Spring 2012 Migration Report

A mild winter allowed for an early start date of 20
February for the 2012 season. Three of the last ten days
of the month had winds with a southerly component.
New early dates for the site were set for Bald and Golden
Eagles, and the 1981 early date of 22 February for
Turkey Vulture was tied in 2012. In all, 138 migrating
raptors of 8 species were tallied in 25 hours over five
days of counting.

It was commented (or lamented) by many a regular
that we really need boom/bust cycles in the weather
to induce good hawk flights: a couple of days of poor
weather backing birds up followed by a single day of
south winds ahead of a powerful front will make for a
big push of birds. Such things never occurred in March
or April of 2012. An incredible 20 days in March saw
at least some winds with a southerly component, with
an unprecedented 24 days seeing part or all of the
count being conducted from the north lookout. Despite
these statistics, the counts for the month were overall
relatively light, with Red-shouldereds, Red-taileds, and
Rough-leggeds in particular being missed.

The month did, nonetheless, have its highlights. The
second produced 19 Eagles, 11 of them Goldens, all
amidst 213 other raptors. The day also saw about 4,000
migrating crows, and an impressive flight of over 92,300
Snow Geese. Flights for the first half of the month never
topped 300 raptors, but non raptor highlights continued
including a single Ross’s Goose picked out of about
22,400 Snow Geese on 9 March, and flights of Bohemian
Waxwings occurred on five days from 11 to 17 March.

The seventeenth produced the first four digit raptor
flight, including the season high counts for Red-tailed
and Cooper’s Hawks of 377 and 43 respectively, both
extremely light numbers relative to historical data.
Vulture numbers continued to ramp up while the counters
continued to wonder where all the Buteos were. The
flight of 26 March was well worth noting, with a James
Bay High sinking in and temperatures failing to make it
above zero Celsius. North winds gusted to 45 mph, all
making for the kind of day a counter should take off,
but the birds had other ideas. The north winds hitting
the drumlins lining the lakeshore apparently created just
enough updraft to keep hormone driven, sideways flying
birds on the move and nice and low. A visitor wonderfully,
if not a touch bit anthropomorphically, summed up the
day’s movement in saying “these Vultures must have one
h*** of a sweetheart to get home to if they’re moving in
this kind of weather”. In all 690 Vultures were tallied for
the day along with 34 Accipiters of all three species, and
while only 5 Red-tailed Hawks were counted, one was
a jaw droopingly gorgeous Harlan’s type bird, seen only
from above but showing off an impressive blue and
silver marbled tail. Two days later, 28 March,saw a more
traditionally good weather pattern developing, with a low
just a few hundred miles to the west northwest, and winds
starting out of the southeast and shifting to westerly origins by
day’s end. The weather made for a truly click-a-licious late
March mega flight with 3027 birds tallied including
a 20 minute span with over 950 birds passing. Included in the
day’s numbers was a new single day record for Turkey Vultures
at the site: 2731. Non raptors were on the move this day too,
with over 3000 Robins noted, 20 Great Blue Herons, and an
impressive 93 Common Loons headed north.

The month ended with sightings of two species not
overly uncommon but surely of interest to any raptor
biologist: a Saw-whet Owl and a Northern Shrike. In
total, March was covered for 178 hours on 29 days, with
10,896 raptors of 15 species counted as migrants.

While the first day of April was a rainout, the 2nd
through 4th produced some noteworthy flights from the
south lookout on off winds from the west and northwest.
The three days saw 3812 migrating raptors of 15
species, including two Black Vultures and the season’s
first Swainson’s Hawk and a dark Red-tail’ on 2 April
and a Krider’s type ‘Tail 4 April. Two Sandhill Cranes,
one each on the 2nd and the 4th, were also noted. Of
course the bulk of the flight was still Turkey Vultures,
accounting for all but 448 of those 3812 raptors.
Winds continued to be predominantly north and
northwesterly in origins through the 13th of the month.

