Note: This post began as a plea for integrity on the part of environmental advocates but ended up as a fairly long summary of available information on the status of the N. American population of the Red Knot, a summary that suggests scientists need to be more careful with their data. (10-11-12)
When I taught "Historical Methods" I emphasized that when one does research for an honors thesis, etc. or to make a convincing argument in an exam essay or term paper, one must be aware of and examine all facts, including those that may run counter to one's thesis. Rather than an "on the one hand or the other hand" mind set, the students should consider that each hand has 5 fingers, etc. As I was not very successful, I started to use the example of a trial lawyer who is confronted with an opponent who presents a petition to a judge. The petition is based on precedent, e.g X vs. Y. The trial lawyer has to know this precedent and its context in order to present cases that reject X vs.Y as valid ground for the granting of the petition. In academic research, of course, the idea is not to win (which in courtroom cases may lead to innocents being put in jail, for ex. the recent cases in Illinois). The one-sided "lawyerly" approach is well illustrated by the 2008 biography of Roger Tory Peterson, Birdwatcher, written by a lawyer. She produced a hagiography, glossing over important negative aspects of P's personal relationships etc. that belong in a biography. Then there's the recent biography of Rosalie Edge, the sometime suffragette who later founded Hawk Mountain Sanctuary where I spent countless happy hours. At a conference in Tucson, Ariz., the author called Ms. Edge "the Godmother of the environmental movement" which might be overlooked as hyperbole but for the fact that it alters the history of that movement, of which, for ex. the 19th century George Bird Grinnell was a pioneer. In both cases, I think, we meet an author engaged in sales promotion. A good historian presents, where necessary, the most plausible alternative to a received interpretation to help establish a more accurate picture of the past. On the whole, Historians are less subject to financial and other pressures than scientists some of whose sloppy and even fraudulent research was highlighted by a front page article in the NYT Science Section of April 17, 2012. And Th. Piersma et. al., in The Ecologische atlas van Nederlandse wadvogels (1999),[Ec.atlas] also discuss the problems associated with the "privatization" of research funding (pp. 343-4). Other examples of scientific misconduct are given in an article in the NYT of 10-2-12, p.D3.
I got to thinking about this as I was reading one of my magazines about my favorite subjects, namely birds, nature and their conservation. One topic concerned global warming and in letters to the editor, 2 rejected the idea that there was a crisis and/or that it was man-made. The foundation for this was one-sided, viz. the US Senate Environment and Public Works Comm., which is the domain of the ecologically skeptic Senator Inhofe, as well as data from Native Energy (which promotes clean coal etc.) An example cited was the natural cycle of warming and cooling in the past, which is common place in the debate. One writer said not to worry about the polar bear as they had survived the warm period "when the Norse [the Danes?] were farming Greenland [only a small coastal strip then that is now becoming larger but covered with rising sea water] and the Northwest passage was open?" I wonder which Northwest Passage? The reader might think about the Bering Strait named after a Dane. But when was that open? Not when Bering was looking for it nor in the late 16th century when the Dutch under Barents (there is a Barents Sea north of Siberia) tried to get to the fabled East. Was it when the Indians came out of Siberia to settle in the Americas? Would any one think that it was a break in the ice approximately where the Mississippi Valley is now? Millennia ago! Not, of course, when the reference is to Norse agriculture on Greenland. Though the question about the polar bear during an earlier arctic melt down could be important if we find evidence of such a meltdown before or after the polar bear had evolved from the grizzly.
As to whether modern humans cause global warming I go along with scientists who argue that we are. Previous natural cycles could last as many as 15 centuries and since the last cooling (the so-called "little ice age," ca.1500-1750) not enough time has lapsed to account for the current warming or the current rate of increased warming. The salient factor that is different from earlier warming periods is the recent (since about 1700) expansion of the human population and the even faster increase of modern inventions (since about 1850) that cause the accumulation of CO2 in the atmosphere which is accompanied by the destruction of forests worldwide that could absorb some of it. The destruction of forests is not only part of the climate change story, but also of the much more general issue of the worldwide human impact on the environment (i.e. habitat destruction). Some of the scientific information has alarmed the U.S. Navy about the melting of the ice in the arctic seas (D. Mackenzie, "Arctic Meltdown," New Scientist, 2002, 2 March:5).
The polar bear reminded me of a more acute question involving another example of our impact on the environment, namely the connection between the increased fishing of horseshoe crabs, beginning in the 1990s in the Delaware Bay and the decline of the rufa subspecies of the Knot Sandpiper that feeds on the crab eggs to store energy for the flight to their arctic breeding grounds. These Knots are called Red Knots in America, but they are actually only one (or two) of the subspecies of Knots that spread as the last ice age began to recede. Alarm bells have been ringing, New Jersey has a moratorium on the harvesting of the crabs and the Audubon Soc. and others are pressing for the bird's endangered status. To come back to my History Methods model: not merely for the obvious scientific reasons, but in particular for public relations' sake, is it important that conservationists in general and defenders of threatened species or of bio-diversity in particular, do not fail in their goals because they appear to neglect information (let alone suppress it) and thus give fodder to the "Inhofes." At 82, I no longer have the drive to do the sort of research I did for my publications in History, but I have gathered some information concerning the sketchy data of the past occurrence of the Red Knots that I could do as a mostly sedentary birder.
