Temporada loca

immature Mississippi Kite

As I wrote a couple of blog posts ago, we're seeing higher numbers than usual of Mississippi Kites here in Pronatura's Veracruz River of Raptors migration watch this year. In fact, last week we broke the previous season record of Mississippi Kite, dating from 2002 when 306,274 individuals were counted. We're now at 316,470 - and counting! They're still coming through in good numbers, although Tropical Storm Nate has interrupted the flow momentarily. Birds are likely bottling up north of us, and we may have a big flight on our hands when skies clear on Tuesday or Wednesday.

Mississippi Kite about to catch that dragonfly

The first cold front of the season last week brought migrants that are generally expected a bit later in the season, like Swainson's Hawk, Turkey Vulture, Northern Harrier, and American Kestrel. The broadwing flight also got underway, with almost a thousand individuals moving through these past days. And the first Hook-billed Kites of the season have been recorded - those birds at least perfectly on schedule.



A strong Mississippi Kite flight on the 7th of September produced a wonderful lift-off the next day, when for about an hour and a half we had a constant stream of low-flying kites in Chichicaxtle at the start of the count. Several thousand birds had spent the night in the surrounding areas and were trying to gain lift from the first developing thermals that day. Some of them hunted the also abundant migrant dragonflies.

our resident Zone-tail with an Inca Dove it just caught

An adult rufous morph Swainson's Hawk on the 3rd of September was the earliest ever recorded by the project. (A couple of days later, the Pronatura hawk banders caught a Swainson's Hawk in nearby Cansaburro, their earliest ever capture of this species.) Another unusual phenomenon thus far has been the high number of Zone-tailed Hawks this season. We're already at 77 migrants for the season, when until this time last year only 7 had been recorded.


Clearly, 2011 is exceptional, and the counters here speak of a "temporada loca" (crazy season).

Late nesting of Buff-bellied Hummingbird

While birding the area near the Pronatura River of Raptors observation tower in Chichicaxtle this morning, Pablo Camacho and I found a female Buff-bellied Hummingbird - incubating! According to Howell & Webb (1995), the nesting period for the eastern Mexico population is April to July, while the Yucatan population breeds February to April.

Buff-bellied Hummingbird occurs in coastal Texas, where it appears to be expanding its range (Lockwood & Freeman 2004). According to the BNA account, breeding takes place in south Texas between mid-March (first eggs) to early October (last fledglings), with the majority of fledglings around between late May and late August (Chavez-Ramirez & Moreno-Valdez 1999). These authors mention two nestlings observed in October in south Texas, suggesting that eggs were laid in September. Our bird is nesting late, but not unheard-of late.

It's nesting in someone's yard, at the edge of the baseball field that we look on to from the hawk observation tower. I'll be sure to check in from time to time, to get a sense of when the eggs will hatch, and when the young will fledge. Let's hope the nest survives tropical storm Nate, scheduled to make landfall here in Veracruz tonight.

Cited literature:
Chavez-Ramirez, Felipe and Arnulfo Moreno-Valdez. 1999. Buff-bellied Hummingbird (Amazilia yucatanensis), 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/388
Howell, S. N. G. and S. Webb. 1995. A guide to the birds of Mexico and northern Central America. Oxford Univ. Press, Oxford, UK.
Lockwood, Mark. & Brush Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University press.

A good kite year

This is obviously a good kite year here in Veracruz, Mexico. At September 5, the 2011 Veracruz River of Raptors count had already logged 266,166 Mississippi Kites and 213 Swallow-tailed Kites, with both species still coming through in some numbers. Especially Mississippi Kites are expected to continue for some time in the order of thousands a day, usually trailing off to hundreds a day by late September. They still pass through in October, but in very small numbers.

Looking at counts from 2002-2011 (www.hawkcount.org), we see that this year we've already surpassed the seasonal totals for Mississippi Kite of 2003, 2004, 2005, 2006, 2008 and 2009. We will likely exceed last year's count (274,621), and have a real chance at breaking the exceptional 2002 record of 306,274 Mississippi Kites. The mean number of Mississippi Kites recorded at the two Veracruz count sites combined for the period 1995-2004 was 157,199 (Ruelas Inzunza 2007). The species' recent expansion of its breeding area has been well-documented by excited northeastern birders, and that expansion is reflected in the higher recent counts in central Veracruz, where virtually the entire world population is believed to pass through a relatively small area each fall.

We're also seeing more Swallow-tailed Kites this year than were recorded on average for the period 1995-2004, but we are still far away from the exceptional 2007 seasonal total, when a new record was set with 563 Swallow-tailed Kites. The  average number of STKI for the period 2002-2010 is 275, a number we seem to be on track for this year.

For other raptors it is of course still way too early to say anything about trends. We have had an unusual number of Zone-tailed Hawks already, but this and many other species normally peak late September / early October, when we will have a much better idea about how this year's numbers fit into the larger trend line.


Cited literature: 
Ruelas Inzunza, E. (2007) Raptor and wading bird migration in Veracruz, Mexico: spatial and temporal dynamics, flight performance, and monitoring applications - Dissertation University of Missouri - Columbia.

Anhingas

Yesterday, the river of raptors here in Veracruz was momentarily dwarfed by the river of Anhingas. In Cardel, Citlali, Lynn and I counted 'only' 3,001 Mississippi Kites, a number that would be astounding at any other North American hawk watch, but early September in Veracruz is easily dismissed as 'nothing much'. And indeed we saw more Anhingas than Mississippi Kites, which does not happen very often.

In Cardel, we ended up with a count of 3,622 migrating Anhingas yesterday. Like raptors, they are diurnal migrants depending on thermals for lift, and are often found kettling up and then streaming out in search of the next thermal. Unlike raptors, they tend to all move synchronized when riding a thermal, a character that serves as an identification clue at great distances.

The species is resident in the area, but resident populations are augmented with northern migrants during the winter. eBird's Anhinga filter insists that any count over a few hundred individuals is a "great number" that it wants me to confirm, but counters and visitors to the project know that it is by no means unusual to see more than a thousand Anhingas in just one day here.

Seasonal counts at the site during the period 1995-2004 yielded a seasonal average of 31,000 individuals (Ruelas Inzunza 2007), with the 2002 count being exceptional with 40,000 Anhingas counted, i.e. 20% more than the estimated entire North American population! Clearly, those estimates need to be updated. This count in Veracruz provides valuable data not only for population estimates but also for population trends.

Cited literature:
Ruelas Inzunza, E. (2007) Raptor and wading bird migration in Veracruz, Mexico: spatial and temporal dynamics, flight performance, and monitoring applications - Dissertation University of Missouri - Columbia.

Aplomado Falcon

Today some photos of a juvenile Aplomado Falcon, which I took in the dunes near Playa Juan Angel in central Veracruz. This charismatic species, once rare and endangered, is making a healthy comeback, and can now be found throughout the coastal plain of Veracruz.  We sometimes see this species from either of the two Pronatura count sites, and it is virtually a guaranteed sighting when birding anywhere in the coastal dunes.

They're about the size of a Peregrine, but are easily told from that species, even at some distance, by their much longer tail. Closer views reveal pronounced plumage differences such as a whitish eyebrow, a black hour-glass shaped belly patch, orange leg feathering, dark underwing, pale trailing edge of wings etc.

Juveniles, like this individual, show a heavily streaked breast. The breast is unstreaked in adult males, and with only a hint of streaking in adult females.

The leg feathering is pale orange on juveniles, darker orange on adults. There's also a difference in the color of the eye ring and cere: blue on juveniles, yellow on adults (like in Prairie Falcon).

A social raptor, they are often found in loose family groups.