While the first Broad-winged Hawk did show up on the
earlier side of average on 8 April and an additional dark
Red-tail’ was noted on 13 April, the 9 day period from 5
to 13 April never saw a count of more than 400 raptors.
The only non-raptor worth mentioning in this period
was a putative second cycle Lesser Black-backed Gull
on the 9th. The counter could often be heard humming
that old Disney tune “someday my winds will come”,
and on the morning of 14 April, the winds finally had
a southwesterly origin, though they became light and
variable as the day progressed. Nonetheless, 14 April did
see the season’s first triple digit counts of Sharp-shinned
and Broad-winged Hawks, in addition to season high
counts for Sandhill Crane (3), Northern Flicker (221), an
estimated 700 Rusty Blackbirds, and the season’s only
Red-throated Loon.

16 April finally saw some decent south winds and
temperatures making it up to an unseasonably warm 30
Celsius. The accompanying flight got painfully high,
with two individuals taking turns in the proverbial
official counter hat. By the end of the day, 3431 raptors
had been counted as migrants, including 2003 Broadwinged
Hawks and 629 Sharp-shinned Hawks. No one,
however, was prepared to go home that night to read
of Braddock Bay’s count of 37,145 raptors, including
34,243 early Broad-winged Hawks, 47 Bald Eagles,
and 1611 Sharp-shined Hawks. The birds we missed at
Derby all presumably cut the southeast corner of Lake

Weather and birds returned to disappointing levels
for the next nine days, with the 21st and 22nd seeing
only one migratory raptor in 6.5 hours of counting, and
no count was conducted on the 23rd. The 24th, while
only producing 74 raptors, did see the season’s second
highest count of Common Loons with 39 tallied, and nine
species of Sparrow on the property, including the
first of four (for the season) Grasshopper Sparrows. Also
of note this date was a pair of Lapland Longspurs seen
along Sage Creek Drive (not on the property proper but
close enough to include in the report).

26 April finally saw a decent weather system in the area,
with a low just to the north moving east and winds of
southerly origins, though the low was a bit close for that
wedge of warm air between a warm and cold front so
valued in a truly classic weather pattern. Nonetheless,
2706 raptors were tallied on an extremely spread out
flight with birds zigging and zagging out over the
water and then way inland, giving the counter quite the
headache to keep track of them all. On the back side
of the low were blustery northwest winds and even
some snow on 27 April, with light northwest winds and
continued chilly temperatures (from 2 to 6 Celsius) on
28 April. Hormone driven birds were, however, ready to
fly on the 28th, with 2220 raptors counted, all but 201 of
them Broad-winged Hawks. The final day of the month
saw improved weather with a bit of southeast wind in
the morning, but no spectacular flight to accompany it.
In total, April was covered for 176 hours on 27 days
with 17,658 raptors of 17 species counted as migrants.

If March and April were a touch bit of a disappointment,
May more than made up for it! In fact, 2012 saw the
highest May count in the history of Derby Hill, with the
22,337 birds tallied as migrants more than besting the
previous record for the month of 18,279 from 1982.
2 May saw temperatures working their way up to 24c,
but amazingly, a temperature differential enhanced lake
breeze never developed; the winds stayed light south
southeast all day, with a high flight that included the
season high counts for Osprey (137), Sharpie (664),
Harrier (33), and the second highest single day Bald
Eagle count (39). 3 May looked to be a repeat of the
amazing weather, but instead found the site socked in by
fog for much of the day. The count had been given up on
at two, with only four hours of coverage and 115 birds
counted. The weather and birds had other plans however,
with the fog finally lifting at about 2:15, and the birds
started coming through by the thousands! 1822 birds
were tallied between 2:30 and 3:00, and an impressive
6827 birds were counted from 3 to 4, the official counter
doing everything he could to keep up with the flight,
and David Wheeler on the proverbial side lines doing
everything he could to keep the counter semi sane,
focused, and missing as little as might be possible. 4
May saw three counters taking various parts of the day’s
count and 4030 birds tallied, the overall volume lighter
than the previous day’s but a second ever in the history
of Derby Hill Swallow-tailed Kite documented more
than making for an exciting day to say the least. The first
week of May ended with lighter counts of raptors, but
6 May did see a Pacific Loon fly by the south lookout
which, pending NYSARC’s deliberations, should be the
first officially accepted record of the species for Oswego
County. Finally, 7 May saw the peak Blue Jay count for
the season with 2600 estimated to have flown by.

