Believe it or not, elevation plays a huge role in the type and occurrence of habitats in southern Florida and the Florida Keys. In the interior of South Florida, for example, the highest points are pine or oak dominated woodlands. Drop three or four feet in elevation, and you’ll be in a cypress dome or wet marl prairie (the latter being true Everglades). The mangrove forests that line the coast are yet another patent habitat associated with the region. Yet there is another important but lesser-known ecosystem in extreme South Florida and the Florida Keys that recalls more of a West Indian influence: tropical hardwood hammocks.
A hammock in this use of the word describes a dense hardwood stand of trees bordered by a wetland. And a tropical hardwood hammock, more specifically, is a forest comprised of tree species such as Gumbo Limbo, Poisonwood, Blolly, Wild Dilly, and Pigeon Plum, among others. In the Keys, it is often the habitat just inland from the mangroves of the coastline and estuaries.
If you visit Cuba, Hispaniola, The Bahamas, and even coastal Yucatan Peninsula, you’ll see that the flora of the tropical hardwood hammocks of extreme peninsular Florida and the Keys are more similar to the Caribbean than to the flora of other parts of temperate Florida. This is also apparent in the relationship between the bird species. For example, “specialties” of the Keys such as the White-crowned Pigeon, Mangrove Cuckoo and Black-whiskered Vireo are best found in the dense hammocks of the Keys. If you were to visit Cuba or the Bahamas, you would see these species breeding and foraging in nearly the same tree species.
The same goes for migrating passerines. During the fall at Long Key State Park, where there are a few parcels of hardwood hammocks, we see some of the highest numbers of migrants using the hammocks to rest and forage. The fruiting trees and shrubs have proven to be extremely important, perhaps even vital to large numbers of migrating thrushes, vireos and flycatchers. American Redstarts, Worm-eating, Black-and-white, and Black-throated Blue Warblers are among several species of warblers that can often be found deep in the interior of a hammock’s middle and upper stories, while Ovenbirds, Swainson’s and Kentucky Warblers comb the ground level where there is often very little sunlight penetration. Common Nighthawks and Chuck-will’s-widows seem to rely heavily on this habitat for roosting during migration.
Along with a menagerie of breeding and migrating species, there have been several that were certainly not expected. Within the state park just in the second half of September of this year, this habitat has accommodated three exceptional vagrants: Key West Quail-Dove (9/27/14), Yellow-green Vireo (9/24/14), and Sulphur-bellied Flycatcher (9/17/14). The quail-dove and the flycatcher frequented the Golden Orb Trail, while the vireo was located in a nearby restricted area where the Florida Keys Hawkwatch team has been granted permission to survey.
As touched upon before, the botanical composition of a hardwood hammock in the Keys is nearly a mirror image of those found elsewhere in the West Indies. If you were to examine and compare the North American bird species that winter in hardwood hammocks in Cuba and the Yucatan, you’d also see that there is a lot in common with extreme southern Florida and the Keys (i.e. the Black-throated Blue Warbler). Similarities in climate between the Keys and the West Indies help explain how this is possible, but here is some literal food for thought: birds are often vehicles for transporting seeds and berries to foreign locations. It is likely that the strong-flying and exploratory White-crowned Pigeons helped aid the colonization of many of the plants found in the Keys. Fruit ingested by a pigeon gorging in a hardwood hammock in Cuba might have come out the other end in the Keys after a hop over the Straits of Florida, an easy flight for a pigeon. Or maybe the secretive and unforthcoming Key West Quail-Dove, which historically may have bred in the Keys, also played a role?
However, there is no denying the threats to such a unique and spatially restricted habitat. In the Keys and coastal South Florida, any dry land is prime real estate for humans. Much of the developed areas of the Keys were historically hammocks, and tracts of this West Indian habitat are now more-or-less restricted to protected areas. Human encroachment has fragmented this highly valuable habitat up and down the Keys, but the hardwoods of Long Key State Park are still very much for the birds.
We are having a great start to the 2014 raptor count this season! We will be at Curry Hammock State Park daily through November 2nd of this year. Please come visit us. Below are our numbers to date. While we’ve had a fantastic season for Ospreys, and Peregrine Falcons are keeping up with expected numbers, October 5 gave us an excellent push of Sharp-shinned Hawks – 512, Cooper’s Hawks – 125, and American Kestrels – 513! The 199 Peregrine Falcons counted that day were not so bad either!
