Date: Sun, 6 Oct 2002 04:12:51 -0400 Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding From: Phil Davis Subject: Re: Mystery Heron/Egret (very long) In-Reply-To: <000701c2416d$be7255c0$d07d4e0c@Norm1> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed >At 15:31 08/11/2002 -0400, Norm Saunders wrote: >A query to all of you knowledgeable folk out there: > >Are there any large, dark herons/egrets that utilize the same fishing >strategy as the Reddish Egret? I am referring to the prancing with wings >extended, head and neck down fairly close to the water. [Note all of Norm's original message is posted at the very end of this message] Hi Norm, et al. - I was not knowledgeable on this subject, but your question intrigued me. I didn't see any replies so I was finally able to scratch enough things off of my "to do" list so I could look into this... (hey, it only took me about 7 weeks !). Here's what I found ... My primary source on heron/egret behavior was: Hancock, James and Kushlan, James, 1984. The Herons Handbook, Croom Helm [UK]. Hancock classifies and describes various heron movements and then applies these descriptions to each species. Here are some relevant extracts from his text ... BODY MOVEMENTS [note: other body movement descriptions not relevant and have been deleted - PCD] "Herons are Walking Quickly when their steps become faster than 60 per minute. Walking Quickly covers more ground than intermittent Standing or Walking Slowly, and tends to disturb more prey. As a result, it is often considered to be a disturb or chase behaviour, but it may also be used merely to move quickly from one place to the next. Several species frequently use the Walking Quickly technique, including the Cattle Egret, Reddish Egret and Tricolored Heron. A Running heron dashes about, usually to chase after specific prey items. It often moves so quickly that it uses its wings for balance, to gain lift to move faster, and for stopping (Rodgers 1983). The medium-sized marine-foraging species, especially the Reddish Egret and the Eastern Reef Heron, often specialise in such behaviour .Cattle Egrets run frequently in terrestrial feeding habitats." WING MOVEMENTS "Use of the wings while feeding is fairly common. In some behaviours wings are used by Standing or Walking birds. While Wing Flicking, a heron quickly partially extends and then retracts one or both wings. While Open Wing Feeding, a heron extends one wing and leaves it extended for a few seconds before retracting it. While Underwing Feeding, a heron puts its head under an open wing in order to strike at a prey item. While Double Wing Feeding, a heron brings both wings forward and holds them over its head. While Canopy Feeding, a heron brings both wings forward above its head so that the forward edges meet and feather tips dip in the water; this forms an umbrella over the heron's head and neck. These wing movement behaviours may function in different ways. Wing Flicking and Open Wing behaviours are probably used to disturb prey, whose consequent movements increase the heron's chances of seeing them. Underwing, Double Wing and Canopy Feeding reduce glare, making prey more visible, and may attract prey to the shade formed by the wings. Canopy Feeding is often assumed by a heron with its back to the sun. Although many herons use these behaviours, some do so characteristically, Open Wing Feeding is typical of the Reddish Egret, which often uses it before Running about, and is probably employed primarily on shoaling fish. Pied Herons, Tricolored Herons, Snowy Egrets and reef herons also use it. Underwing Feeding is also used by Tricolored Herons and by Reddish and Snowy Egrets. Double Wing Feeding is used especially by Reddish Egrets, but, so far as is known, only Black Herons use Canopy Feeding. This latter species walks or runs from place .to place, stopping every few steps to form a Canopy over its head." FOOT MOVEMENTS "Use of the feet while feeding is common in some species and has been reported sporadically in many others. Foot movement behaviours that have been described include Foot Stirring in which the foot and leg are vibrated, Foot Raking in which the toes are scratched across the substrate, Foot Probing in which the toes are inserted into the substrate, and Foot Paddling in which the feet are moved up and down on the substrate. Several of the species that frequently use Foot Stirring behaviour, such as Snowy and Little Egrets and Black Herons, have feet that are more brightly coloured than their legs. This suggests that the foot movement is used to startle prey and cause them to move. Foot movements are often used in mud or vegetation. The Snowy Egret is a foot movement specialist and is known to use each one of these behaviours. Reddish Egrets, Tricolored Herons and Green-backed Herons use both Foot Stirring and Foot Raking." So, it would seem very possible that you may indeed have had a Reddish Egret, since it sounds like you were able to eliminate Tricolored Heron. The only other heron, worldwide, that would seem to fit, according to Hancock and Kushlan (1984) is the "Eastern Reef-Heron". The only other reply posted to your original message came from Paul O'Brien who stated, "Another possibility