But first a summary of the birds' present status for which we have numerous research papers as well as a 2007 collation of these: Status of the Red Knot Calidris canutus in the Western Hemisphere, by L.J.Niles and others, as well as the 2010 Update (resp. Status 2007 and Update 2010). And I did some clicking on the Internet sites of the New Jersey Fish Commission and some of its links, for ex. the www.ceoe.udel.edu/horseshoecrab/regulations/html (udel.edu) where, among other information, one finds the regulations of the Atlantic States Marine Fisheries Commission (ASMFC).
The debate about the well being of the rufa population of the Knot is fuelled by estimates of 200,000 shorebirds based on aerial counts in the 1980s that were about equally divided between Red Knots, Ruddy Turnstones, Sanderlings and Semi-palmated Sandpipers, i.e. some 50,000 Knots. Incidentally: were Dunlin, Dowitchers and Black-bellied Plovers overlooked or sorted out? These estimates have since been called into question and the high of the 80s has been corrected to approx. 70,000 shorebirds. Yet the old numbers persist in the literature, for ex. D.M.Buehler, B.I. Tieleman and Th. Piersma (Auk, 2010, 127:394-7) open with: "Hundreds of thousands of shorebirds" occur on spring migration in the Delaware bay. And an article in the NYT of June 5, 2012 that describes the banding, etc. at Reed's Beach, N.J., while noting that this year's count of Knots in the Bay are was about double that of 2011, also states that this is way less than the "100,000 of the 1980s." These numbers may be supported by a report on the udel.edu site "Migratory Shorebirds" stating that according to once-weekly aerial counts in May and on June 5, 2001 "the actual number of shorebirds [. . . ] may surpass one million." Yet, the accompanying graph shows a peak for Semi-palmated Sandpipers at fewer than 200.000 on May 30; fewer than 100,000 Turnstones on 5/23; fewer than 50,000 Dunlin on 5/23 and slightly fewer Knots on the same day, which makes significantly less than half a million birds (but still "hundreds of thousands") by adding the peak days for each of these species; it is hardly an "equal" division among species. Using the term "shorebirds" while talking about Knots seems to create confusion. As I pointed out, "shorebirds" includes more than the four species mentioned above. Also: its use in a discussion of Knots leaves the impression that "hundreds of thousands" rely on the horseshoe crab, which is not the case (see below).
Meanwhile I received a beautifully illustrated "coffee table" book Life Along the Delaware Bay. Cape May, Gateway to a Million Shorebirds. Rutgers U.P., 2012. Written by Lawrence Niles and others, it is illustrated with photographs by Jan van der Kam. Both titles are somewhat misleading as the focus (as can be expected from Lawrence Niles) is primarily on the horseshoe crab and the birds that feed on them an in particular on the Knot (for which Cape May is not a major stop over in either season). It has a pie chart showing the peak aerial count for eight primary species of shorebirds in 2008. The explanation refers to "nearly half a million birds in the 1980s" and "fewer than 150,000 in 2010 of which Knots comprise 9% with Dunlin 31%, Semi-palmated Sandpipers 35% and Ruddy Turnstones 13%. Of these the Knots and Turnstones, according to the relevant chapters, are most dependent on the crab eggs.
Research also focuses on counting the number of a species in its Arctic breeding regions [that are affected by global warming] and in their winter quarters [that are also affected] (Morrison, R.I.G. a.o. “Population Estimates of North American Shorebirds.” Wader Study Group Bull. 111:67-85). Apparently not all knots fly to Argentina, for. ex. some winter also along the Atlantic coast and 60 were observed in Stone Harbor, N.J., in February of 2008 and 66 appeared there on the Bay shore in Jan. of 2012 and in yet another winter there were about 100 on Hereford Inlet near the toll bridge to Wildwood; these may belong to a different population, the roselaari.
The rufa Knots are one of five subspecies all of them apparently only geographically separate populations that spread north eastward after the last Ice Age from a rather small number of survivors of the nominate species, Calidris canutus canutus, that lived then on the tundra in what is now Western Europe. Like the rufa population, these nominate Knots are long distance migrants. They winter on the west coast of Africa and farther south; the Dutch Wadden Sea and the Wash in Norfolk, Engl., are their major foraging areas on migration. (One autumn in the 1950s, a few birding buddies and I witnessed a flight of Knots that numbered in the 10s of thousands as they sought higher ground in the Wadden Sea. Apparently they were only a portion of the Knots there). The five subspecies split at different stages as the ice receded. Two of them (Piersmai and Rogersi) breed in northern Siberia, while two others, the Roselaari and Rufa populations spread to Alaska and the Canadian tundra. However these splits occurred, a large population, the Islandica separated from the Canutus in Europe and moved northwest to Iceland, Greenland and the easternmost Canadian archipelago (Ec.atlas, p.144). Observing them from a distance, even now with a scope, I have never been able to distinguish either the Islandica from the nominate in Holland or the Rufa from the Roselaari on the Delaware Bay. I am not the only one having problems, for ex. the Petersen and Burrows Birds of New England (2004) warn against confusion with several other shorebirds (they also note that small numbers of Knots winter along the coasts of Southern New England). I was much relieved when I saw a photo (Status, 2007, p. 9) of two handheld Knots one of which "is believed to be a roselaari." Throughout the Status report its authors refer to the "taxonomic uncertainty" about the populations in the USA (incl. Alaska where Roselaari may be joined by Siberian Rogersi Knots). In the past all these Knots had one name: Tringa islandica. Like other birds, Knots are subject to many problems, for ex. Evans and Penkovski (1984) estimate a 20-30% survival rate of 1st year birds and Baker and Baker (1973) found only a 40-50% fledging success.