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THERE IS ABSOLUTELY NO DOUBT THAT WE ARE HAVING THE BEST SEASON FOR MIGRATORY OSPREYS IN THE FLORIDA KEYS
New FKH records broken this season for migratory Ospreys:
- Highest seasonal count: 2949 (and 31 days to go)
- Highest single day count: 394 (Sept. 25, 2014)
- Highest hourly count: 301 (15:00-16:00 hr, Sept. 25, 2014)
- Four of the top six all-season highest day counts:
- #1 – 394 (Sept. 25); #3 – 316 (Oct. 1); #5 – 240 (Sept 13); #6 – 229 (Oct. 2)
As of today, we are at a 79% increase for Ospreys over our previous seasonal max (fall of 2002), 163% over our all-season Osprey average, and 93% over 2013’s count for that species!
However, it is important to keep in mind that this year we started counting from the Curry Hammock site 13 days earlier than most seasons. Our typical project start date is September 15, but in order to expand opportunities for the monitoring of migratory kites and songbirds, we started on the second of the month. Only during 1996-97 have standardized counts for migratory raptors taken place before September 15. This year, we counted 771 Ospreys during that period.
If we were to consider only the remaining 2178 Ospreys – counted from September 15 through Oct 2 of this year – this season would still be the highest count for the species in project history, at 32% over the prior seasonal max (2002), 94% higher than average, and 42% over last year’s count.
301 Ospreys in 1 Hour!
On September 25 of this season, we experienced a spectacular flight of 301 “southbound” Ospreys during the final hour of count, starting at roughly 15:00 hr. As can be seen from the chart above, no more than 35 Ospreys had been counted in a single hour prior to 14:00, and a total of 93 had been tallied up to that point. While the winds had ranged from 3 to 12 km/h out of the ENE for most of the day, a sudden squall line pushed by a shift of 15-21 km/h winds out of the east crossed over Little Crawl Key at around 15:50, accompanied by dense and low cloud cover, and hard pelting rain.
Rain continued for nearly an hour. What followed was a low flying “mat” of back-to-back Ospreys in slow flight over the trajectory of the Keys’ island chain, towards the SSW. At times, dozens of Ospreys could be seen simultaneously. SW and away from our count site, the horizon was dotted with them; at one point I counted about 35 Ospreys in a single binocular view. By the time that hour was over, we had tallied 301, bringing our day’s total for that species to 394, and shattering the previous single-day high count of 340 from 2003!
We have known for some time that many Ospreys don’t follow the island chain as they migrate southward, but rather cross over any point of the Keys from the Florida mainland as they continue directly over the water towards Cuba. It is therefore assumed that we miss many of those Ospreys if we are too far to detect their brief crossing over the islands. You may read more about this phenomenon on our post from September 22, 2013 – Ospreys On The Move.
In the case of the Sept. 25, 2014 event, the sudden shift and increased speed of winds accompanied by the squall line must have pushed birds towards the Middle Keys. These were Ospreys that would have been flying east of us over the water and in direction towards the Caribbean, but were forced westward by weather.
Above are maps from 2012 that illustrate the perceived flights of Ospreys as viewed from the FKH count site at Little Crawl Key, which appear to continue directly over water in general direction towards Cuba.
Ospreys tracked by R. Bierregaard, Jr. (above) at the UNC-Charlotte Biology Dept. with the use of satellite transmitters demonstrated a direct southward flight in some Ospreys as they left the peninsula, flew over Florida Bay, bypassed the Keys and crossed over the Straits towards Cuba. You can read more about the work at http://www.bioweb.uncc.edu/bierregaard/ospreys.htm.
The Florida Keys aren’t just a special place to observe migrating raptors – there are opportunities to observe large numbers of migrating shorebirds, herons, and of course, passerines. Starting in 2011, the counters at Curry Hammock began recording all non-raptor species detected at the site. And in 2012, standardized morning surveys at Long Key State Park also were set into motion.
