I have been tracking the donations at the zoos on all shards since mid-November. It's been an interesting process overall; however, my overwhelming impression has been that many people feel that donating to the zoo is an exercise in futility. Attempting to use the zoo as an issue to pull a community together has worked on some shards; but on other shards it has not.
Individuals who have been around long enough to know about the zoo rewards and probably have the gold to afford them don't seem to be interested in dumping any more gold into the zoo to acquire more of them. Others who lack the gold to just buy the reward(s) they want are simply overwhelmed at the thought of the time it will take to earn a useful reward (e.g., donate 41 million gold or tame 11,000 unicorns or ki-rins to earn the 5-piece Zoo armor set). For many others, the zoo is something they know nothing about. If they do want to get more information about what can be donated and the rewards available by donating to it, they won't find such information on any site sponsored by EA....they must search elsewhere.
I do not know the exact rate of decay for the community collection points. However, based on the data I have gathered so far, it appears that the decay rate at a community level is approximately 18% per week. (Points acquired by individuals do not decay and also will transfer from shard to shard to follow the tamer, so to speak.) As best as can be determined, the only types of animals that can be donated to the zoo at this time are all types of wolves; slimes; polar bears; ki-rins, unicorns, nightmares, fire steeds; rune, giant, and fire beetles; dragons, drakes, and white wyrms; and reptalons. You cannot donate many other commonly used tamable creatures such as horses, ostards, ridgebacks, hiryus, or cu sidhe. And the points rewarded per category do not increase based on the difficulty or danger of the taming effort (e.g., you get 300 points for donating a beetle, regardless of whether it is a rune beetle or a giant blue beetle).
The very high rate of decay at a community level (which some may have assumed also applies to their own points), the limited list of animals that may be donated, the lack of useful rewards and information about what is available seem to be the biggest sticking points for getting more people involved with activities at the zoo as a shard activity.
I have been struggling for days to come up with some useful comments to add to this thread. I think there needs to be some amount of decay at a community level but 18% per week or whatever the true rate is seems excessive. I would also like to see the list of donatable animals expanded and the point values reevaluated so that the rewards are achievable for people who will never end up with mega millions in UO and don't have the time or the stomache to tame 10,000+ creatures to get something they will actually use on a daily basis.
I would also like to see some new twist added to the zoo at a community level. I've often thought that bricks or tiles with a donor's name on them scattered throughout the zoo would be an interesting addition. The color of the donor's name could change as they donate more points and a minimum (e.g., 100,000 points) could be required to earn the initial placement of a brick or tile.
Anyway, that's my two cents on the subject, and then some.