Non raptors continued to abound and impress through the
middle of May. 111 species of ornithid were documented
at the site by just two observers on 9 May, including 20
species of Warbler, 10 species of Sparrow, and the 11th
Sandhill Crane to pass the site for the season (which
would also prove to be the last of the season). Some 23
species of Warbler were documented in a two hour early
a.m. hike about the hedgerows on 12 May including
Prothonotary, Worm-eating, and Orange-crowned. A
flight of about 1200 Brant in three loose flocks were a
nice avian highlight to the early afternoon of 15 May.

After the first week of May, the hawk flight tapered off
as expected. Disappointingly, a single day predominantly
juvenile Broad-winged flight of more than 606 birds never
occurred. “Florida” Bald Eagles, however, continued to
impress right through the end of the month, with six dates
in the last two weeks of May seeing counts of fifteen or
more individuals of the increasingly common big bird.
The peak flight for the species came on 28 May with
44 counted on moderate south and southwest winds as
temperatures climbed to 30C.

In total, May was covered for 174 hours over 30 days,
with 22,337 individuals of 17 species of raptor counted
as migrants.

Black Vulture
The smaller of North America’s two vultures broke all
kinds of records at Derby Hill in 2012. Two individuals
seen on 15 March marked a new early date for the
species, and by the end of the season, a record high
count of six were recorded as migrants with a seventh
west bound bird noted but not counted under our
standardized protocol. The data scientifically support
what many northeastern birders can tell you anecdotally:
sightings of this species have become more frequent at
more northern latitudes in recent years.

Turkey Vulture
How can there be this much road kill in the northeast? That
is one of many questions left to ponder after another record
breaking year for Turkey Vultures. The 15,032 tallied
shatters the 2009 previous season record flight of 13,250,
and the impressive flight of 2731 individuals (including a
single hour with 1215 birds clicked) on 28 March marks a
new single day record, besting the previous record flight,
also from 2009, by 60 individuals. An additional two days
in 2012 saw quadruple digit Turkey Vulture flights: 1314
on 2 April and 1246 on 4 April.

The 556 Ospreys tallied as migrants in 2012 figures to
be above both the historical average and the average
for the last decade (427 and 396 respectively). Much of
this above average flight can be attributed to the 2 May
flight of 137 birds. While far off the record single day
flight for the site of 201 individuals back in 1990, the 2
May 2012 flight is the tenth best in Derby Hill history,
and only the twelfth single day that three digits worth of
Ospreys have been tallied.

Swallow-tailed Kite
One of many season highlights for 2012 was the passage
of a Swallow-tailed Kite at 12:21 directly over the Don
Barnes South Lookout on 4 May. This marks the second
Swallow-tailed Kite seen at Derby Hill, the first on 16
April 1976. 2012’s Swallow-tail’ was likely the same
bird seen two days earlier at the Hamburg Hawkwatch
on the southeast shore of Lake Erie, just south of Buffalo.