I had never seen more than "hundreds" of shorebirds together at one time in May and early June along the Delaware Bay beaches. Even adding the various groups at several spots they numbered perhaps a few thousands, only a small number of Knots among them. When they are feeding on the eggs it is difficult to keep them apart from behind the fences that now protect the spawning horseshoe crabs in many places on the Jersey side. The Delaware Rare Bird Alert recorded 6,000 Knots on a roost near Mispillion at the end of May in 2011, most of which any birder could observe. When feeding, the birds jostle each other onward or out of the way and some, having ended up on the back of the spawning crabs confound my attempts to identify those on the other side. In their feeding frenzy they appear oblivious to their surroundings. The first time I saw this phenomenon was on the then still very small beach at the Forsythe (Brigantine) NWR. We stood together with several other birders on the dyke right above the egg laying crabs and the gorging birds. They were nearly all Semi-palmated Sandpipers, perhaps a hundred, pressed together so closely that one could see no sand between them and the crabs. The few Dunlin and Turnstones stayed out of the fray and fed on the edges among the Laughing Gulls; no Knots. Actually among the flocks I see each spring on the beaches, the Semi-palmated Sandpipers are always the most numerous though in some spots Turnstones dominate, like on the beach remnants along the rock reinforced road at Port Mahon in Delaware. When I am there Knots are rare, for ex. on May 18, 2012 I found nine along the road, but the Del. Shorebird Project people located 200 in the entire area (along with 2000 Semi-palmated Sandpipers of which I saw fewer than 100, 1500 Ruddy Turnstones of which I saw about 500 and 20 Sanderlings, of which I saw 11). There were also 8 Willets and about 200 Laughing Gulls and some 100 Dunlin in two flocks, one of which on the mudflats where the road curbs along the shore (these were not mentioned by the Project). It was low tide and although one day before the full moon, there were hardly any crabs along the road, which was surprising because two weeks earlier there were about 100 crabs trying to find a beach. While the shorebirds feed on fresh eggs before they fly on to the Arctic, not all the remaining eggs hatch in the summer, some take several months and so we saw in late September 2009 a flock of about 50 Turnstones and 20 Sanderlings feeding in the “May mode” on a rare clean patch of gravelly beach at Port Mahon.
Away from the beaches, especially at high tides, large numbers of shorebirds may gather to roost in impoundments, as was the case on April 20, 2012 at Bombay Hook (Del.) when I estimated the various separate groups of a few hundred at more than 2,000 all together; a flock of less than 100 Black-bellied Plovers was off by itself on dry mud in Bear Swamp, but in the other pools three groups of Dunlin contained also quite a few Short-billed Dowitchers, Lesser Yellow Legs and some smaller peeps, but two flocks, one of them of several hundred, of Semi-palmated Sandpipers were off by themselves. The size of these flocks looked most impressive when they all wheeled about in the air as a Harrier tried its luck. During the next two weeks the Del.RBA still mentioned thousands of shorebirds there. On May 18, at low tide several thousand actively foraging birds were mostly spread out on the mudflats across from Shearness including hundreds of Black-bellied Plover and Dunlin; as expected for mudflats, there were no horseshoe crabs in evidence. For the week of 4/25/12 the Del. Rba reported 7,000 Knots, 5,000 Dunlin, 10,000 Semi-Palms, 1,000 Sanderling and 2,000 Sh-billed Dow., at Mispillion; at the Ted Harvey area there were 2,500 Knots, 3,800 Dunlin, 6,000 Semi-palms, 2,500 Sh-billed Dow. This adds up to 40,300 shorebirds (Ruddy Turnstones or other shorebirds were not included in the reports from either place). The Delaware Shorebird Project, noting on 5/29 that shorebird numbers were greatly diminished, reported for Mispillion 50 to100 Knots, 2,000 Ruddy Turnstones, 1,500 Sanderling, 14,000 Semi-palms and small numbers of Dunlin and Sh-billed Dowitchers. We were along Rte 9 and Bombay Hook, not at any beach, on 5/31 at low tide and saw about 750 Semi-palms spread out over the mud (flying in small separate flocks of about 50 when moving), 2 Black-bellied and 3 Semi-palmated Plovers, 1 White-Rumped Sandp., and perhaps 20 Dunlin. Although the crabs prefer gravelly sandy beaches to lay their eggs, once again we scoped the mudflats that were open to the Delaware Bay and found no evidence of Horsehoe Crabs (and never any Knots). Thus while tens of thousands of shorebirds stop over on the Bay, most do not depend on the crab eggs and large numbers clearly do not feed near the "horseshoe beaches."
