2019 Fall Season In Review

Compiled by Jeff Bouton and Rafael Gálvez

The Florida Keys Hawkwatch 2019 fall count season was conducted from September 7 through October 31, 2019. The season’s start was delayed a week by Hurricane Dorian, a powerful Category 5 storm that raged along the Atlantic. Florida’s governor declared a state of emergency on August 28 resulting in the closing of facilities associated with the project, including state parks and housing.

Official counters for 2019 were Luis Gles, Karl Bardon and Felipe Anaya Osorio.

The 2019 hawk count season in the Florida Keys, which operated from September 7th – October 31st was notable for being our 20th year of operation. However, the fall 2019 weather was unusual in that it was almost devoid of cold fronts with N to NW winds, which have historically proven to be the most conducive for promoting large hawk flights over the Florida Keys. The bulk of the 2019 count days were plagued by comparatively unproductive easterly winds leading to lower detections and below average counts overall. The chart below lists daily wind directions. To summarize, favorable N to NW winds were only recorded on 3 of 55 (5%) count days and easterly on 43 of 55 (78%) days.

2019 Migratory Raptor Count – FKH at Curry Hammock State Park

2019 Winds:
East – 25 of 55 count days (45%),
NE – 12 days (22%)
SE – 6 days (11%)
S – 4 days (7%)
SW – 3 days (5%)
W – 2 days (4%)
N – 2 days (4%)
NW – 1 day of 55 count days (2%).

The fall 2019 total count was only 13,781 raptors, which is the lowest full season total we have recorded since the 2010 count of 10,227 raptors. Likely not coincidentally, the winds in 2010 were easterly on 81% of the count days. Despite poor winds reducing overall raptor numbers over the middle keys, there were individual daily highlights throughout, which will be covered in the species accounts below.

Vultures
Black Vulture (Coragyps atratus)           HMANA Code: BV

Average: 2
Max: 4 (2019)
Min: 1 (2018)

Turkey Vulture (Cathartes aura)             HMANA Code: TV

Average: 3,908
Max: 11,475 (2000)
Min: 994 (2019)
Notable: 5714 (Oct 30,2012)
3833 (Oct 26,2014)
2632 (Oct 28,2000)

Even though we recorded a new high daily and seasonal count of 4 Black Vultures on October 11, 2019, the number is of marginal significance given the comparatively small sample size. The continuing scarcity of BV over the mid to lower keys reinforces what we have noted in past seasons, that Black Vultures prefer to stay on the mainland of the Florida peninsula rather than migrate down onto the Florida Keys, presumably due to their hesitance to cross open water.

FKH historic data shows the peak of the Turkey Vulture migration occurs from the last week in October through the first two weeks in November. So much of the seasonal fluctuation here is relative to whether or not we have favorable conditions in late October before wrapping up the season.

The 2019 tally of 994 Turkey Vultures falls well below the seasonal average count of 3,908 (only 25.4%). However, that average is slightly skewed by the fact that some past seasons have continued into November. As expected, TV flights picked up in late October with seasonal high days of 153 and 226 tallied on October 27th and 28th respectively on east winds. Anecdotally, the winds did turn north on November 2nd and 3rd, 2019 and recreational birders shared reports of large Turkey Vulture and buteo flights over the middle and lower keys. These included a single kettle of 104 Turkey Vultures over Blue Hole on Big Pine Key on the evening of November 2nd 2019; and then multiple large kettles streaming west while driving north toward the mainland on November 3, 2019: >150 TV over Marathon at 11:50 a.m. in a single kettle (with stragglers streaming behind to ~175 TV) with 15 Swainson’s Hawks and 3 Short-tailed Hawks in the same flock; and an additional 137 from Long Key State Park near 12:44 p.m. with more SW and ST Hawks as well. In short it seems the largest TV flights came just after our season wrapped up in 2019 and the count would have certainly been much higher if the watch had been manned on those days.

Ospreys, Eagles, & Harriers
Osprey (Pandion haliaetus)                     HMANA Code: OS

Average: 1424
Max: 3635 (2014)
Min: 453 (2010)
Notable: 394 (Sep 25,2014)
340 (Oct 01,2003)
316 (Oct 01,2014)

Bald Eagle (Haliaeetus leucocephalus)    HMANA Code: BE

Average: 19
Max: 46 (2015)
Min: 4 (2019)
Notable: 8 (Oct 30,2015)
8 (Oct 06,2015)
6 (Oct 02,2010)

Northern Harrier (Circus hudsonius)       HMANA Code: NH

Average: 635
Max: 1063 (2011)
Min: 332 (2009)
Notable 238 (Oct 20,2011)
150 (Oct 18,1999)
139 (Oct 20,2012)

Osprey numbers in 2019 were well above the seasonal average with 2,250 individuals counted (3rd highest season count behind 2014 and 2018 respectively). It is assumed that this fish-eating species will follow the coastal path, so may be less affected by adverse winds than other soaring species not necessarily tied to the coast. The peak daily count of 220 individuals occurred on September 22, which was also the highest total raptor count for September as well as our 2nd highest all-time count for Merlins! The winds were NE on this day, but they were strong and consistent, unlike many other days which were light and variable.