Bald Eagle
539 Bald Eagles were tallied as migrants at Derby
Hill in 2012, only the second year ever with over 400
individuals counted and only 70 birds shy of the all time
high count from 2011. The first single day double digit
count of Bald Eagles did not come until 14 April, and 14
of the season’s 17 double digit days came in the month
of May, with that last month of counting seeing 381
of the year’s Bald Eagles. 136 of 2012’s Bald Eagles
were identified as adult birds, while 345 were non
adults and 58 birds went by unaged. Of the non adult
birds, barely more than a third were assigned a more
specific age class, with only 68 being summer 2011 or
winter 2011/2012 hatched while an astonishingly high
47 individuals were thought to have been hatched in
summer 2010 or winter 2010/2011. Ten were thought
to be hatched in summer 2009 or winter 2009/2010,
with another six thought to be hatched summer 2008 or
winter 2008/2009. Also interesting to note is the month
by month ratio of adults to non adults. Both February
and March saw equal numbers of adults and non adults
(7:7 and 23:23 respectively), April saw about two non
adults for every adult (51:26) and May saw about 3.3
non adults for every adult (264:80).

Northern Harrier
The 365 Harriers counted in 2012 marks the second
lowest count for the species in the 34 years of
standardized monitoring at Derby Hill. While a
downward trend is barely detectable over the 34 years,
it is a bit discouraging to note that in the last decade,
only one season’s count has been higher than the 33
year average for the species at the site of 664. On the
other hand, that average is undoubtedly skewed by a few
high outlier counts, including of course the 1995 double
counter year total of 1554. Harrier numbers at Derby
Hill are some of the most variable of our 15 regular
species, with winter snow cover largely dictating how
far south the birds need to travel, and as an added layer
of variability, the smaller males being more effected
by the snow than larger females. The largely snowless
winter of 2011/2012 would, therefore, dictate a low
Harrier count in spring 2012, and perhaps can put the
conservationists among us a bit more at ease with the
light count.

Also boding well for the species is the incredibly high
43.3% of the 157 aged birds being young of last year,
indicating a good reproductive season in 2011 and/or
a good overwinter survivorship for the 2011 hatched
cohort. Of course, the number only seems high in and
of itself, and we have only 2009 data readily available
to compare this percentage with. 2009 was another light
Harrier year, now the fourth lightest in 34 years, and
24% of individuals that season were noted to be less
than a year old. With a species with numbers as variable
as those of the Harrier, I cannot stress enough to future
hawkcounters and management the value of collecting
data on age and sex structure to help better understand
migration ecology and ultimately create a meaningful
population index. Also of note for the 2012 season are
the mean dates of passage for the various age and sex
classes of the species, perhaps adhering as closely to
conventional wisdom as any I’ve seen in six seasons of
hawkcounting. Adult males had a mean date of passage
of 27 March, while adult females had a mean date of
passage of 7 April and immatures had a mean date of
passage of 16 April, with 21 of 25 aged birds in May
being the young of last year.

Sharp-shinned Hawk
The 2012 Sharp-shinned Hawk count of 3833 is above
the average for the species at the site over the last decade
of 2864 while remaining below the historical average of
4653. A good bit of data mining and comprehension of
larger factors at play (from spruce budworm outbreaks to
an assessment of the theory of migratory short stopping)
are needed to make sense of northeastern populations
of Sharp-shinned Hawks. Biologists with the Raptor
Population Index and Hawk Migration Association
of North America are currently working towards a
meaningful assessment of the health of the populations
of North America’s smallest Accipiter with Derby
numbers and data from other indices. At Derby Hill in
2012, the peak Sharp-shinned Hawk flight came on 2
May with 664 birds tallied, while the second highest
daily count had come over two weeks earlier on 16 April
with 629 birds tallied. All together, 9 dates from 14 April
to 7 May saw counts of over 100 Sharpies.

Cooper’s Hawk
The 361 Cooper’s Hawks counted in 2012 is quite the
recovery from the 2010 and 2011 all time low counts for
the species, and is just above the average for the species
at the site for the last ten years of 341, while being well
below the 33 year average of 462. Of 133 aged birds,
about 82% were adults. The peak flight came on 17
March with 43 individuals tallied; the second highest
single day count for the season was 32 Coops tallied on
two mid April days, the 14th and 16th, surely on the later
side of average for the species at this site.

