Friday, August 27, 2010

#12 Optics Tip: What do the Numbers Mean?

Every pair of binoculars is described by a set of numbers, for instance 8 x 42, as above. The first number refers to the magnification – the object will appear 8 times closer when looking through the binoculars. The second number is the effective diameter of the objective (front) lens in millimeters, meaning the size of the lens through which the image enters the binocular – 42 mm. The larger the lens size, the greater the field of view, and the brighter the image will appear.

In the case of binoculars, bigger is not always better! If you choose to use a higher magnification (i.e. 10 power) you may see the bird closer and larger, but the field of view will be smaller, and you must hold your hands very steady to keep it in focus. And a large lens size (42-50+ mm) offers a wide field of view, but the optics will be much heavier for it. Choose a pair that is most appropriate for your needs.

The number 7.7 degrees references the field of view, which in itself is not usually a decision-making factor for most birders.  And speaking of numbers, Nikon also includes the 7-digit serial number of the individual equipment on their optics, which is useful if you need to reference them.
photo © adrian binns

Friday, August 20, 2010

#11 Field Tip: Stop-Look-Listen

I have found that when out birding with friends or in group outings, be mindful of the amount of noise that you are making. We see and hear the most while walking quietly. Idle chatter reduces our powers of observation and alerts wildlife to our presence.

The sounds of nature are all around us, and we will be able to absorb them better if we talk less, pause often, and listen more.
photo © adrian binns

Monday, August 16, 2010

#10 Identification Tip: Dowitcher Structure

When scanning through a large flock of shorebirds, the first thing I do is look to see how many different sized birds there are. By looking at structure and shape I determine if the flock is pretty much all one species or made up of say, godwits, willets, yellowlegs, dowitchers and peeps (small sandpipers). We recognize these birds because they are of different size and postures. Just the way that you could recognize five family members, just by their silhouettes.

In this photo we have 3 larger birds which are American Avocets, and 4 smaller shorebirds mainly in feeding postures with their bills deep in water to their bellies, and one with a long straight bill.  Being considerably smaller, chunky looking, and having a long straight bill, makes it easy to call these dowitchers.  

Closer study shows some interesting observations.  Two of the birds - front left and back right - are noticeably larger than the other two, suggesting Long-billed's. The bellies of the larger birds are higher out of the water, meaning their legs are taller.  The structure of their bodies is bulkier and rounder (hump backed) than the other two; Kevin Karlson describes this as shaped like a tennis ball.  These are, indeed, Long-billed Dowitchers. Compare to the Short-billed's, whose bodies are more stretched-out,  oval shaped, and leaner.  These two points are often clear enough to separate and identify Long-billed Dowitchers from a distance, in silhouette.

For further information about dowitchers and shorebirds, I highly recommend the excellent book, The Shorebird Guide by Michael O'Brien, Richard Crossley and Kevin Karlson.
photo © adrian binns

Friday, August 13, 2010

#9 Backyard Tip: Study the Common Birds First

How well do you know a bird? Can you describe a common bird that you have seen a million times? Do you recall all the details of its plumage or field marks?

Take a moment to write down, or draw, what a Blue Jay looks like, and compare your notes to its image in a field guide and see how well you have done.

Start in your backyard and study the common birds first. Know them well. This will help in being able to identify similar looking and less common species, as well as enhance your birding skills and enjoyment of our wonderful passion.
photo © adrian binns

Friday, August 6, 2010

#8 Conservation Tip: Keep Cats Indoors

This is the only way cats should interact with birds - from behind glass! Outdoor cats pose a major threat to our bird population. Keep your cat indoors at all times.