In 2014, Colette and I spent May 19-21 in N.J. and Delaware. We started with the Forsythe NWR which after super storm Sandy has a larger sandy stretch along the Southern dike, but we saw few crabs and no Knots. It was low tide and were 100s of Semi-palmated Sandpipers, some twenty Turnstones, a few Dowitchers were foraging in the mud and shallow channels, while the Dunlin were mostly in the impoundment along the North dike. By the time we got to Nummy Island it was high tide and shorebirds were hard to find in the tall saltmarsh grass that was high enough to hide a foraging Tri-colored heron when it stepped into a channel. The next day we stopped off at Reed's Beach where on the southern beach there were plenty of crabs, a few thousand Laughing Gulls and lots of shorebirds, including Knots. But even at 60x the clustered shorebirds were difficult to keep apart. At the North end, there were also lots of crabs, but only 3 Knots among the hundreds of Gulls. In the afternoon we had more success at Cook Beach (which is below Reed's) where the fence is closer to the shorebird roost. But the best views we had the next day at Mispillion, on the Delaware side. According to one of the researcher Colette talked with there were some 1500 Knots roosting on several sand spits and the jetty and thousands of such other shorebirds as Turnstones, Dunlin, Sanderlin and Semi-palmated sandpipers as well as the ever present Laughing Gulls. We did not visit any of the other Delaware Bay beaches, but at Bombay Hook there were a larger numbers of Semi-palms and Dowitchers on the mudflats.
To me, this kind of evidence is among the most spellbinding as it raises questions about the rhythm of nature, the life of birds, the timing of their migration, the choice of the Delaware Bay rather than some other place where there also are horseshoe crabs, or what will happen if the crabs, these fossils of earlier stages of evolution, really disappeared. Current studies are mostly focused on the taking of the crabs for bait by eel and conch fishermen or for medical research which uses their blood since it was discovered, in 1956, that the crabs have an inbuilt blood-clotting mechanism which acts like a primitive immune system. These crabs have a 90% survival rate when they are returned to the sea (Post "LAL Research" on udel.edu). A "soundbite" item in the Nat. Geographic Mag. for August 2011, pp 28-29, states that 500,000 crabs are caught each year along the US coast, They take 20% of the blood of each crab, after which they are returned to the ocean where they have a 15% survival rate, which means that 75,000 don't make it. A post (2 Febr.,’03) on the Delaware Audubon website painted a dismal picture: from an estimated 80,000 Knots on the Bay in 1998, the number fell to about 30,000 in 2002 and the Knot was thought to have a 54% survival rate [for the Bay population?]. In the post "Shorebird Recovery Project" at Manomet.org [2008?] it is estimated that the Red Knot "will become extinct by 2010." As reported in the NYT article cited earlier, this fortunately has not happened and the Manomet post should have been updated. A 2012 post at Manomet.org (Shorebird Recovery) giving a graph of the decline for several species states that the Knot population declined to 15,000 from 50.000 in 1985. Somehow the numbers do not appear to add up.
Such declines may seem hard to believe and since the Morrison article, more research has been done on the accuracy of counting birds by European ornithologists. They found that the average error for flocks of roosting birds was 37% and 17% for flying flocks. Status 2007 makes it clear that recent counters, incl. Morrison himself, are fully aware of these possible errors. (37% or 1/3 of 150,000 equals 50,000 or the alleged total of 1985). Some annual fluctuations in the numbers cannot be explained by counting errors; other explanations are unfortunately still hypothetical. Aerial counting has the further disadvantage that small wader species are difficult to identify, though on the Bay the larger size of the Knots may help. Still, even if the Delaware Bay figures are only approximate but show a long term trend they are alarming indeed and crab conservation measures may be coming too late, partly because crabs take about eight or more years to reach the egg laying stage.
Obviously there remains a lingering confusion about the actual numbers. Apparently researchers, writers, much less reporters, do not spend much effort in weeding out the received data from later and more accurate ones. I have given sone examples above, but here is another one from Birdlife International (2010) whose www.Birdlife.org/datazone/sowb/casestudy/23 on the impact of shellfisheries states that at one time there were 150,000-100,000 and "now as few as 18,000" Knots while referring to Status 2007 (for the later number?).
As I indicated, we don’t have horseshoe crabs in Holland and thousands of Knots (both the Canutus and Islandica subspecies) feed in the Wadden Sea area on small cockles. Over-harvesting of cockles, it is thought, caused the drastic decline in the number of the nominate Knots, but not as much of the Islandica subspecies that feed on the same prey. This may be because the nominate species (from the Eurasian tundra) arrive after the Islandica (from Greenland and Canada) and thus find fewer prey. The destruction of cockle beds in the Wadden Sea resulted from fishing with suction dredges which increased the yield of cockles some forty times to 80,000 tons in 1989 over the older trawling methods. This type of fishing was outlawed in 2004, but by then the damage was done. Similar shellfish harvesting problems existed on the Wash. Considering that there are many other small prey like Baltic tellins, sand gapers and so forth in the Wadden Sea, I wonder why the disappearance of one shellfish could have such a drastic effect, unless the dredging disturbed the bottom habitat for these other prey as well.
