Birds will eat the fresh leaf buds but the flowers can't say I know of any bird species that eats the flower buds perhaps not nutritious enough to spend the time trying to gather as after all this time of year nesting time you need something that is a lot more nutritious and easier to feed your brood with
There are no poisonous hawthorn bushes and flowers, leaves and berries can all be eaten - make sure its hawthorn.
Superstition says its very unlucky to bring in the house …… but that's because it smells like the decaying flesh (I kid you not!)
Humans get the upset tummy with eating the raw hawthorns but not birdies.
https://www.woodlandtrust.org.uk/vi...ritish-trees/a-z-of-uk-native-trees/hawthorn/