It was extremely bright sunshine, I'm never sure of the best way to handle highlights like this on their white feathers, but will try again tomorrow, any advice on the best way to go about it?
For general reference, I'd suggest reading a book like John Shaw's "Field Guide to Nature Photography." He gives some very basic and essential information on exposure, in an organized fashion, and will really form the foundation for achieving good exposures in the field.
For your immediate purposes, if you're shooting in Aperture Priority, the only way to adjust exposure up or down is to use EV Compensation, as I alluded to in my first post. In the situation you'll be encountering, the bright sun tends to really light up those white feathers. The camera's metering system is going to try and provide an overall neutral exposure. So while the overall image will be neutral, because there are extreme bright areas, these will be overexposed.
Depending on the intensity of the sun, you'll need to set negative EV Compensation, as little as -1/3 EV but more likely -2/3 to -1 2/3 EV. Check your camera's manual on how to adjust EV Compensation if you don't know how to do this. It is an essential adjustment that will need to be made in the field. You can check both the histogram and the "blinking" highlights in the thumbnail, to assess whether you've made adequate adjustment.
Have fun, and let us know how things work out!