Are there any beasts with an always-available bonus action?

Question

I'm currently playing a level 5 moon druid (PHB, p. 69), and I really like the call lightning spell. Unfortunately, it requires you to use your action repeatedly.

Now, I'm looking for a beast that I can (preferably at this level already) Wild Shape into, which has a bonus action available. This would allow me to use my action to activate call lightning every round, and still do other stuff besides moving.

I'm aware of several beasts that have abilities such as Pounce. However, these usually require you to use your action for an attack, which defeats the purpose of this question.

Similarly, I know that I can stay in my regular druid form and cast healing word with my bonus action, or that I can use a bonus action while Wild Shaped to expend a spell slot for healing. Both are, however, situational, expensive and undesirable (unless you want to get yourself or your companions hurt).

Are there any beasts that are able to use a bonus action without spending their action in a specific way?

Answer 1

The Cranium Rat has an "always available" bonus action, but I would not recommend it for combat. It is a tiny CR 0 beast from Volo's Guide to Monsters and all it can do with its bonus action is this:

Illumination. As a bonus action, the cranium rat can shed dim light from its brain in a 5-foot radius or extinguish the light.

I believe it is the only beast with an "always available" bonus action at the time of writing.

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Homebrew and UA aside, the only ways to get an "always available" bonus action for Wildshape are to multiclass into a class that grants you a bonus action (such as the Rogue), or to be one of the few playable races with a bonus action (such as the Goblin)... though of course it is too late for your character to be a different race.