Last day

Seven more raptors for the last day of the season, for a final total of 15,042 raptors this season. Two Turkey Vultures, one Bald Eagle, two Northern Harriers, a Northern Goshawk and a Peregrine Falcon were added to the count today.

Here are the season's totals:

Turkey Vulture: 370
Osprey: 56
Bald Eagle: 400
Northern Harrier: 522
Sharp-shinned Hawk (pictured above): 8,499
Cooper's Hawk: 51
Northern Goshawk: 69
Red-shouldered Hawk: 57
Broad-winged Hawk: 2,366
Red-tailed Hawk: 1,308
Rough-leged Hawk: 798
Golden Eagle: 89
American Kestrel: 322
Merlin: 64
Peregrine Falcon: 59
Swainson's Hawk: 2
Unidentified raptors: 10

I want to thank everyone who made my season at Whitefish Point more pleasant. Thanks also for the many positive reactions on this blog.

John

2009: a slightly below average year

With still one day to go for the 2009 season, looking back on it might seem premature, but believe me: that last day is not going to make much of a difference. Hawk migration has been slow for a while now, with the last good raptor flight dating back to May 21.

Looking at the number of raptors counted for all species combined, 2009 was a slightly below average year. Over the last 20 years of counting, the average count for Whitefish Point is about 16,500 raptors. 2009 falls about 1,500 short of that average.

However, more species had a better than average year than below average. In fact, 6 species had a season with numbers well above average; 1 species was slightly above average; 4 species were about average; 1 species was slightly below average; and 4 species finally were well below average.

Better than average:
The six species that fall in this category are Turkey Vulture, Bald Eagle, Northern Harrier, Red-shouldered Hawk, Golden Eagle and Peregrine Falcon.

Turkey Vulture numbers have increased at pretty much every Great Lakes and Northeastern hawk watch, as a result of a range expansion that probably started in the 1950s and is still ongoing. In the late 80s and early 90s, counts at Whitefish Point often stayed below the 100 mark. These days, seasonal counts of around 300 or 400 are the norm. 2009 so far had 368.

Bald Eagles are increasing after near-extinction only decades ago. 2009 ranks fifth in the series 1989-2008; all four previous years were (slightly) better.

The 2009 season also ranks fifth best for Northern Harrier, with 520 counted this year, a few more than last year.

2009 is one of only five years in the last 21 that had more than 50 Red-shouldered Hawks. This year's total reached 57, a few more than last year.

This was easily one of the best years for Golden Eagle (pictured above), second only to 2000, when 92 were counted. This year the count reached 89, many of them juveniles.

Peregrine Falcon too had a good year, with 58 for fourth best season ever. Another bird that's making a tremendous come-back after reaching near-extinction in the second half of the last century.

Slighty above average
The Rough-legged Hawk had a year with slightly above average numbers, about 12% more than average. The 2009 count got to 798.

Average
All three accipiters had an average year. This actually comes as a bit of a surprise to me, because I thought that Sharp-shinned Hawk did poorly in 2009, while it seemed a good year for gos and coop's. Against long-term data (1989-2008), these three species however did just about average. Sharp-shinned Hawk was 6% above average, while Cooper's Hawk was 5% below average, and Northern Goshawk 3% below average. I know that the raptor banders that band very close to the count site had one of their best Northern Goshawk years in recent memory, so it's curious to note the difference.

Swainson's Hawk also had an average year, with 2 counted.

Slightly below average
Red-tailed Hawk was slightly below average in 2009, by about 13%. Their count reached 1,308.

Below average
For Osprey, 2009 was well below average, by 55%. This is the second worst season on record for this species; only 2006 was worse, with 42. This year, 56 were counted. The average for Whitefish Point is 123.
Broad-winged Hawk had a low spring too in 2009, although the count was practically the same number as last year. It may be interesting to note that all three major North American count sites for this species - Lake Erie Metropark, Corpus Christi and Veracruz - had low numbers of broadwings last fall.