Bald Eagle numbers were at an all-time low with only 4 individuals tallied. BE were observed far more often but these were considered to be part of a local resident population that nested just north of the count site. Both OS and BE are difficult to count accurately given that the resident populations can mix with migrant birds, but this challenge is consistent from year to year.

The Northern Harrier count tally was also well below seasonal averages with 455 tallied in fall 2019 and peak days falling at 46 individuals or less. It is safe to assume that this species tally was absolutely affected by the winds in 2019. NH flights peak in the third week in October but remain strong through the first week in November so it is possible that good flights were missed during the strong northerly winds on November 2-3.

Kites
Mississippi Kite (Ictinia mississippiensis)     HMANA Code: MK

Average: 57
Max: 128 (2014)
Min: 6 (2006)
Notable: 28 (Sep 27,2012)
23 (Sep 16,2001)
21 (Sep 15,2019)

Swallow-tailed Kite (Elanoides forficatus)   HMANA Code: SK

Average: 53
Max: 256 (2014)
Min: 3 (2000)
Notable: 65 (Sep 04,2014)
50 (Sep 09,2018)
47 (Sep 03,2014)

Snail Kite (Rostrhamus sociabilis)                HMANA Code: SN

Average: 2
Max: 4 (2018)
Min: 1 (2016)
Notable: 2 (Oct 21,2018)
1 (Sep 28,2007)
1 (Oct 10,2019)

White-tailed Kite (Elanus leucurus)              HMANA Code: WK

Average: 1
Max: 1 (2014)
Min: 1 (2014)
Notable: 1 (Oct 17,2014)

In 2019 we once again tallied three species of Kites from the hawkwatch. Mississippi Kite numbers were well above the average seasonal total with 94 individuals tallied and single day counts of 21 individuals tallied September 15th (third highest single day flight) and 14 more on September 16th on SW and W winds respectively. Our historic data shows that the peak of detections of MK occurs from mid-September through the first week in October so this is right at the beginning of this peak season.

Swallow-tailed Kites were above the seasonal average with 89 individuals tallied from the hawkwatch platform in 2019, but still a long way from the record flights. This is related to seasonality and start up dates. We know from our historic data that the biggest daily flights in FKH history have all occurred in the first 9 days of September and graphing our data shows that SK are already at peak abundance by the September 1 start up. Since our count started September 7, 2019 – delayed by Hurricane Dorian along the Atlantic – we missed our historic peak window that falls during our typical count range.

The reality is that the bulk of SK migrate before the count even begins. We know that SK stage in preparation for migration in July and numbers at these communal roosts drop through August. We are not manning the watch early enough to capture the peak of this migration.

The graph above is courtesy of eBird.org and shows sightings for SK in Monroe county with highest daily counts in late July and August (exceed record days from FKH by almost 500%). SK are rarely detected in the Florda Keys in June, with only 4 individuals being reported during that month to eBird in the past decade. However, that changes dramatically in July.

The following eBird report by Andy Kratter of the Florida Museum of Natural History, is from Grassy Key less then 2 miles NE of Curry Hammock on July 25, 2019 – https://ebird.org/checklist/S58450273. Between 2:20 p.m. and 2:35 p.m. he counted 136 Swallow-tailed Kites, including a single kettle of 120 birds. The single photo included shows 61 individual birds at once (FKH record day is only 65). Similarly, an eBird report from Bryan White from Long Key State Park reports 150 SK passing in 2 southbound groups on midday of August 25, 2019 – https://ebird.org/checklist/S59253926.

Unfortunately, the data FKH captures on Swallow-tailed Kite migration represents just the very tail end of SK migration. These two single reports document 286 migrant SK in a mere 25 minutes of observation a full month apart. Increasing valuable Swallow-tailed Kite monitoring is a long term goal of the Florida Keys Hawkwatch, but this would likely be treated as an additional count effort overlapping with the regular count. The biggest challenges to this goal are the fiscal considerations of additional labor as well as the prohibitive costs of housing in the keys. Adding a Swallow-tailed Kite satellite monitoring project would require a minimum of $5,000 to cover expenses alone, the bulk of course going just toward housing.