I have also wondered whether rufa Knots could switch to another source of food. The rufa that winter in Patagonia, like other long-distance migrants (for ex. Bar-tailed Godwits and the canutus Knots in Europe), undergo physiological changes to reduce their weight before they undertake their northward flight. Among these is a change in their digestive system which prevents the Rufa from feeding on mollusks and makes it convenient for them that there are crab eggs. It would take extra time for the digestive system to change back, up to six days, before they could use the other food on which Dunlin etc. forage. It is argued that the birds need to regain the body weight they lost during the flight from the wintering grounds and a delay needed to change the digestive system would retard their return to the Arctic where there is only a short window to breed. Of the six populations of Knots only the Rufa has come to rely on the horseshoe crab. There is, nevertheless, important evidence provided by research done on the Virginia barrier islands, where some 13,000 Knots feed on the way north and that are apparently not dependent on the horseshoe crab (F.M. Smith and others, 2008); a summary of which is an addendum to Update 2010. Status 2007 (2008) discusses the Va counts in detail, going back to the late '70s - the era of high counts - when on May 20, 1978, 8,000 were counted on Metompkin Island alone. Their more recent numbers are larger than that of the alleged Roselaari populations that winter in northern Brazil or Florida and that might move up the coast in Spring; thus these Virginia Knots are likely to be Rufa. I have not found evidence for my suspicion that Virginia's Knot numbers are used to justify its opposition to the ASMFC harvest thresholds of the crabs. There is also some evidence that Knots from Caribbean areas may use the interior (and crabless) flyway from Texas to Saskatchewan. This may be corroborated by John Krider who in his [hunting] Notes (1879) states that they stop "for a day or two in Iowa, feeding along the slough."
I was interested to read in Clay and Pat Sutton’s Birds and Birding at Cape May (2008), a book that I much enjoyed, that in the late 19th century horseshoe crabs (in the Delaware bay?) had also been faced with extinction. They were nearly fished out of existence for fertilizer and it took many decades for the survivors to repopulate the Delaware Bay. In all my reading on the alarming state of the Bay, I found no reference to that kind of depletion of the crabs other than the fact that by the middle of the 20th century, when the crab population nearly collapsed, artificial fertilizers and other changes in agriculture reduced the need for the crabs (just as it reduced the use of alewives as fertilizer in New England). In the post "Fertilizer" (udel.edu) one learns that the number of crabs remained at about 1.5 million from the 1880s to the 1920s. The post "Regulations" on udel.edu cites a report that in 1857 the "entire strand of beach" was covered for miles with the crabs and it shows a foto from the early 1980s illustrating a similar event. Recently, as I hobbled down the stairs to the bathroom in a Lewes, Del., restaurant I noticed a black and white photograph among the historical pictures on the walls of a gigantic pile of Horse-shoe crab shells: unexpected evidence of their overfishing. Apparently between 1960 and 1980 their number was relatively constant at 2.3 to 4.1 million. Demand for eels from Japan in the 1970s and later for conch, mainly from Sth-east Asia, led to a rapid increase of the crab harvest in the 1990s. Fortunately, ASMFC regulations have led to significant reductions in the numbers taken for bait.
Because my mind has been professionally focused on critically examining received theories (in history), several specific questions occurred to me while reading the Suttons' discussion. Among these are: what did the Knots feed on in those allegedly horseshoe-crabless years? Were there great numbers before the overfishing? Did they feed instead on small mollusks like those seen farther south? And by the way: does the physiological change of the stomach occur also before their southward migration or do they then stop to forage more frequently and longer in one place than on their way north because there is no hurry to find a nesting place? The Suttons report also that the absence of old Knot decoys indicates that there may not have been enough Knots for the hunters to bother making them.
In a odd fit of nostalgia for the days of research for my publications (in the History of Ideas), I perused some of the earlier writers (among my own books) that could have been familiar to Witmer Stone, on whose Bird Studies of Old Cape May (1937) the Suttons relied for for much of their historical data. None of these writers mention horseshoe crabs, which may be because they focus on the southbound migration (August-October), all of them blame the near demise of the Knots around 1900 on market hunters “in the old days,” (Nat. Geogr. Book of Birds, 1932). Eaton, (Birds of New York, 1910) says they are more common in the fall [on Long Island] when “they return in large flocks” than in the spring and Forbush, (Birds of Massachusetts and Other New England States, 1925), noting that the Eurasian and American “forms” were recently split [into two populations], says that “in the days of our grandparents [they occurred] on Cape Cod by the thousand” but were rare by 1900. Knight’s 1908 Birds of Maine supports these findings: they are generally uncommon but more numerous in the fall when there are plenty on the mudflats near Calais; they occur between May 24 and June 11 and return from August through September. The greater number in the Fall than the Spring is the reverse of the modern data for the Delaware Bay. Though these older sources talk about the southbound migration for the autumn, beginning in August, the July 5, 2012, Delaware RBA mentioned about 100 Knots. (This fuels my wonder at the rhythm of nature with shorebirds leaving the Bay in the 1st week of June and returning already in the 1st week of July. And they are not all non-breeding adults, for some were "still" in breeding plumage). These early publications all make use of data from the Proceedings of Bird Clubs, Scientific Societies and Reports from the various Boards of Agriculture. A note in the Jnl of the Maine Ornithological Society (1900:54-55) also bewails the "empty beaches." Stone in 1937, appears to rely almost exclusively on hunting lore. Through his leading career at the Philadelphia Academy of Science, etc. Stone could have had access to any number of 19th century sources . For ex. I wonder what lies hidden in the archives of the New Jersey Division of Fish and Wildlife, that go back to 1870 (www.state.nj.us/fgw/history.htm).
