Tuesday, August 31, 2010

Molting Icterids

Blackbirds are notorious for looking absurdly messy at this time of the year, losing large chunks of tail and body feathers as they undergo prebasic molt into non-breeding plumage. Blackbird flocks are often quite shy, but this bird popped up long enough to grab a few shots. It's in very active molt with most body feathers freshly replaced, except the head which is just starting to molt. That's why the neck looks odd. The tail feathers are heavily worn adult feathers - very frayed at the ends. On the wings the secondaries are fresh and clean, but some primaries are still adult and yet to be molted in.

All sorts of things are going on with the plumage of this bird. That's one of the things that photography has improved my appreciation of - aging and sexing birds by feather age and structure, as opposed to just plumage color. This picture was taken on August 28th 2010 at the Brigantine Division of Forsythe NWR.

In this case it's not too difficult, since we can easily age the older feathers by fraying. (An alternative would be by shape since juvenile feathers are more pointed). Since they are heavily frayed in August this bird must be an adult (a bird born this past summer would not have this level of wear - it's feathers would be in good condition). The tail feathers in particular are very heavily worn. They are also brown, so these adult feathers belong to a female - the vast majority of birds molt flight feathers once, each fall, so these feathers are about a year old.

Over on the wing, there's a mix of fresh feathers and worn ones. The secondaries and some of the primaries appear to have been replaced, with at least one worn primary left from last year's molt. Ducks replace all their primaries at once, rendering them flightless for a while, but most other birds including passerines replace feathers in a more controlled stepwise approach.

And there you have it - not the prettiest bird in the freshest of plumage, but it speaks volumes about molt strategies.

There is also a difference in primary shape between the more pointed older feather and the more rounded new ones. This might be a difference between definitive basic and juvenile flight feathers (i.e. this bird is a little more than 1 year old), or this might just be a difference in feather structure due to position.

Update: on Sept 6th at Brigantine at least some Red-winged Blackbirds appeared mostly tailless, suggesting that their retrices were in active molt.

Tuesday, August 24, 2010

Juvenile Semipalmated Sandpiper

Nothing too special to say about this juvenile Semipalmated Sandpiper except that it's shots like this that make it worth crawling in the mud to get down close to bird eye level, covered in goose sh*t and bitten by Horse Flies. The bad days are when you get nothing at all, but it's often feast or famine at Jamaica Bay with a lot of random mixing of shorebirds. By the end of August juveniles are relatively common (this was taken Sept 1st 2008 at 7am) but they are quite scarce earlier in the season.

Update: this year I doubt I will be so lucky - recent rains have filled up the East Pond at Jamaica Bay leaving relatively little exposed mud as per birder reports. Some years this happens in early September, some years much later, but it's an unusual year for it to occur in August. The green "grass" here requires a few hot weeks of exposed mud to develop, so it won't be as lush as previous years and photo ops will be highly limited. The situation probably isn't enhanced by the laissez-faire attitude of the reserve staff on lowering water levels in recent years.

Juvenile Northern Mockingbird

You would think that since Northern Mockingbird is a widely dispersed common species that I'd have more photos of it. But apparently not. On a quiet day at Six Mile Run this was one of the few cooperative birds, and responded to my "spishing" by popping up and seeing what the hell was making that noise. I try not to lure young birds - in particular there was a quite recent Field Sparrow fledgling that I came across just after taking the picture above. I walked away from it rather than pursuing a picture because it was so very young (very short tail, weak flight) and I didn't want to stress it. Similarly the male Blue Grosbeak that I saw seemed somewhat agitated with frequent contact calling so I didn't approach it. That sort of behavior often reflects a predator response in the presence of young birds. This is how I act all the time - the birds are more important than my pictures of them - but all the more important that morning because a fast-moving adult female Cooper's Hawk was hunting the same area. Juveniles and first winter birds are often a little tamer anyway, so I prefer to wait for them to provide the opportunities rather than push them.