On October 10, 2019, a single juvenile Snail Kite was seen and photographed passing directly over the hawkwatch shortly after 3 p.m. in a mixed kettle (photo courtesy Jeff Bouton). These sightings, while still unusual, are becoming a near-annual occurrence over the past few years. The bird streamed right through that afternoon disappearing to the south and was not seen returning by the time the watch ended for the day at 6 pm. Interestingly, this bird or another juvenile was observed hunting the following morning at Long Key SP during the daily census.

No White-tailed Kites were seen in 2019. The sighting on October 17, 2014 remains the only record from the hawkwatch.

Accipiters
Sharp-shinned Hawk (Accipiter striatus)      HMANA Code: SS

Average: 2585
Max: 4741 (1999)
Min: 596 (2018)
Notable: 1525 (Oct 20,2011)
1472 (Oct 18,2008)
1241 (Oct 10,2015)

Cooper’s Hawk (Accipiter cooperii)              HMANA Code: CH

Average: 533
Max: 1036 (2004)
Min: 136 (2019)
Notable: 155 (Oct 19,2008)
152 (Sep 28,2007)
127 (Oct 22,2011)

While the 2019 Sharp-shinned Hawk count of 1,473 was well below the season average of 2,585 it was not as bad as other recent years, more than twice the 2018 all time low, and ~40% higher than 2016 (2017 cancelled following park closures after Hurricane Irma). Given the small size of these birds they are likely affected heavily by wind direction. It is difficult to assess what effect easterly winds might have had on the detection of these flights. As the smallest of the raptors passing by, detection is another real difficulty. Days with very light winds and high thermal activity can provide enormous lift making these small birds extremely difficult to detect in clear blue skies. We have even witnessed birds soaring so high that they literally disappear into a lower ceiling of clouds.

However, Cooper’s Hawks are another story entirely. The 2019 count of only 136 CH is not only well below average but is by far, the lowest full season count ever recorded at FKH. The next lowest tally was 237 in 2010 and then 371 in 2018. Other recent flights have exceeded 800 individuals. We are at a loss to explain this anomaly and can only assume this is an effect of the odd winds. We will be very curious to monitor the 2020 Cooper’s Hawk flights. As the chart demonstrates, the entire CH 2020 total is lower than two of our record daily counts for the species and barely higher than the third highest daily count!

Buteos
Broad-winged Hawk (Buteo platypterus)    HMANA Code: BW

Average: 3968
Max: 7236 (2012)
Min: 1538 (2015)
Notable: 1398 (Oct 30,2012)
1363 (Oct 10,2011)
1255 (Oct 16,2010)

Red-shouldered Hawk (Buteo lineatus)       HMANA Code: RS
Average: 22
Max: 72 (2011)
Min: 1 (2002)
Notable: 17 (Oct 22,2011)
13 (Oct 23,2016)
11 (Oct 25,2011)

Short-tailed Hawk (Buteo brachyurus)        HMANA Code: ST
Average: 33
Max: 65 (2015)
Min: 15 (2003)
Notable: 17 (Oct 30,2015)
11 (Oct 31,2015)
11 (Oct 21,2018)

Swainson’s Hawk (Buteo swainsoni)            HMANA Code: SW
Average: 66
Max: 156 (2011)
Min: 4 (2016)
Notable: 56 (Oct 30,2012)
50 (Oct 30,2015)
41 (Oct 31,2015)

Red-tailed Hawk (Buteo jamaicensis)          HMANA Code: RT
Average: 2
Max: 5 (2001)
Min: 0 (2019)
Notable: 3 (Nov 11,2001)
2 (Oct 25,2011)
1 (Sep 28,2011)

Buteos are broad-winged soaring hawks that are very dependent on thermals and uplifts during migration, avoiding powered, flapping flight as much as possible. They are a diverse group with varied diets and with very different wing structure between species, but as a whole they are less apt to undertake long water crossings compared to other species groups. This has made these birds difficult to count in the Keys – much like vultures – as they are more prone to linger or backtrack. We have maintained consistent count methodology though insuring variables are limited so long-term data should still provide useful population trending.