Finally, the two small falcons - American Kestrel and Merlin - had a low season this year. For kestrel, less than half the number of last year were seen this year, and the count this year falls 37% short of the 20-year average. For Merlin, a factor may have been that a pair had a territory very close to the hawk watch. I saw both adults constantly, and decided not to add sightings to the count when it was obviously one of these two birds, for example when the bird flew by calling loudly, or when it was seen flying back and forth constantly. Undoubtedly, some true migrants may have slipped through this way.

Tomorrow, when the season is officially over, I'll post the official count results here.

Listening to a Chipping Sparrow

Recently, when a group of second-graders visited the hawk platform, I was barraged with questions. They all wanted to know what I was doing, what the telescope was for, how many birds I had seen, did I live here, etc. etc. I guess one of them had observed me for a while, when he flat out asked me:

“Is this job boring?”

Perceptive kid, I thought. “Well, it is, sometimes,” I admitted.

Today, for example, the hawk flight amounted to 11 birds. For a full 8 hours of observation, that’s not much. Boredom definitely lurked, but I found some diversion in listening to a Chipping Sparrow that has established a territory right next to the hawk platform, but hasn’t found a mate yet.

Flipping through old issues of Birding the other day, I came across a review by Paul Hess of an article on the song of the Chipping Sparrow, written by Wan-Chun Liu and Donald Kroodsma, and published in 2007 in The Auk. Liu and Kroodsma looked at variation in the Chipping Sparrow’s song, and found that the species has two song types with distinct social functions. The dawn song is a fast series of short songs – 21.6 songs per minute, of 1.2 seconds length – while the daytime song is longer, and more widely spaced. The dawn song, sung from low perches, serves to advertise territorial boundaries and is primarily aimed at neighboring males, while the daytime song, sung from high perches, is aimed at attracting a female. Once paired, males stop singing during the day, but continue singing the dawn song – for as long as there are neighboring males around. Removing a bird’s neighboring males caused it to cease singing its dawn song; when the neighbors were returned, the bird resumed its dawn singing (Liu & Kroodsma 2007, cited in Hess 2008).

The Chipping Sparrow near the hawk platform is still unpaired, and sang throughout the day, or at least until 3:30 PM. Liu and Kroodsma found that the daytime song is not abruptly different from the dawn song, but rather that the bird tends to gradually sing longer songs, and fewer songs per minute, after sunrise. I started counting the songs of ‘my’ Chipping Sparrow at 9:56 AM, well after sunrise. I counted for three-minute intervals, and found him singing 16 songs in 3 minutes at that time, i.e. 5.3 songs per minute. About an hour later, I sampled another three minutes of his song, and this time found him singing 14 songs, or 4.7 songs per minute.

Then, at 11:25 AM, he was singing 6.3 songs per minute, while at 11:53 AM, he was back to 5.3 songs per minute. After noon, he took a long breather but resumed his singing at 1:30 PM with renewed vigor, now singing 7.0 songs per minute! The songs were getting longer too, from 2.5 – 3.5 seconds to almost 4 seconds for some songs now. He was keeping it up and 15 minutes later was still singing 6.7 songs per minute. At 2:45 PM I sampled his song three more times, and now heard him singing 7.0, 6.3, and 6.0 songs per minute respectively.

Liu and Kroodsma found an average of 6.4 songs per minute for daytime singing of Chipping Sparrows in Massachusetts. My Michigan Chipping Sparrow today sang on average 6.1 songs per minute. He actually sang slightly more songs – with more variation in song length and length of pauses between songs – later in the day.

All in all I timed 164 of his songs, but he probably sang more than 2,000 today. The ones I heard were all meant to attract a mate. Whether a female, so perceptively described by Kroodsma as “the silent architect of the male’s song” in the latest issue of Birding, was listening or not, I don’t know.

But today, I was.