is Western Reef Heron. Look for yellow feet and a white throat. It has been seen in Massachusetts and probably came via the West Indies." So, all of this leads us to Eastern and/or Western Reef-Herons as alternatives. Not knowing anything about Eastern Reef-Herons and only a little about Western Reef-Herons, I dug a little deeper. I learned, however, that the taxonomy of "Reef Herons" is highly unsettled. To quote from the Handbook of Birds of the World, "In the last 100 years, the family [Ardeidae (Herons)] has been composed of anything from 15 to 35 genera and 60 to 93 species." Without going into detail (and avoiding scientific names), the Western Reef Heron (that Paul mentioned) is now considered by many authorities to be a subspecies of the Little Egret. The same is true for what was previously considered to be the Eastern Reef-Heron. Studies in the Pacific indicate that the running-type behavior, described by Hancock, is more commonly used by dark morph birds. Furthermore, dark morph birds are more common inland and on dark beaches while white morph birds are more common on light beaches. The Western Reef-Heron/Little Egret complex has been recorded numerous times in North and South America (at least 40 birds as of October 1991) however; the occurrence of dark morph forms has been less than 25 percent. It does not appear to me from the literature that birds of this African-centric dark morph group exhibit the active feeding strategy you described, but this would be a generalization. The former Eastern Reef-Heron, like Reddish Egrets, also comes in two flavors, a white morph and a dark morph, but is found in eastern Australia, New Zealand, and Indonesia and is basically non-migratory and exhibits little post-breeding dispersal. Therefore, a dark-morph "Eastern Reef Heron", the type most likely to exhibit the feeding behavior you witnessed, would be a truly remarkable North American record. So, sounds to me like a good bet it was a Reddish Egret!!! I take it that no one ever relocated the bird ... ? This was fun and I learned a lot ... Thanks. Phil Literature Cited: Hancock, James and Kushlan, James, 1984. The Herons Handbook, Croom Helm [UK]. Rohwer, Sievert, 1988. Foraging differences between white and dark morphs of the Pacific Reef Heron egretta sacra. Ibis 132:21-26. Forster, Richard A., 1989. First United States sight records of Little Egret. Bird Observer 17(5):239-244. Murphy, William L. and Nanan, Winston, 1987. First confirmed record of Western Reef-Heron (Egretta gularis) for South America. American Birds 41:392-394. Itoh, Singi, 1991. Geographical Variation of the plumage polymorphism on the Eastern Reef Heron (Egretta sacra). The Condor 93:383-389. Crossland, Andrew C., 1992. First record of white phase Reef Heron (Egretta sacra) in New Zealand. Notornis 39:233-234. del Hoyo, Josep et al. eds, 1992. Handbook of the Birds of the World Volume 1. pgs 376-413. Murphy, William L., 1992. Notes on the Occurrence of the Little Egret (Egretta garzetta) in the Americas, with Reference to Other Palearctic Vagrants. Colonial Waterbirds 15(1):113-123. Ashkenazi, Shoshanna, 1993. Dark-Morph Individuals of the Egretta spp. in Israel. Colonial Waterbirds 16(2):202-207. Norm's original full message follows ... At 15:31 08/11/2002 -0400, you wrote: >A query to all of you knowledgable folk out there: > >Are there any large, dark herons/egrets that utilize the same fishing >strategy as the Reddish Egret? I am referring to the prancing with wings >extended, head and neck down fairly close to the water. > >In any event, regardless of the answer, over the past week, Fran and I >observed a bird exhibiting this behavior twice, feeding off of a sandbar >along the backside of Assateague Island about a mile or so south of the >northern tip of the island. We observed the bird dancing as noted above on >both occasions, the first the morning of 4 August and the second the morning >of 10 August. > >The bar was a good 3/4-mile away from our viewing position on the mainland >shore on the bayside of Mystic Harbor. Even with a scope the view was less >than great--lots of heat waves to contend with. We watched the bird for >about five minutes the first morning, before it flew further south down >Sinepuxent Bay. On the 10th, we saw the bird only for a short period, a few >minutes or so, until it was frightened by a passing motorboat and flew over >to the mainland side of the bay well south of our viewing position and out >of sight. > >Once again, the bird was on the large side, with dark back and wings, and no >noticeable color contrast on the breast as it flew off. If anyone else sees >a similar bird in this locale, please post details here. A Reddish Egret >would be a long-overdue addition to the Maryland State List. > >We'll likely be back in the area this coming weekend and will check the >flats from Eagles Landing campsite but if anyone else is in the area this >week, please try to look for this bird. ================================== Phil Davis Davidsonville, Maryland USA mailto:PDavis@ix.netcom.com ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= ================================== =========================================================================