Since beginning our surveys September 2 of this year, we have been watching migration build and continue to gain momentum. Early September saw high numbers of swallows, Eastern Kingbirds, and Prairie Warblers, but overall diversity just wasn’t there yet. Gradually, diversity began to increase as the month moved along, but it wasn’t until the morning of September 18 where a large pulse of new arrivals made landfall in the middle Keys. Early that morning, dozens of thrushes and hundreds of Bobolinks could be heard overhead at Long Key State Park. As dusk turned to day, passerines aloft began to put down in the tropical hardwood hammock. Numbers of Red-eyed Vireos rallied around fruiting Poisonwood (Metopium toxiferum) while Veery “quivered” nervously in the understory. Warbler numbers appeared to have increased compared to those we had seen over the past few days. Although the composition of species was that typical of that of mid-to-late September, a late Louisiana Waterthrush ran among the prop roots of Red Mangroves (Rhizophora mangle). A couple Prothonotary Warblers, another species which often favors mangrove forest during migration in coastal Florida, blitzed into the mangroves as we left the park for Curry Hammock and the hawkwatch.
It wasn’t until we reached Curry Hammock that we realized just how many passerines had moved into the Middle Keys in the morning. Diversity was high, although the individual numbers weren’t. Just in the vicinity of the hawkwatching platform, we would tally eighty species for the day. Seventeen of them were warbler species, and among them were species we often get in low numbers throughout the season: Blackburnian, Chestnut-sided, Hooded and Prothonotary. Also in the mix were the first Tennessee Warblers of the season and an unseasonable Palm Warbler. Two Dickcissels made a brief appearance in the campground, giving themselves away with their unique call. Buttonwoods (Conocarpus erectus) dripped with orange Baltimore Orioles, Red-eyed Vireos, and a variety of warblers. Also of note was another large nighthawk movement. Although a few thousand shy of a single-day count from earlier in the month (Sept 10, 2014), we would tally a healthy nine-hundred seventy-two for the day.
Curious to see what the day brought as it progressed into late afternoon, a return to Long Key State Park was in order after leaving the hawkwatch. This time around, we would observe a relatively new set of birds. Maybe new birds had made landfall after we left earlier in the morning, or perhaps they were overlooked. Or more likely, it was a bit of both. In the same stretch of trail we had been earlier there were parties of strutting Ovenbirds, and easily-overlooked Empidonax species came in the form of Acadian and silent “Traill’s” Flycatchers. A vocal Hooded obliged us with a hollow and metallic “dink” call from thick undergrowth, and finally an Alder Flycatcher announced it’s identity with insistent “pep” calls. The last highlight of the afternoon came in the form of the day’s nineteenth warbler species, a male Kentucky Warbler that hopped furtively through a heavily-shaded hammock.
Several reasons contribute to the opportunity to observe high diversity of migrating passerines in the Keys. For one, the Middle and Lower Florida Keys appear to get species from two different flyways. With a heavy influence of Atlantic Flyway and Caribbean-bound migrants, the Keys also make up the easternmost boundary of the Gulf of Mexico. This often means Trans-Gulf migrants make landfall in the Keys, especially after western winds over the Gulf. The farther south one goes in the island chain, the more likely one will stumble upon Trans-Gulf migrants. Secondly, there is a bottle-necking effect. Birds travelling down the Florida peninsula have the luxury of spreading over a large swath of landmass. As they move into the Keys, their options diminish, and they funnel down the islands until reaching their jump-off point to Cuba, the Yucatan, or elsewhere. Lastly, the insect-laden hardwood hammocks and mangroves also offer a variety of energy-rich fruiting trees. All of these are important ingredients for a show-stopping fall migration in Florida’s unique coral archipelago.
The Sulphur-bellied Flycatcher (Myiodynastes luteiventris) is currently in the Review List of the Florida Ornithological Society‘s Records Committee (FOSRC). Review species are those whose status is poorly known or documented in Florida. Normally, a species with 10 accepted records will be removed from the list, but the committee may remove species from the list, or retain species on the list, as it believes best serves the interests of Florida ornithology. Anyone who finds this species in the state of Florida is encouraged to submit a report to the FOSRC.
- September 17, 2014 - As we were about to finish our daily transect count at Long Key State Park at roughly 9:45 am, Moe Morrissette and I came upon a Sulphur-bellied Flycatcher, perched in the canopy of the rockland hammock sector of the Golden Orb Trail. The bird was within a cluster of mature Gumbo Limbo and Poisonwood trees. Seconds after being detected, it moved gently into a deeper nook of the hammock and was lost from sight.