Thursday, August 5, 2010

Common Tern

Common Terns are coastal beach nesters whereas Forster's Terns nest in the saltmarsh. Accordingly at Brigantine there are a ton of Forster's Terns although the colony doesn't seem to be on the NWR - the fish-bearing adults headed out toward Brigantine Island. Common Terns are much less common yet I really have no problem finding them on trips at high tide. They like to hang out on one of the sluices, and I've seen up to 4 (usually it's one or two). That means there's perhaps a hundred more times Forster's than Common's, but nevertheless neither species is particularly annoyed by my presence - they're concentrating on the fish, or the Commons are ritually harassing the slimmer Forster's.

Other beach nesters that aren't too hard to find at Brigantine NWR are American Oystercatcher and Black Skimmer, although in both cases the numbers of these are relatively low too.

Osprey, Forsythe (Brigantine) NWR

There's an Osprey nest not far from the loop drive at Brigantine that's easy to photograph in morning light and the birds are accustomed to cars - not sure about people since I always shoot using mine as a "blind". Often both adults will be lounging around, but in this instance the (presumed female) made several flights into the marsh to pick up nesting material to work back into the nest, perhaps refreshing it after the accumulation of detritus. Both adults are far more agitated by fly-by Ospreys than they are by the cars, and in some cases it's not really clear why the other adults are doing such close fly-bys of an active nest. Surely Ospreys don't predate each other's nests ? There was a lot of vocalization but no actual direct confrontation.

Wednesday, August 4, 2010

Card speed in the 1D Mark IV

Recently my camera buffer filled up when I was shooting picture of Willet in flight. Needless to say that sort of thing really didn't happen very often with the sluggish 5D Mark II, but the 1D Mark IV is a different beast. Since Rob Galbraith appears to have slowed down or stopped updating his CF card database I'd become curious which were my faster and slower cards in my new 1D Mark IV and got a surprise. I did a test where I shot the camera until the buffer filled, and counted how long it took to empty the buffer (the red write light goes out). All cards were Sandisk.

CF Extreme 60 Mb/s 16 Gb - 9 secs - this card bought in 2010
Extreme IV 4 Gb - 12 secs
CF Extreme III 8 Gb - 16 secs
SD Extreme III 8 Gb - 24 secs
CF Extreme III 4 Gb - 24 secs

My cards are an "evolved" mix of different ages, so the older CF III 4Gb is several years old, the other cards one to three years old. Even with the same labeling the Sandisk cards have different speeds depending on their age. With the 1D Mark III the SD cards were comparable with the CF cards because the CF slot lacked UDMA compatibility, which was only introduced with the 1Ds Mark III. However the 1D4 has UDMA so the CF cards have become relatively a lot faster. At some point you do hit the speed limit in the camera card slot itself, of course.

The speed ratings from Sandisk's own truly unfriendly website show this story too:
CF Extreme Pro are 90 Mb/sec
CF Extreme are 60 Mb/sec
CF Extreme III and Ultra are 30 Mb/sec
SDHC Extremes are 30 Mb/sec in some versions
SDHC Ultra are 15 Mb/sec

These are current models, some of which seem to come in various grades, but the upshot is that Sandisk's very fastest CF cards are three times faster (!) than their fastest SD cards. The B+H site appears to be one of the better ones for surveying various CF and SD card rated speeds and their price points.

Slashgear tested CF cards in the 1D4 and show that you can get a 1D4 to write at 57 Mb/sec onto a card rated at 90 Mb/sec. That's slightly more than 3 images a second. It seems there's no point in buying an Extreme Pro card for speed - I'm getting roughly that speed with my regular Extreme - we've reached the inherent speed of the 1D4 card slot. Slashgear either didn't realize that or only had the fast cards to test. In their companion piece on SD cards, they get about 20 Mb/sec over all cards, which is around 1.2 images a second. Since the 1D4 usually fills the buffer with 33-34 images, the 24 seconds it takes my existing SD card to clear is pretty much par for the course. No room for improvement there.