One of the trickiest aspects of hawk identification is telling adult female from juvenile Northern Harriers at a distance. Most people are familiar with the rusty colored, essentially unmarked underbody of juveniles versus the paler buffy, streaked underbody of adult females. However, adult females can show rusty undersides (more commonly in the West) and appear very similar to juveniles, and the underside of juveniles fades to buffy by winter/spring and can appear similar to that of an adult female.

Before "clicking" on the composite above to enlarge it, note the overall color of the 4 birds as they would appear in the field. The 2 left-hand birds appear orangey underneath as you would see on typical juveniles, and the 2 right-hand birds appear buffy resembling adult females. Now enlarge the photo and see that the 2 adult females (1st and 3rd bird from Utah, November) show streaking on the body, and the 2 juveniles are basically unmarked on the body. The 2nd bird was photographed in September and the faded juvenile (last bird) was photographed in December in Utah. Consider that, if the lightly marked adult female was an orangey type, it would be nearly impossible to tell from a juvenile without ideal views.

Yes, there are other plumage differences between adult female and juvenile Northern Harriers (topside color, marked undertail coverts, head pattern, etc.), but they are minor and difficult to pick out without considerable experience. Telling Harriers from other hawks can be difficult, so classifying a "brown" Harrier as unknown age/sex shouldn't be a bother. Too often, I have seen birders 'shoot from the hip' when ageing Harriers never aware they were incorrect.

Ageing Golden Eagles to a specific year can be tricky because the amount of white in the wings varies in extent until adulthood when the white is absent, and wing molt can be difficult to assess without lots of practice. So, the best thing to key in on is the tail pattern and molt. Using the tail to age Golden Eagles is often much easier and more accurate than using overall plumage and wing molt. Of course be careful of birds with adult tails that have one or two secondaries with white at the base. In these instances, the tail has just been fully replaced of the last few sub-adult feathers, but the wings are one or two feathers behind. This occurs typically in birds that still have extensive white in the sub-adult remiges (secondaries and primaries), and take a bit longer to appear all-dark in the wings than some other Golden Eagles.

One more thing -- SY (2nd-year, meaning a year older than juvenile) sometimes only molt one or two tail feathers, a few inner primaries, and minimal body feathers, looking nearly identical to juveniles, so beware of scrutinizing every eagle. Anyway, I just wanted to talk a little about eagles, here are a few tails to check out, the first two birds are 2nd-years (note the several new sub-adult featherson the first bird but the second bird is only molting one tail feather), the 3rd bird has molted 3 times making it a 4th-year, and the last bird is an adult (but don't be fooled by that "slash" of white at the base of one of the tail feathers - adult GE feathers can still have a bit of white near the shaft (as can other species but often only seen in the hand).

It is mid-September and hawk migration is nearly in full swing! At every migration site, raptors pass overhead in a glide and identifying them on shape is a necessary skill. Red-tailed Hawks are blocky-winged and the primaries jut out from the trailing edge slightly in a shallow glide and a bit more in a steep glide. But did you know that juveniles exhibit longer wings and longer tails than adults? This is very useful information when telling the two ages apart in flight. Check out the picture below of the juvenile Red-tail on the left and the adult on the right, notice the primaries sticking further out on the juvenile, and the wings appear slimmer overall. You can also see the translucent primaries of the juvenile (the adult has pale outer primaries but that is a trick of the lighting in this particular instance - not retained juvenile feathers). Either way, this example shows the difference in shape, and also the difference in color. When seen from below, juveniles appear a simple black and whitish, adults have a pale orangey wash underneath and sometimes darker flight feathers that are often visible even at high altitudes.

Of course, some adults are more colorful than others, and some Red-tails are longer-winged than others by nature, so beware of ageing Red-tails by shape if you haven't practiced it. But use these traits when you feel comfortable, because they are deadly accurate once you "get it.'

Do all Red-tailed Hawks show dark patagials? Well, yes, but…

Dark patagials (or "patagial bars") is a well-known ID trait for light-morph Red-tailed Hawks, but some show very faint patagials, appearing as if they lack dark "bars" altogether. This is more common with juvenile Red-tails than adults, with Eastern Red-tails than Western, and on heavily marked Harlan's  moreso than heavily marked light-morphs of other races, but light-morphs of any age or race of Red-tail can show faint patagials.

On the other hand, there are very pale Red-tailed Hawks with bold patagial marks, so be careful to ID or dismiss an ID based on this one trait. Below are a few Red-tails with faint patagials and a few lightly marked birds with bold patagials. By the way, I have seen other people's photos that are even better examples than these. Enjoy!