Northern Goshawk
The cyclic nature of the population numbers and
movements of Goshawks continued to disappoint at
Derby Hill and throughout the northeast for the spring of
2012, with the season total of 15 marking the third lowest
count for the species in the 34 years of standardized
counting. Of those 15 birds, only three were identified as
adult types, with a fourth individual having undergone
just one incomplete prebasic molt, in other words, likely
hatched in 2010.

Red-shouldered Hawk
The 388 Red-shouldered Hawks tallied at Derby Hill in
2012 marks a slight uptick form the 2010 and 2011 all
time low counts, but still figures to be not only the fourth
lowest count for the species on the books, but also one
of only four counts for the species below 500 birds. 280
individuals were aged in 2012, with an astonishingly
high 35% being last year’s hatched birds. As usual, the
last documented adult passed on 2 April, but unusual was
the early passage of so many young birds, with flights as
early as 17 March being composed of upwards of 1/3
and 1/2 immature birds. While these numbers bode well
for a decent reproductive year in 2011 and a high winter
survival of that cohort, the higher proportion of surviving
2011 birds may mask the continued downward plummet
of the portion of the population of the species passing
Derby Hill each spring. In other words, my guess is that
an analysis of just adult numbers (if such data existed)
would show 2012 to be the lightest ‘Shoulder year in the
history of Derby Hill.

Broad-winged Hawk
It was feared through the end of April that 2012 would be
the third year in 34 that Turkey Vultures bested Broadwingeds
as the number one raptor for the count. While
the first of the little long distance migrants showed up a
bit early on 8 April, April never saw a single day count
of over 2297 of the little Buteos, but then came May.
An incredible 14400 Broad-wingeds passed in the three
days from 2 to 4 May, including three different hours
on 3 and 4 May with over 1500 birds per hour. The end
of season total of 25,807 for the species figures to be
the sixth highest in 34 years of standardized monitoring,
and more interestingly is the first time since 1985 the
count has topped 24,000 individuals.

Red-tailed Hawk
The 3418 Red-tails tallied in 2012 figures to be the second
lightest count for this species in the history of Derby Hill,
and is one of only four years were the count fell shy of
4,000 birds, the other years being 2007, 2010, and 2011.
Much of this year’s poor count can be attributed to the
mild winter, with many individuals likely not traveling
as far south in the fall, and therefore not needing to pass
Derb on their way north in the spring. Indeed, many
fall sites across the east coast saw light ‘tail counts in
2011. Still, the recent flurry of light counts does raise
the proverbial eyebrow of the conservationists among
us, with a steady downward trend detectable starting
in about 1996. An exponential line of best fit for this
period indicates a decrease of about 3.5% per year, with
an R-square value of about 0.47.

While the sheer numbers of ‘tails in 2012 did disappoint,
there were a number of notable individuals. Most
interesting was a Harlan’s type bird seen from the north
lookout on 26 March. Four dark and one dark or rufous
morph birds were seen: one on 13 March, two on 27
March, one on 2 April, and one on 13 April. Two Krider’s
types were seen, one each on 4 and 19 April. Additionally,
upwards of a dozen light morph birds were observed to
have traditionally calurus like traits, most of these
passing in the last week of March and first half of
April. Whether these birdswere (1) genuinely of the
B.j. calurus subspecies, (2) B.j. borealis birds
showing more variation than books will give
them credit for, or (3) individuals belonging to
the illusive if not entirely hypothetical B.j. abeiticola,
we will never know. Some 2022 Red-taileds were aged
in 2012, with only 15% ofthose being young of last year.