Stone says “as they [Dowitchers and Knots, flocking together] decoyed easily they most nearly approached extermination” at the turn of the century, but suspects the picture may be not be that bleak. This statement may explain why there are no old specific knot decoys, a generic large shorebird one may have done the job. Moreover, 19th Cent. sources often refer to the Knot's unwary behavior so that decoys may not have been necessary. Stone too concentrates on the southbound migration (which may be the result of his mostly summer observations and the hunters he then talked too) and he focuses on the Atlantic beaches and adjacent marshlands. Though he also observed them feeding in May, neither he nor Charles Urner, his correspondent for the Brigantine beach to the north mention horse shoe crabs; the numbers they give are only in the hundreds. The authors cited above describe their food as mollusks, crustaceans, sea-worms and insects which may be less the result of observation than of stomach content of shot birds in the autumn, for in the 19th century much attention was given to the question of a bird's usefulness to combat the generally held view of birds as pests. I wonder whether the pothunters were at it all year or whether they concentrated on the fall migration when numbers were large and farming tasks fewer. I am thinking about the British game law of 1831 that set hunting seasons for game birds from August through January.
A colleague and friend who collects prints drew my attention to Alexander Wilson whose American Ornithology is a pioneering work, much of which can be retrieved on the internet. In the 1840, 3 vol. edition by Thomas Mayo Brewer "with notes by [Sir William] Jardine," (the Scottish naturalist) a later editor wrote: "of this prettily marked species I can find no description . . . The common name on our seacoast is the Gray Back . . . [and it occurs] in small flocks on the sand flats." This is followed by a description of the Red-breasted Snipe, i.e. the Dowitcher. But in Alexander Wilson. The Scot Who Founder American Ornithology, (2013), the authors cite (pp 182-4) two descriptions of the knot, one the "Ash-colored Sandpiper, Tringa cinerea," which is the Knot in winter dress and the other the "Red-breasted Sandpiper, Tringa rufa" for the Knot in breeding plumage. . . . its favorite food, which is the small, thin, oval, bivalve shell fish of white or pearl color, and not larger than the seed of an apple.[which] must be extremely nutritious, for almost all those tribes [of sandpipers?] that feed on them are at this season [May] mere lumps of fat." I wonder whether these small white pearls were really shell fish rather than the eggs of the horse shoe crab. But in his description of the Ruddy Turnstone, which he calls a "rare species," Wilson mentions that in Cape May and Egg Harbor they are "known by the name of the Horse-foot Snipe from its living almost entirely on the eggs" of the crab, which is in fact what Knots do as well. It is likely that the "gunners" whom he mentions sometimes as sources, may have given him anecdotal information, which seems to indicate that it came from the ocean rather than the Bay beaches.
In the 19th century "Snipe" was a frequently used name for shorebirds especially for those with long beaks. Not only was the Knot known as Robin-Snipe, but Shriner in his Birds of New Jersey (1896) also gives the name "Gray Snipe" and on p. 139 lists seven non-snipes, including Stone Snipe (Yellow Legs), Winter Snipe (Dunlin) and Grass Snipe (Pectoral Sandpiper) though the last two do not have particularly long beaks. Of the Knot he says (p.94) "it has been killed off to a great extent, proving an easy prey for pothunters" and also adds "it feeds on small shell-fish along the beaches," which is does in the Fall. In 1869, William Turnbull published a list of Birds of Eastern Pennsylvania and New Jersey, in which he gives the following common names for the Knot: "Red-breasted Sandpiper, Robin Snipe, Ash-coloured Sandpiper, Grey Back, White Robin Snipe in its autumn plumage." He says that it is "common" and "arrives in May on its way north, returning about the middle of August." There is no information about its feeding habits.
Considering the difficulty of traveling in Sth. Jersey before the automobile – Stone talks of days with walks of 10 or more miles - the Delaware Bay was apparently neglected by birding summer residents who preferred the then still mostly unspoiled beaches of the barrier "islands." Horseshoe crabs prefer rough sand beaches and quiet shores over the surf beaten Atlantic coasts. All this information coincides with the numerous maps of "Critical Habitat" in the back of the Status 2007 report that are based on recent surveys. Clearly reflecting the interests of the New jersey Division of Fish and Wildlife for which the report was put together, there are two maps for the Delaware Bay region, one for the Spring and one for the Fall Migrations (## 19-20), the latter showing more critical habitat on the Atlantic beaches. Map #17 shows the habitat for Virginia, one long stretch from Assateague to Fisherman Island, nearly all of it on the Ocean side with a relatively small area on the Chesapeake Bay.
