This is a study about the presence of arthropod (a type of insect that has an exoskeleton, segmented body, etc - like ticks, fleas and mites) hormones in wild birds bloodstream and how it affects them. Obviously, our birds, not being usually exposed to these external parasites, would not have the hormones BUT the interesting thing is how hormones that are specific to other animals or plants (think soy!) can still affect them.
https://www.nature.com/articles/s41598-019-53090-9