We tried for several minutes to relocate the flycatcher, but if you have ever birded in a West Indian hardwood hammock, you know how dense the vegetation is, and how easily birds get lost in this jungle-like habitat. My fear was that we may not have the chance to relocate the bird to obtain a photograph for documentation. The occurrence of Sulphur-bellied Flycatcher in Florida is not well understood, and very few documented records exist for the state – none to my knowledge from the Florida Keys proper – although there are records from Cape Florida and reports of Myiodynastes sp. from the Upper Arsnicker Keys in Florida Bay. Familiar with the challenges presented in Florida by a small group of occasional and/or hypothetical “streaked” flycatcher species in the genera Myiodynastes, Legatus, and Empidonomus, I realized I had to quickly put on paper every detail I remembered from the brief encounter with the bird in question to secure documentation.
Out of habit, my immediate reaction was to draw as detailed a sketch of the bird as my memory allowed, before too much time elapsed. Within ten minutes of having last seen the bird, I drafted the sketch above.
Unable to relocate the flycatcher during the morning, it was not until the afternoon, after the hawkwatch was over, that members of our team were able to go back to Long Key and look for the bird. Kerry Ross and Alexander Harper did not take long in finding the bird within the vicinity of where it was first detected.
Separating Sulphur-bellied from Streaked Flycatcher: Although this flycatcher was difficult to photograph through the canopy, Kerry Ross and Alex Harper were able to capture the field marks that allow us to separate the bird in question from its similar congener, Streaked Flycatcher (Myiodynastes maculatus). Both Streaked (19.5 – 21 cm) and Sulphur-bellied (20.5 cm) Flycatchers are rather large, with strongly marked plumage. All members of this genus exhibit large bills with flesh-colored bases to the lower mandible, bold facial masks and varying amounts of rufous on the tail and/or wing feathers.
Consider the following when separating Sulphur-bellied from Streaked: a) The extent of the dark malar markings across the chin; b) the amount of streaking on the belly and undertail coverts, and the yellow coloration of the underparts; c) the coloration of primary feather edging; d) the overall whiteness of the “background” of the facial region; e) the extent of rufous on the tail and uppertail coverts.
a) Sulphur-bellied shows broad dark (blackish) streaks across the malar region that join below the bill, therefore it often appears to show a black and/or streaked upper chin. The malar markings of Streaked are thinner and extend to the base of the bill, but do not join, therefore the chin appears pale. The austral migrant form of Streaked (M. m. solitarius) may show streaking on the throat and chin, as in Sulphur-bellied.
b) As its name indicates, Sulphur-bellied shows a yellow wash from the undertail coverts through the belly and fading into the breast. The austral form of Streaked shows a paler yellow tinge throughout its underparts that rarely reaches the intensity of Sulphur-bellied. Most importantly, the yellow belly and undertail coverts of Sulphur-bellied are mostly unstreaked and clean, except perhaps towards the flanks. By contrast, Streaked Flycatcher shows bold streaks throughout the flanks and into the belly and undertail coverts.
c) The color on the edge of the primary feathers varies between both species. The primary edging of Sulphur-bellied is whitish, while it is rufous tinged or yellowish in Streaked.
d) The “background” color of the facial region and throat plumage, including the supercilium and moustachial stripe are white in Sulphur-bellied, rarely tinged with yellow. These are tinged yellow in Streaked.
e) While both species show a significant amount of rufous on the tail and uppertail coverts, this is most prominent on Sulphur-bellied. The “expected” form of Streaked Flycatcher – the austral migrant solitarius – shows thin rufous-tinged edges to an otherwise dark brown tail. By contrast, the tail of Sulphur-bellied Flycatcher appears largely rufous, with dark centers and a rufous uppertail with sparse streaking.
The markings captured in the photos by Alex Harper and Kerry Ross show the necessary traits for the elimination of Streaked, and in favor of Sulphur-bellied Flycatcher. While Streaked Flycatcher has never been documented in Florida, beware of the smaller yet similar Piratic (Legatus leucophaius) and Variegated (Empidonomus varius) Flycatchers, both of which have been documented in the state.