Literature cited:
Hess, Paul (2008) “Chipping Sparrow Songs” in “News and Notes” section of Birding, Volume 40, Number 1, January/February 2008. (A review of a 2007 article by Wan-Chun Liu and Donald E. Kroodsma in Auk 124:44-52)

Peregrines and goshawks

Today's hawk flight was practically a rerun of yesterday's, with a couple of new plot developments thrown in by way of 2 adult Peregrine Falcons (one pictured above) and two immature Northern Goshawks (one pictured below).

Other raptors added to the count today included 6 Turkey Vultures, 2 Osprey, 3 Bald Eagles, 4 Sharp-shinned Hawks, 1 Cooper's Hawk, 31 Broad-winged Hawks, 15 Red-tailed Hawks, and 1 Rough-legged Hawk.

On roughlegs

With the Rough-legged Hawk flight practically over, I realize that a blog entry on roughleg ID comes a bit late in the game, but hey - better late than never. Earlier in the season I didn't have all these photos yet.

Sunday's flight was unremarkable, so I'll just give you the numbers, and we can move on: 8 Turkey Vultures; 1 Osprey; 1 Bald Eagle; 4 Sharp-shinned Hawks; 1 Cooper's Hawk; 51 Broad-winged Hawks; 8 Red-tailed Hawks. That's right - zero Rough-legged Hawks! Somebody mentioned they saw one, but I didn't, and so... ha! doesn't get added to the count. That's how that works.

In North America, the Rough-legged Hawk breeds in the tundra and taiga of arctic and subarctic Alaska and Canada, and migrates across the boreal forest to winter in open country of southern Canada and northern United States (Bechard & Swem 2002). Whitefish Point is an important migration monitoring site for this species, and in fact holds the record for most roughlegs seen in a day (525 on April 23, 2000) and in a season (2,600 also in 2000) of all North American hawk migration count sites.

The Rough-leged Hawk shows a tremendous amount of variation in its plumages. Unlike other members of its genus (buteo), it even shows distinctive plumage differences based on sex, as well as age, and color morph. Let's review some of these plumages.

The bird shown at the top is probably the most characteristic plumage, with the bold carpal patches ('wrist patches'), the dark belly and the white tail with the broad dark terminal band. These are the field marks that most birders associate with this species. They are the field marks of an adult female.

The adult female is quite similar to the juvenile, but note on the adult female the darker markings on the underwing coverts (roughly the feathers between the belly and the carpal patch), and the dark trailing edge on the wing. The black terminal band on the tail is also more defined on the adult female, as compared to the juvenile.

Here is that juvenile. Note the unmarked underwing coverts, the absence of a dark trailing edge on the wings, and the less neatly defined tail band. That last field mark is harder to observe on a closed tail.

Now let's look at an adult male.

Compared to the female, we note that the carpal patches are less defined, that the belly only has some barring on the sides, not the solid black patch of the female or juvenile, and that the head is darker. The terminal band on the tail of males is well-defined but thinner, and often males show a few extra bands near the terminal band. On this bird, the two outer tail feathers appear to be free of extra banding, but a hint can be seen just above the terminal tail band in the middle. If this bird were to spread its tail, we would probably see one or more extra bands.

So much for the light morphs. This species also has a dark morph, and an intermediate morph. Dark morphs are rarer than light morphs, and intermediate morphs are rarer than dark morphs.

Here's an adult male dark morph.

It's a beautiful bird. Note the extra banding on the half-open tail. That, and the fact that the bird is pitch black, make it an adult male. Only the adult male dark morph is truly black.

Here's an adult dark morph that could be male or female. The dark trailing edge of the wings means that it's an adult, but in the dark morph roughleg, dark chocolate birds can be male or female. I'm inclined to say that's probably a female, given the tail pattern. It seems as if there is no additional tail banding besides that broad terminal band, but these things are hard to judge on closed tails.

Finally, a juvenile dark morph. There is no dark trailing edge to the wings, so it has to be a juvenile. The carpal patches and the dark belly are well defined.

This far I've only talked about plumage. On distant roughlegs, when plumage is not yet visible, a first clue will often be the way they hold their wings in a glide: the so-called modified dihedral, with wings raised but the outer parts of the wings held flat. They are a little bit longer winged than the Red-tailed Hawk, and from great distances can appear similar to Northern Harriers - especially males.

