Disregard that first email. In a message dated 8/15/2012 8:00:05 P.M. Eastern Daylight Time, williamwatso...@aol.com writes:
Hello New York Birders, Below is a thread on Great Egret night migration on Geneseebirds. Have you seen egrets migrating? Was it day or night? Hawk Watchers, based you experience how many Great Egrets do you see following the migration flight line compared to Great Blue Herons? Please respond. Chip Weseloh _chip.wese...@ec.gc.ca_ (mailto:chip.wese...@ec.gc.ca) and I would like to know. Thank you, Bill Watson At the Hamburg Hawk Watch in Western New York over the years I have seen hundreds of Great Blue Herons following the flight line, but I have only had one Great Egret and it was not following the flight line. Nearby at Iroquois NWR Great Egret Numbers rival Great Blue Heron numbers during migration. Great Blue Herons breed there, but Great Egrets have not bred there until this year. It seems to me that Great Egrets would be much more often seen at the Hamburg Hawk Watch, even if they migrated in the daylight hours say 20% of the time and at night 80% of the time. A year or two years ago I discussed this topic with Kyle Horton who did night migration studies at Powdermill Avian Research Center. He quickly responded that Great Egrets are definitely night migrants, and that their calls are frequently recorded. He then cited collaborating evidence at other nocturnal bird observatories. So I assumed it was general knowledge and old hat information. I am surprised by the Cape May information. I would like to hear opinions on the frequency of migrating Great Egrets vs Great Blue Herons from other Hawk Watchers. Bill Watson In a message dated 8/14/2012 9:36:45 A.M. Eastern Daylight Time, rsp...@prodigy.net writes: Thoughts: Chip, you provided an excellent summary which leads to a well-reasoned conclusion. Not sure how one would move forward from there without careful observations involving birds marked to be identifiable in the field and/or radio tracking of a substantial number of birds. Not sure anybody would fund a study to answer that question for that species given limited resources. Bob ____________________________________ From: "Weseloh,Chip [Ontario]" <chip.wese...@ec.gc.ca> To: williamwatso...@aol.com; geneseebird...@geneseo.edu Cc: sel...@nycaudubon.org Sent: Tue, August 14, 2012 1:40:41 AM Subject: Re: [GeneseeBirds-L] Motor Island Great Egrets at Sunrise Thanks for posting this Bill and prompting further discussion. I think the verdict on this question, "Are GREGs diurnal or nocturnal migrants?" Is still out and they may be both. Some of the things I have learned/seen over the last few years are enumerated below. 1. The BNA account says they are probably diurnal but good data are lacking. 2. When I posed the diurnal/nocturnal migrant question on an ornithological list serve, I heard back from two scientists who monitor nocturnal migration from the tops of buildings (one of which was the Empire State Building in NYC) by continuously recording flight calls. Both of them said they have heard GREGs calling over their buildings at night. 3. A few years ago, I was at the Avalon Sea Watch at Cape May talking to the observers and asked them if they ever see migrating GREGs? They said yes, often. They always leave the mainland and head out over the ocean in mid-late afternoon 3-4-5 PM. 2-3-400 of them per day. 4a. At the large Luther Marsh roosting site, I have seen what I feel to be migration departures in both morning and evening. At least once every year since 2009 at dusk, we have observed egrets fly into the roost like they do every evening only to have many of them, and sometimes all that are at the roost, pick up and fly off to the SW. This has always occurred in late September and always right near or after sunset. This we have taken to be a nocturnal migration departure. 4b. This spring, I got to Luther well before sunrise to watch the AM roost dispersal. I could see about 15 egrets in the roost. Their usual behaviour for AM dispersal, spring or autumn, is to leave the roost in 2s and 3s, or so, and many resettle nearby to forage. On this morning, 18 birds left in two groups, one right after the other, going straight north (towards the Nottawasaga breeding colony about 60 miles away) until I lost them from sight. In my mind they were finishing their northward migration (via a diurnal flight) to Nottawasaga, or points farther north. So, I do think the migrate both night and day. I'm not sure which is more prevalent. 5.From late August to mid Sept, the egrets at Luther decline from 350+ to 200+ and we never see any leave on what we think at diurnal or nocturnal departures. So, I have concluded they go out to feed in the morning, per usual for AM roost departure, feed for a couple of hours and then pick up and fly off without being seen! What are your or other's thoughts? Chip From: williamwatso...@aol.com [mailto:williamwatso...@aol.com] Sent: Saturday, August 11, 2012 01:36 PM To: geneseebird...@geneseo.edu <geneseebird...@geneseo.edu> Subject: [GeneseeBirds-L] Motor Island Great Egrets at Sunrise First I would like to point out that Great Egrets are mainly or completely nocturnal migrants. Some of the evidence comes from Hawk Watches particularly along the Atlantic Coast that can see over 200 Great Blue Herons a day, but no Great egrets. My experience is that you are about 1000 times more likely in seeing a Great Blue Heron following the flight line at a Hawk Watch than a Great Egret. I am also unaware of observations of daytime migratory flocks of Great Egrets, but would like to hear from others on this topic. Also people that count Great Egrets at night roosts have seen flocks of Great Egrets (15-20 egrets) leave the colony in late evening. To study this phenomenon Chip Weseloh set up a protocol for evening an morning viewing of roosts during September-October a few years back to see if morning numbers would be lower that evening numbers confirming that egrets had left the roost at night. As I was a participant I feel I am very experienced with egrets behavior when they leave a roost in the wee hours of the morning. In short, the egrets leave the roost and seldom do they return. Most often all of them at gone before sunrise, but sometimes one or two will stay till after sunrise. This morning I followed Chip's protocol and viewed egrets on Motor Island and Strawberry Island. Every 17 to 3 minutes I wrote down a count on both island and behaviors. sunrise 6:18 sky overcast with dark clouds, but about 5% clear sky in the east favorable flight winds at 7 mph from the south 5:28 very dark but could see 10 Great Egrets on Motor Island and 4 egrets on Strawberry Island Time----- # egrets at Motor Island ---------# egrets at Strawberry Island 5:45-------------10----------------------------------------6 5:45-------------10----------------------------------------6 5:51-------------11----------------------------------------6 5:54-------------12----------------------------------------4 5:59-------------13----------------------------------------1 two egrets have flown in and landed on Motor Island 6:07-------------14----------------------------------------1 6:11-------------17----------------------------------------1 6:16-------------20----------------------------------------1 6:22-------------13shore+5trees---------------------0 6:28-------------10shore+5trees---------------------0 6:31-------------3shore+12trees---------------------0 6:48-------------7shore+6trees-----------------------0 Perhaps what is even more important is that all except for two or three at some time during the study period showed an ability for short flights. Unlike the Strawberry Island egrets and typical egrets leaving a morning roost (which directly leave the roost and do not return) the Motor Island egrets would only fly about 10 feet from one bush or tree to the next. Or they would fly about ten or twenty yards to the shore line. A few brave egrets made circular flights (with a diameter of about 100 feet, Motor Island is almost 1000 feet long) over the water, but landed back at the colony. I only saw three birds leave Motor Island and they were likely the ones that came earlier from Strawberry Island. Based on the behavior of egrets in past years, most of these bird are showing that they are almost but not quite ready to leave Motor Island to forage away from the colony. I believe there are two reasons why the number of egrets reach 20 at 6:16 AM. Many of the birds were active and came out of the foliage that was concealing them. Some of the egrets that left Strawberry Island landed on Motor Island. -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME http://www.NortheastBirding.com/NYSbirdsRULES http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birdingonthe.net/mailinglists/NYSB.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