Because I once thought about collecting decoys, I looked into the question raised by the Suttons and Stone's remark. Evidently late 19th century shorebird decoys (unlike duck decoys) are mostly primitive carvings that may disappoint someone who has seen decoys from 1950 and later that increasingly developed into what the trade calls "decorative." These can be exquisite works of craftsmanship, painted with great attention to actual plumage. Antique decoys, their original paint flaked off, look more two-tone and even uniformly dark. The actual shape and size of a shorebird species clearly was not one of the carver's criteria even in the so-called "elegant" type. One catalogue (Old Decoys, from Cary Campbell) has a Black-bellied plover "painted over as a robin snipe" (the folk name for Knot) now looking just dark. It also shows a "dowitcher or yellow legs" of 9.5" in a 2-tone grey; a 10.25" robin snipe, also 2-tone with reddish below and an 11" turnstone "perhaps from Cape May" of which the remaining paint barely imitate the colors of an actual Turnstone. It also has a 13.5" Crowe carved decoy, uniformly dark, from N.J. "very much like shorebirds from the area," which has a broad beak and thus might be modelled on a Knot which has a heavy beak. The Sedge Island Decoys Antiques catalog features a small robin snipe,very dark, with a short bill, with shot marks, as "from South Jersey." The Dayton's on-line catalogue of Nov.2011 has a "black bellied plover, about 1900. from Tuckerton, N.J. with original paint." It's all black underneath and very dark above with some lighter spots imitating a shorebird's back; it's a plover in name only. The current Raven's Way Antiques website in describing a Shute (Cape May Courthouse) carved Blackbellied Plover (1870-1900) says that few Shute decoys have come to market incl. "a couple of Red Knots." The site also shows a 9" robin snipe from Chincoteague, early 20th cent., that is dark above, dark red on throat and breast with off-white to the tail, the bill is longer than a Knot's. There's also a picture of a Rio Grande, N.J. "plover" that's uniformly dark brown with black "feathering" spots, 8.5" and it has an unploverish plump body. All this suggests that around 1900 hunting shorebird decoys were not very species precise and apparently interchangeable all along the East coast, incl. Sth. Jersey.
One of the sources I also looked at was Cassinia, the organ of the Delaware Valley Ornithological Club, of which Stone had been an editor as well as a club member from its very beginning. Some of its articles give a good impression of the pre-automobile difficulties of birding. For example, the 1903 Christmas count at Cape May Point was done on foot (some participants had no binoculars or only 3 and 4 power ones, i.e. "opera glasses"). J. Fletcher Street (l931/2) writes that the car made all the difference as day trips to the Jersey shore became possible (though even now, with more and better roads my own day trips involve fours of back and forth). Most early field trips, he writes, were to areas around Philadelphia and those to the shore did not begin until the 1920s. Street recounts that Stone, in 1918 or so, ventured the opinion that all but 2 or 3 of a group of members knew nothing concerning shorebirds, a remark that spurred Street on to remedy his shortcomings. Having acquired a cottage on Sea Island, NJ, (i.e. also on the Atlantic rather than on the Delaware Bay) he kept a record of the birds there, a ten year summary of which he published that year; of the Knots he says that they are much commoner (but not in great numbers) in the Spring than in the Fall, but nothing at all about feeding habits. In the 1951 issue these observations are confirmed, but again there's nothing about feeding habits. By then the hunting pressures of the past had been absent for decades and one would have expected reports of larger numbers. In the on-line Indexes to the journal there's also no mention of the horseshoe crab. The general impression gained from the pre-1950 on-line articles is that the DVOC was club of gentlemen from various backgrounds who gradually changed their collecting of skins and eggs (about which there are several stories in the earliest issues) to exchanging mostly random observations. Stone deserves praise for recording these, together with his own, more systematically for Cape May).
At the occasion of Biodiversity Day 2007 the U.N’s World Conservation Monitoring Centre issued a news release on the status of the world population of all six populations of Knots, four of which are declining in numbers. In Europe and the USA the cause is thought to be “drastic habitat changes in the major mudflats” but a significant part of the release discusses the disappearance of large snow free patches in the Arctic breeding ranges, a probable result of global warming which increases precipitation that falls there as snow. In spite of these declines the worldwide status of the Knot is listed as of "least concern." Yet, a release, issued by the Convention on Migratory Species of 8-16-07 reveals that major losses of Knots occurred near the border of Uruguay and Brazil (a place that does not occur in the discussions on Knot migration that I have read), the causes of which are under investigation.
