are known to feed primarily on the seeds of pines and other conifers.
They use their tongue and peculiarly shaped bill to remove the seeds
from the cones and this makes them pretty unique.
On 12 May 2020, I came across a small flock of Red Crossbills Loxia curvirostra
(type C) near Bergen in North Holland. Among them were several
juveniles. As they seemed to be foraging high up in a couple of oak
trees, I did my best to find out what exactly they were after. I then
came to the conclusion that the juveniles were eating from oak apples
and leaf buds.
That oak apples are produced by gall wasps, was about all that I knew
about them. After a quick search on the internet, however, I learned
that this particular species is called Oak Potato Gall Wasp Biorhiza pallida.
The oak apples are formed after the gall wasp lays eggs inside the leaf
buds and the plant tissues swell as the larvae develop inside. The gall
provides a nutritious and protective environment for as many as 30 larvae.
I am quite certain that I will never become an expert on gall wasps or
oak apples, but to get
out and learn new things is what makes birding so
interesting to me. Besides, watching young crossbills in action is very