lived and expensive study. For example, we found the radios (only) that had been implanted below raptor nests, along the banks next to a bunch of caiman, etc.
Still, as radios get smaller and CHEAPER, I hope to do a longer term radio-tracking study on the babies, since they ARE big enough to do such a study.

Renee