Excellent Great that all the maps from all the Britain & Ireland maps are easily accessible. Simple to use. Obviously works best on a phone with a decent size screen, but can be expanded without too much loss of definition.
Great app Let's you check out bird species for where you are. I checked to see raven in the Midlands.
Excellent access to information at no cost. Easy to navigate and zoom.
eBird Mobile lets you record the birds you see, adding them to eBird with ease
HKcBirds: Common Birds of Hong Kong — Birds of Hong Kong in your hands!