Hi Catherine, so there is a forum topic that allows you to submits images for possible ID. It would be better however if we had a couple of good comparative images for the Collared Sparrowhawk and the Brown Goshawk that highlighted those key features you've mentioned- the position of the 1st knuckle, the brow and the square vs rounded tail.I know all these detail are in the books but sometimes actual images may make the comparisons easier.
So here is an attempt to compare and distinguish the features that are obvious and not so obvious in the 3 spp of Honeyeaters I photographed at Kingfisher Park this year.They can be an ID nightmare and I am sure there maybe plenty of people that may challenge my assessment. Kingfisher Park supply a great comprehensive sheet of notes to help us newbies to the area. So when comparing these 3 images.....
Lewins Honeyeater;- has a definite crescent ear spot, the area b/n the ear spot and eye is a grey wash and different from the colour of the crown and the gape forms a straight line with the pale yellow feathers beneath the eye. Iris blue/grey
Yellow-spotted Honeyeater;- has rounded ear spot, the area between the ear spot and eye is olive like crown, and the yellow gape and and feathers beneath eye are the same yellow colour and form a single line with a slight bulge. Iris brown
Graceful Honeyeater;- has rounded ear spot, the area between the ear spot and eye is olive like crown, and the yellow gape is obvious while the yellow feathers beneath the eye are poorly defined and do not form a definite line. Iris blue/gey. The bill is generally longer and finer with obvious down curvature cf the other 2 spp.
Of course in addition a good birder will know the differences in calls and behaviours. Gracefuls are extremely active when cf the other 2 spp.
So hopefully something like this might help people heading to the wet tropics ( or just make it even more confusing) Maybe someone more capable than me could tackle those dam raptors