Swainson’s Hawk
Three of these handsome, long winged, long distance
migrants were seen at Derby Hill in 2012. The first was
likely over the north lookout, though it was seen from
the south lookout amidst the spread out flight on 2 April,
and the other two (on 2 May and 9 May) were out over
the Lake, seen from the north lookout, and not identified
until they were “behind” us, or to the northeast. Suffice
to say, none were overly amazing looks, and only the
second bird was aged as last year’s model. Nonetheless,
in addition to being one of this counter’s favorite
raptors, the three are significant in being the first time in
Derby history that more than two have been tallied in a
single spring.

Rough-legged Hawk

The 123 Rough-legged Hawks counted as migrants makes for the second
lightest Rough-leg year in Derby Hill’s history. It is furthermore
only the fourth time the count for the species has fallen shy of 200
birds, and is well below the 33 year average of 345. This species
likely suffered as much as any from the abnormally warm winter, with
the lack of snow to the north not encouraging this non facultative
migrant to head south in fall, and back past Derb in the spring. As
such, the low number does not indicate a population crash or decline
of any type.

Much additional data was collected on the age and sex of Rough-legs
passing Derby Hill in 2012. 2012 saw an abnormally high percentage of
adult male birds, with 35 noted to have passed the site while only 10
adult females were identified and only 9 birds were tallied as the
young of last summer. It is also interesting to note that while the
later average date of passage of immatures of 10 April is to be
expected, the virtually identical average dates of passage for adult
male and adult female types of 14 March and 13 March respectively are
not what conventional wisdom would coin as normal; most books would
have one believe the males move before the females in the spring to
stake out territories.

Percentages of dark and light birds were about in line with those
deemed normal by former counter John vanDort in his 2008 article on
Rough-legged Hawk Migration at Derby Hill, published in HMANA’s Hawk
Migration Studies. A color morph was documented for 99 of 2012’s
Rough-legs, with 72 being light and 27 being dark.

Golden Eagle
The 72 Golden Eagles tallied in 2012 figures to be
the fifth highest count for the species at Derb behind
2011, 2000, 2008 and 2003. Migration of this species
by Derby Hill is moderately weather dependent, with
the big birds easily staying on the ridges to our south
and east in their northward movements when a strong
south wind is not blowing. Further complicating the
matter is the extreme differential migration exhibited by
the varying age classes in the species. Nonetheless, the
general population trendline for Golden Eagles passing
Derby Hill seems to be in the upward direction.

In 2012, only 7 Golden Eagles were identified as
definitive plumaged adults, with 6 of those birds passing
on 2 March and the 7th on 17 March. 16 birds were
identified as the young of last year, with a mean date
of passage for those birds of 16 April. Another 26 birds
were identified as non adults of sorts with the remaining
23 individuals being unaged.

American Kestrel
The 2012 Kestrel count of 200 falls below both the
previous ten year and the historical 33 year averages for
the species of 256 and 397 respectively. I do not know
how many end of season reports I have written for how
many sites where I drone on about declining Kestrel
numbers, and surely regular readers are familiar with
the facts from previous Derby Hill Newsletters. While
Peregrine Falcon and Bald Eagle numbers from Derb
are evidence of the success of the Endangered Species
Act and the ban on DDT in the United States, Kestrel
numbers are indicators to us that not all is well with the
natural world and some of the organisms we share this
planet with.

The 42 Merlins tallied at Derby Hill in 2012 are above
both the previous ten year and historicalaverages of 34
and 26. Those familiar with Derby Hill as a hawkwatch know
the site is not ideally situated to monitor the populations
of Merlins orPeregrines, but the above average number is
nice nonetheless for any visitors and regulars who got a brief
glimpse of one of the little raptors with a lot of attitude.

Peregrine Falcon
Peregrine Falcons had a record tying year in 2012, with
the 21 recorded matching the previous all time high
count from 2008. Despite the relatively light percentage
of the northeastern population that we see at Derby Hill
each year, our numbers still indicate and upward trend
(a basic transformation yields a growth rate of about
5.2%per year with a moderate R-square value of 0.366),
validating the species’ status as an Endangered Species
Act poster child.

Report prepared by Kyle Wright