These two questions are the same in scope. They are both (very simple) taxonomy questions. On the one hand we have "What are the names of these plants?", on the other we have "What is the name of this bird?" The difference is that one of them appears to have enough information to answer, and is not overly broad.
Bird taxonomy is fairly straight forward, with only a few hundred species of birds to deal with. Plant taxonomy has to account for several orders of magnitude greater diversity. An ornithologist only has to flash a few pictures to help the OP decide what they saw. The plant taxonomist might be able to narrow it down to Genus from a picture, give a common name, and then explain how they would need measurements/descriptions of the fruit, roots, and/or flower parts not present in the picture to narrow it down to a specific epithet.
We miss an opportunity to educate the OP on the diversity of plant biology, and how to ask useful questions relating to the subject in the future. Questions that are overly broad, or that do not have enough information to answer them should be closed, and the OP prompted to improve it or provide more information.
On the flip side, I suppose we could say that Gardening is a better fit for animal taxonomy as well. In the Gardening FAQ it states:
- identification, diagnosis or management of plant diseases, pests, or weeds
I suppose the bird is a pest in the same way the plants in question are weeds. ;)
I had some qualms about that question in the beginning, as I agree it's similar to the the plant species identification that was moved to Gardening and Landscaping.
However, I think we have to consider the way it was asked and answered. While I've never engaged an ornithologist in conversation, I imagine that the very naturalistic/observational perspective of the question in describing the location, the markings, and, later in the comments, the call of the bird, would be part of their scientific discourse.
The plant question, while valid, amounted to little more than, "I've seen some neat plants on vacation, tell me their names." This one had a stronger biological basis.
These questions do not fit into the StackExchange framework. They are idiosyncratic, personal questions, not questions of general interest. There is no way that anybody else with a similar question could find the relevant question.
The question could be appropriate if it is framed differently. Such as "what does a caterpillar look like" or "how does one distinguish among different types of caterpillars"