Left: Rafael Galvez sketching the bird on site, within 10 minutes after the first detection. The possibility of not relocating the bird made this exercise useful for identification. Right: Alex Harper celebrates the relocation of the flycatcher later the afternoon of Sept. 17, while Kerry Ross and Brehan Furfey focus on the bird.
South-bound migration was the agenda for Ospreys moving through the Florida Keys today. Inclement weather and unfavorable winds appeared to have had a bottleneck effect on migrating raptors the day before. The total number of Ospreys detected at the hawkwatch on September 12, 2014: one. And the day before that brought a respectable thirty-eight.
Ospreys wasted no time making up for a day spent hunkered down farther north the day before. When the hawkwatch opened at 9:00 am, Ospreys were already on the move; in the first two hours, 135 were detected. Numbers of them would remain consistent throughout the day, and as thermals began to form, we began seeing birds at higher altitudes. Small groups could often be seen riding thermals with Magnificent Frigatebirds, gaining height with every wide turn. Then, one-by-one at the most favorable height above Earth’s surface, they would follow the same trajectory for landmasses farther afield. Once in a strong glide, one could watch an Osprey disappear to the south, all without one beat of a wing. The birds also seemed to be following two different flight lines. The majority appeared to be following the Keys, island hopping possibly until reaching the Lower Keys before making the jump to Cuba or Central America. But as the day went on, we saw more and more making a bee line for Cuba. Apparent Cuba-bound birds also seemed to be the highest-flying on average. Birds following the Keys appeared to be cruising at lower altitudes.
By the end of the day, the hawkwatchers would tally 240 Ospreys. This number makes for the third highest day total for the Florida Keys Hawkwatch, and only nine behind the second highest (249 on 9/25/2002). A lull in southbound activity around 4:00 pm made beating the second highest total seem a bit more distant. It wasn’t until driving north on US-1 towards Long Key that we could see just how many Ospreys were still moving through the Keys. Forty-six more were located between Marathon and Long Key, most of which were southbound. Yet another storm had been keeping these birds from moving south as the afternoon went on, so who knows what the end-of-the-day count could have been?
CLICK IMAGE TO PLAY VIDEO. Above, a resident “Ridgway’s” Osprey kept an eye on the sky as migratory birds of its species continued moving overhead. Often, as it spotted a migrating Osprey, it would make a plaintive call. To learn more about this Caribbean subspecies, read “Observing Ospreys,” by Jeff Bouton. Video by Rafael Galvez – Leica V-Lux 4.
A breathtaking total of 4,275 nighthawks – presumed Common Nighthawks (Chordeiles minor) – were tallied today between 09:30 and 14:39 hrs from the FKH observation deck at Curry Hammock State Park, Little Crawl Key.
For the past fall seasons we have been documenting large numbers of migratory nighthawks engaged in diurnal flights due south, detected as they cross the narrow landmass of the Middle Keys and continue southward over open water in general direction towards Cuba.
Today we surpassed our high counts of nighthawks from all previous years. Time and again we witnessed the passage of nighthawks in flocks ranging from roughly 70 to 500 individuals each, sometimes coming directly over our count site, other times spotted over a kilometer away. Nearly all flocks trended S to SE, and were tracked as the birds moved towards the ocean, and were finally lost in sight. Our hourly count was 568 (09:00-10:00 hrs), 254 (10:00-11:00), 1739 (11:00-12:00), 1079 (12:00-13:00) and 635 (13:00-14:00) for a total of 4275!
The weather was quite variable in the Middle Keys this day, with winds ranging from 2-13 km/h pushing bands of clouds and rain over the region. Cloud cover in general was dense and low, averaging 79% throughout the day (100% 13:00-16:00 hrs), and as low as 1500 ft in altitude. The map above (left) shows blue arrows indicating the general trajectory and line of detection of nighthawks crossing our monitoring area. The radar image on the right shows weather over South Florida from 1pm – 2pm.
Counters were Kerry Ross, Brehan Furfey, Alexander Harper, Moe Morrissette and Rafael Galvez.
Additionally, we tallied an impressive 790 southbound Eastern Kingbirds, 2195 Barn Swallows, and many individuals of numerous migratory bird species – culminating in an unforgettable day of migration in the Florida Keys!!!
Mantengan un vistazo al cielo en Cuba – alla van los Querequetés migratorios!!!