There is a group of people who can shapeshift. They send out hunting parties, scout teams, etc. In a circumstance where a group of ten people can look like ten different species (one human, one wolf, one demon antelope, etc.) is there any way they can communicate effectively across team members without having to change shape back to a species with greater vocalization ranges? Telepathy is excluded as an option.
The best answer would be that which allows for the most complex information to be shared in the most quick and efficient manner. For example, "scent glands" could feasibly be integrated into just about any form a person takes, and used to emit smells for communication, but one weakness as an answer is that it seems difficult if not impossible to convey more detailed information using this method. My benchmark for a useful method would be the feasibility of saying something basic, but with details, like: "two people, north, armed with spears, riding horses."
I should probably also clarify we are talking all generally "person-sized" animals here, not a three-inch-long mouse trying to communicate with a two-story-high dragon. The shapeshifters are limited in the extent that they can re-proportion their mass, and can only turn into physically possible animal species.
Edit: Some clarifications that came up in the comments.
For the purpose of this question, let's use humans as the baseline for the shapeshifters in their natural form, with all the assumptions inherent to them (possessing a developed verbal language, high intelligence, etc.) Any differences that suggest themselves as significant I will try to state and clarify as necessary.
The shapeshifters have some degree of adaptability, but have to start with an existing animal as a blueprint. basically they can't do anything not biologically practical. AKA you can start with a giant cat beast, then proceed to make the fur longer or change its color, change your build a bit, etc., but if it wouldn't be functional on the actual animal, it isn't going to work for you either, and may be prevented due to inbuilt shapeshifting failsafes. You probably can't add unbalanced tentacles to your giant cat, but you can likely make your tail longer.
There is an extent to which the shapeshifter's own inherent internal structure is required to be retained as well. For instance, the biological components (such as a shapeshifting-devoted internal organ, their brain, and their blood) related to the shape-shifting process can't be altered or eliminated. Nor can the shapeshifter's cells turn into anything not a natural organic part of their body. So, they can create hair (or fur), bone, skin, muscle, claws (or horns or tusks or scales) etc. etc. But they cannot turn a part of their body into metal, being non organic, or bark, since, despite being organic, it isn't made from the same sort of materials their natural body is (I think?). So while you might be able to shapeshift a bone exoskeleton or scales as natural armor when fighting, you couldn't turn your arm into a steel sword or your skin to iron.