Literature cited:
Bechard, Marc J. and Theodor R. Swem. 2002. Rough-legged Hawk (Buteo lagopus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/641

Unsatisfying looks

A decent variety of hawks was observed today from the hawk platform, although few of them provided very satisfying looks. Two immature Northern Goshawks made brief appearances, one of them attracting the attention of the locally nesting Merlin, who loudly told it to go somewhere else. In the photo above, taken a couple of weeks ago I think, an American Crow is escorting an immature Northern Goshawk toward the boundary of the crow's territory. That crow is nesting close to the hawk platform, and any raptor that flies low over that point gets mobbed.

A juvenile Golden Eagle was also briefly seen. Most tantalizing sighting was that of a probable dark morph Swainson's Hawk. It was a speck in the scope, it never got close, and when I lost the bird way out low over the tree line, I was 90% sure it was that species. It was really too far for a reliable ID, and sometimes you just have to let them go unidentified.

Another curious and ultimately not very rewarding sighting - but at least closer - was that of a Red-tailed Hawk with a nearly all-white, unbanded tail - with one red tail feather in there! The wings lacked a dark terminal band. I have to consider the possibility that it was a juvenile redtail that had just started replacing its first tail feathers, but I am quite sure the tail feathers were grayish white and unbanded - altogether wrong for juvenile redtail. I didn't see any obvious molt on this bird anywhere. I"ve seen so many odd-looking redtails here at Whitefish Point now, that's probably the one thing I'll remember most about this place.

Alright, count results: 1 Osprey; 7 Bald Eagles; 13 Sharp-shinned Hawks; 2 Northern Goshawks; 10 Broad-winged Hawks; 4 Red-tailed Hawks; 1 Rough-legged Hawk; 1 Golden Eagle; 1 Merlin.

Besides the Chaffinches mentioned yesterday, a European Goldfinch was also seen again today around the feeders. One of our blog readers posted a comment with a link to a very interesting article on European Goldfinches in the Great Lakes region that appeared in North American Birds last year. Apparently, a great many sightings can be traced back to a series of releases from the Chicago area. The following excerpt from that article just blew my mind: "As long as the birds are legally imported, there is no federal law prohibiting their release. Nor are any Illinois state laws targeted at the release of non-native birds." Not sure what the legal situation here in Michigan is, but I assume it's probably not very different. It seems very much a federal issue anyway, since birds do not recognize state borders. The last sentence in that article reads: "Citizens will have to apply considerable pressure to their state and federal legislators to encourage laws that prohibit the release of any non-native organisms if intentional introductions are to be prevented in the future."

Stragglers

It's late in the season, and hawks aren't exactly in a hurry anymore to get to where they are going. The ones that were, got there already. So today's juvenile Peregrine Falcon criss-crossed Whitefish Point air space throughout the morning, before eventually taking off. Most of the raptors now are juveniles of course, like for instance all of today's 8 Rough-legged Hawks (juvenile intermediate morph pictured above). Other raptors seen today included 1 Osprey, 4 Bald Eagles, 1 Northern Harrier, 10 Sharp-shinned Hawks, 19 Broad-winged Hawks, 6 Red-tailed Hawks, 1 American Kestrel, and 1 Merlin.

There appears to be a small influx of Chaffinches going on at Whitefish Point at the moment. Riding my bicycle to the count site, I already saw one male along the road, and when I got to the Point, there were two more males countersinging on either side of the parking lot! How crazy is that? To my European ears, this sounded like home, but I met birders who were puzzled by their loud, emphatic songs. These birds are almost certainly escaped from captivity, as no wild birds have ever been documented on this side of the Atlantic, and (therefore) North American field guides don't even feature them. Earlier this season a male was seen with a female near the feeders behind the Owl's Roost, and these birds have shown up at Whitefish Point in previous years too. One wonders which pet store they come from, who is releasing these birds, and if they will ever establish feral populations.