The most abundant migrant buteo species across the Eastern U.S. is easily the Broad-winged Hawk, typically appearing in large “kettles” often reaching hundreds and sometimes thousands of individuals, particularly on inland ridge sites. Coastal sites throughout the east tend to see fewer, and the bulk of the Broad-wingeds migrate West of the Gulf of Mexico and down the Mexican mainland in fall. In 2019 FKH recorded a respectable 2,787 Broad-wingeds in migration. Still lower than the seasonal average but not our lowest year by any means. Our peak days were back to back flights on October 9th and 10th with 574 and 530 BW tallied respectively. These were the best two count days of the season as well at

1,627 and 1,499 raptors tallied respectively (>22% of total raptor detections, 40% of total BW on two days).

Unlike BW that winter to Northern Bolivia in central South America, Red-shouldered Hawks only winter as far south as the Florida Keys and not beyond. Most stay on the mainland though, so these are recorded in lower densities at FKH, and 2019 was a fairly typical season with 15 RS tallied. However, the bulk of the migratory Northern subspecies, nominate Buteo lineatus lineatus, is known to migrate very late in the season with peak flights in the NE occurring late October into November so it is possible we would tally more if we extended our season into November.

Short-tailed Hawks are a tropical raptor only reaching the US in number in Florida, so FKH is the only U.S.-based hawk watch site that has a migratory flight of ST to monitor. Very little is known about the movements of these raptors in the state, with limited data from FKH over the years and some telemetry studies conducted by Ken Meyer and the Avian Research & Conservation Institute (ARCI) http://arcinst.org/arci-tracking-studies. This research seems to suggest that Short-taileds are somewhat sedentary and do not wander far. However, our sightings and other anecdotal detections seem to suggest we do not fully understand their movements and need to invest more time and effort to understand why so many of these birds come to the Keys. As with other buteos including Swainson’s Hawks, this species’ numbers build through late October and presumably continues well into November.

You can see from the FKH migration data that two of our peak daily flights have occurred just as we are typically wrapping up our season on October 30 and 31. We have continued into November on a handful of seasons but even with this limited data collection we note that the peak detections for this species continue at least through the first week in November.

Swainson’s Hawks are another unique species with a mysterious distribution. Primarily a breeder through midwestern plain states and Canadian prairies, very few SH are tallied on other eastern hawkwatch sites. Here in Florida however, we have small localized wintering populations and FKH typically tallies dozens of this Western raptor species each year. No one fully understands how these raptors get here, nor what route they take. In 2019 FKH counted 59 Swainson’s Hawks, which is only slightly below the season average.

You can see that like Short-tailed Hawks, Swainson’s migration peaks late, with best flights all being tallied on the final days of our current season (Oct 30 and 31), and that these flights carry on well into November. The high season count from 2011 was (not coincidentally) one of the few seasons when the hawk count continued until mid-November. Over these two weeks, 2,328 additional raptors were tallied including 1,200 Turkey Vultures, 17 Short-tailed hawks and 68 Swainson’s Hawks (more than our entire 2019 count of SW). Again anecdotally, strong Northerly winds blew in the Keys on November 2-3, 2019 and birders noted massive raptor flights while driving north toward mainland Florida on November 3rd, reporting many hundreds of Turkey Vultures and over 21 individual Swainson’s Hawks (15 in a single kettle over Marathon) and 9 Short-taileds. They noted that all of these birds were streaming south and the counts occurred were only when they noticed larger groups and pulled over to count, so the actual totals were likely notably higher. As a short term goal, we would like to extend the hawkwatch to mid-November to record these ornithologically significant Short-tailed and eastern Swainson’s Hawk flights. Again, expensive Keys housing has proven to be prohibitive with leases only running for full months.

Most Red-tailed Hawks winter north of the Florida Keys, so these are rarely seen and in 2019 we recorded none. Like Black Vultures, they are commonly seen on the mainland, but rare in the Keys.

Falcons

American Kestrel (Falco sparverius)    HMANA Code: AK

Average: 2337
Max: 4338 (2001)
Min: 1275 (2006)
Notable: 966 (Oct 01,2001)
648 (Oct 06,2000)
591 (Oct 16,1999)

Merlin (Falco columbarius)                 HMANA Code: ML

Average: 540
Max: 1042 (2018)
Min: 182 (2010)
Notable: 110 (Oct 14,2018)
102 (Sep 22,2019)
88 (Oct 07,2018)

Peregrine Falcon (Falco peregrinus)    HMANA Code: PG

Average: 2501
Max: 4559 (2015)
Min: 1344 (2010)
Notable: 1506 (Oct 10,2015)
651 (Oct 10,2012)
638 (Oct 11,2008)

Falcons (particularly Merlins and Peregrines) prefer to migrate coastally and largest counts have always come from coastal hawkwatch sites in the East like Cape May, NJ, Kiptopeke, VA and of course the Florida Keys Hawkwatch.

