Northern Harriers are Crepuscular?

[Steven Kersting]

Are they as active at sunrise as they are at sunset?
I'm having a hard time catching them with decent light available.

[John Chardine]

Hi Steven- I've looked into this a bit using the Birds of North America account for Northern Harrier as a resource. The quick answer is that this species is "diurnal", meaning it is active during the day. They are not especially active at either dawn or dusk ("crepuscular"). Harriers have facial discs of feathers akin to owls, which they use to enhance their ability to locate prey by sound. This is rare in other hawks. By the way, the Northern Harrier of North America used to be called the Marsh Hawk, and in Europe is called the Hen Harrier.

[Steven Kersting]

Hi Steven- I've looked into this a bit using the Birds of North America account for Northern Harrier as a resource. The quick answer is that this species is "diurnal", meaning it is active during the day. They are not especially active at either dawn or dusk ("crepuscular"). Harriers have facial discs of feathers akin to owls, which they use to enhance their ability to locate prey by sound. This is rare in other hawks. By the way, the Northern Harrier of North America used to be called the Marsh Hawk, and in Europe is called the Hen Harrier.

Well, I've spent several days stalking Harriers and I can definitively say they are more crepuscular. (Here's one resource that said so as well)

I found a location with 4 harriers (2m/2f) and at least 2 short eared owls....not sure if they are nesting but they are very consistently in the same location.

IME, they are Diurnal kind of like a house cat is. They will move around occasionally, but they mostly sit on the ground. But just before sunset they get quite active, and just after sunset the short eared owls pop up and it gets quite entertaining. About an hour after sunset the owls move off and the Harriers go to bed.

The location is a bit over an hour away and I'm not a morning person...... I just want to know if it's worth the effort.

Thanks for looking into it for me.

[John Chardine]

Are they as active at sunrise as they are at sunset?
I'm having a hard time catching them with decent light available.

Steven- You seem to already know the answer to your own question. Anyway, the following should clear up any confusion you have.

The question in the first line of the thread is a non sequitur in relation to the question you pose in the subject of the thread. In the subject line you ask if Northern Harriers are "crepuscular". The answer is no: they are not primarily active at dawn and dusk, which is the definition of the word. Northern Harriers are diurnal raptors (the third line of the write-up in the link you provide says the same thing). Diurnal means active during daylight hours, which does not preclude activity at dawn or dusk.

In the question "are they as active at sunrise as they are at sunset" you are asking a different thing. Diurnal activity patterns of animals vary a great deal through the day and it may well be that at some locations and times of year, harriers may be more active in the morning than the evening, or vice versa. In one winter study I am aware of from Ohio, males were more active in the morning and late afternoon while females and immature birds showed an activity peak sometime during the day.

If you are finding that harriers in "your" location are more active at dawn and dusk, this may be due to variables such as competition with other predators and availability of prey at that location and time of year. However, perochial observations like this do not make the whole species "crepuscular".

[Ian Cassell]

This is interesting stuff! BTW, John, you just cleared up something for me. My dad was an avid falconer and general raptor afficionado and I had heard the term 'Marsh Hawk' often as a kid. I got active in birding only a few years ago and haven't heard anything of marsh hawks since I started, but have heard a lot about northern harriers (which dad never mentioned). I didn't realize there had been a name change.

[John Chardine]

Yes Ian, and here's some more (from my early A Field Guide to the Birds by R.T. Peterson):

Duck Hawk = Peregrine
Pigeon Hawk = Merlin
Sparrow Hawk = American Kestrel

[Ian Cassell]

Thanks, John. Those three I already knew and they were used interchangeably. I had never heard 'harrier' used before to refer to a North American hawk. Actually, I believe there are many Sparrowhawks in the genus Accipiter outside North America (our Kestrel, however, is genus Falco, right?).

[Steven Kersting]

Well, I don't "know" how active they are in the morning...I only know these several are much more active at evening than during the day (male and female)...Like I said, I'm not a morning person. Guess I'm just going to have to get up early.

I thought crepuscular meant primarily active at dusk/dawn which doesn't preclude activity during the day...

But based upon the one study it sounds like it could be almost regional, individual, seasonal. I've never found Harriers (or short eared owls) before so this is all new to me.