If you want to combine the plants from two beds into one, you can do this easily using the bulk update feature. Here's how.
Steps
1. Create the new bed
If the bed is not already created, go to your site settings and create the destination bed — for example, "Birds".
2. Move all plants using Bulk Update
In the material list, create a filter for the beds you want to merge (e.g. "Hummingbirds" and "Songbirds"), select all their plants and use Bulk Update in the material list to change their location to the new bed ("Birds").
3. Delete the old beds
Once all plants have been moved, go to Site Settings and delete the now-empty beds ("Hummingbirds" and "Songbirds").
Tip: Activity log tracking
One benefit of this approach is that the location change is recorded in each plant's activity log. You'll be able to see exactly when a plant moved — for example, from "Songbirds" to "Birds" — making it easy to trace your garden's history.