Despite lower than typical recent counts on many species, American Kestrels rebounded fairly nicely. While still below the 20-year seasonal average, the 2019 count of 2,121 Kestrels was a significant improvement over the low count from 2018 of only 1,489 AK and 2016’s 1,814. American Kestrel numbers have dropped significantly across the U.S. suspected as a result of changes in agricultural practices and fire policies resulting in less favorable grassland habitats. So seeing an upward trend is encouraging, maintaining the understanding that a single year’s count is not necessarily representative of population trending, but we can hope this is the beginning of a more positive trend for this species.

The 2019 Merlin count of 749 was well above the past season average count and is one of our highest

allies for this species, but still falls behind recent counts from 2018, 2016 and 2014. Unlike Kestrels, Merlin populations have been trending positively at coastal hawkwatches and they have recently expanded their breeding territories to the south, showing up for the first time as breeders in Ohio as example, with 2 nesting pairs found this year. This is good news for this aggressive little falcon species. As a 2019 highlight, the record high flight of 102 birds on September 22nd was the second highest daily flight on record and only our second count over the century mark!

Of course, the bird for which FKH is renowned is the Peregrine Falcon, earning FKH the nickname “Peregrine Falcon Capital of the World”. This not just hype, there is literally no spot on the entire globe where one can go to see more Peregrine Falcons (or even close) than in the Florida Keys; the world record for both seasonal, daily and even hourly flights has been set and rebroken here repeatedly over the past decade! The perfect mix of topography – the archipelago provides excellent hunting opportunities for this fast, bird-eating species as birds push toward South American wintering grounds. For young falcons still honing their hunting skills, spotting a small passerine (songbird) over water provides multiple opportunities for capture when the first attempts fail (over land the bird can simply plummet into the brush below for safety and it’s game over for the Peregrine). You can see this almost daily in October on coastal beaches and barrier islands up and down the east coast with hungry Peregrines perched on snags or driftwood looking out to sea expectantly.

In 2019 we tallied 2,517 PF, our lowest seasonal Peregrine total since 2010. However, there was a highlight with the 4th highest daily PF flight of 574 on October 9th and 530 more on October 10th (not coincidentally 2 of the only days with stronger northerly winds and our best two raptor tallies of the season). Of note, October 10th is the single date with the most Peregrine detections of any day in FKH history and our two, world record high flights occurred on October 10th on 2015 and 2012 respectively. For anyone wanting to see this Peregrine Falcon world class spectacle we always recommend picking a window of days on either side of October 10 to be guaranteed a massive flight. We’ve fondly referred to this day as “Peregrine Day” and “Dia de Los Peregrinos” but are realistically going to propose this as “International day of the Peregrine”. Of note, both of these peak flight days recorded at FKH exceeded Cape May’s entire season total for Peregrines (see below)!

While the winds may have affected the lower 2019 seasonal tally to a degree, there is clearly more going on here than just poor winds, as the two other prominent Peregrine Falcon hawkwatches in the Eastern US showed very dramatic declines from 2018 to 2019 as well.

Cape May, NJ = 1,521 PF in 2018; 480 in 2019 (68% decline)
Kiptopeke, VA = 1,375 PF in 2018; 646 in 2019 (53% decline)

This may be an indication that Peregrine Falcon populations in the Arctic had poor breeding success last summer, as one very plausible explanation for such a dramatic decline from one year to the next (FKH down 30%, Cape May down 68%, Kiptopeke down 53%). Poor breeding success due to eggshell thinning caused by DDT was the whole reason for the Peregrine Falcon (as well as Bald Eagle and Osprey) population crashes in the 30’s. It has taken enormous resources and much time to rebuild these populations to healthy levels, so this re-emphasizes the importance of consistent monitoring at sites like FKH, to sound-off warnings more rapidly when we see trends like this. If we see similar results in 2020 we will analyze our notes to compare percentages of adults to juveniles birds passing to see if we are noting the ratios of adults to juveniles changing dramatically as example.

The primary official counters during the fall of 2019 were Luis Gles and Karl Bardon, with assisting official counter Felipe Anaya Osorio. Additional assistance was provided by Rafael Galvez, Mark Hedden and Jeff Bouton. For hourly, daily and seasonal breakdowns of the 2019 season visit the HawkCount online repository, administered by the Hawk Migration Association of North America (HMANA). Link: https://www.hawkcount.org/month_summary.php?rsite=583.