The threat to the rufa Knots has been dramatized in a 2008 documentary that did the rounds on PBS’ Nature series (it was also seen in some European countries). Another question suggested by that documentary is whether it is only the convenient availability of the crabs’ presence in the Bay that makes it the eel's and especially the conch's allegedly preferred food. After all, what did fishermen use for bait before the 1990s when the increased harvest began or in months, before the crabs come to shore or after the surviving crabs returned to the ocean? From my childhood experience, including the catch of our neighbor the fisherman, I know that eels feed on virtually anything, including carcasses of mammals and I think that offal from the chicken slaughter around the Bay would be much appreciated by the eels and conches. I also wonder whether egg bearing female crabs are really more useful than males. There's a good deal of evidence that eels feed on the eggs of alewives and the like (which they suck out) when these move upstream to spawn, in fact it is well known that eel prefer live bait and eel farmers have to accustom elvers to eat their food and the loss of elvers is fairly large during that process. But in the wild fish and crab eggs are "opportunistic" foods. Delaware has a regulation of one half female and one whole male per eel/whelk pot, which indicates that the eggs are not an indispensable food. This I wonder why the many crabs that die after spawning or are turned on their back by wave motions littering the beaches cannot be collected for bait. Perhaps conches that feed normally on clams (and other mollusks) need to have a food supplement because the natural food has declined in the polluted Bay.
As a result of its t.v. time restrictions the PBS documentary focuses too much on the horseshoe crab and the rufa Knots of the Delaware Bay. Carl Safina, The View From Lazy Point, 2011), described how he and an acquaintance attempted to protect horseshoe crabs on Long Island from being taken [probably to be sold to Delaware Bay fishermen]. I have seen dead crabs in many places along the Atlantic coast, for example near Nausett on Cape Cod and even as far inland as the Salt Bay above Damariscotta in Maine where they have to go under the traffic bridge. And Rachel Carson (Edge of the Sea) states that the crab occurs from the Yucatan to new England. Interestingly, Paul Brooks (The House of Life, p.152) relates that the idea for Carson's book may have originated during a walk on Cape Cod by "distinguished literary figures [. . .] somewhat lacking in biological sophistication" who saw the beach covered with horseshoe crabs which they began to return to the sea. A Houghton Mifflin editor who was among them then thought about finding an author who could write "a layman's handbook to the shore."
Anyway, in accordance with the new population research method of counting birds on their winter and summer territories, the film shows the searchers camping out in Tierra del Fuego where the numbers have declined, and on the arctic tundra looking in vain for breeding birds. I have not seen much tundra and that only in Alaska, but have the feeling that a presumed 15,000 pairs of Knots can completely disappear in the vast expanses, a problem that is discussed in Status 2007. Telemetric data (obtained, of course, from a very small number of outfitted birds) give a good illustration of the very wide breeding territory, anywhere from about the 60th to 68th parallel and from the 62th to the 100th degree longitude (fig. 11, p.19). Yet, considering the well established fact of “site fidelity” in many breeding birds, the expectation is that Knots would return to their territories year after year. (Ec.atlas, p. 303). Their absence could be significant evidence of their decline unless the returning birds, finding conditions altered move to more suitable nesting sites, "territorial fidelity" in knots not having been definitely established. Piersma and Lindstrom (cited below) assume that relocation to suitable sites would be normal.
The documentary focuses also on the here and now and as such brings to the attention of a wide public how the fortunes of the crab and the Knot are (have become?) intertwined and affected by human actions e.g. a 2012 post on Manomet.org "Red Knot Protection in Southern Argentina," has examples of promoting more responsible recreational use of the coastal areas where the Knots winter). As would be expected the two Status Reports are more balanced and often discuss the disparities in the data, in particular the divergence in earlier estimates. The authors of Status 2007 (which was published, with an earlier update, in 2008 as #36 of Studies in Avian Biology), present their findings with great scientific integrity. They even address whether their own scientific investigations may pose a threat to the Knots. Such qualifiers as "estimate," "conjecture" and acknowledgements that further research is needed are frequent. Update 2010 "reflects the state of knowledge as of 1 April 2010. . . This material [unlike the 2008 publication] has not been peer-reviewed. We offer it in the interest of timely information exchange among researches, managers and others interested in Red Knot conservation." These statements can of course be used by skeptics to minimize the crisis and a reader of funding proposals may dismiss the "need for further research" as a plea for continued employment of the researchers.. I would say so far, so good. The 2008 recommendations, rather modestly, focus on the conservation of current numbers and habitat improvement. These objectives are significantly at odds with the goals set in the "Executive Summary" of Status 2007 (p.iv) where the goals for 2015[!] are based on the figures of 25 years ago although these have since been corrected downwards. All this does not mean that conservation measures are not warranted, both for the horse crab and the rufa Knot; for ex.: following Canada's example of according the rufa Knot "threatened" status seems a given.
But it still appears to me that a thorough and systematic study of historical evidence, however dispersed, would be useful either for establishing that present developments are less critical because the crabs as well as the Knots have recovered before (thus forestalling the skeptics) or for making the alarm of the environmentalists still more justified. Additionally there remains the decline of the other populations of Knots in other parts of the world (and of other shorebirds, e.g. the almost total disappearance of Red-necked Phalaropes on the Lubec Flats, Me. since the 1990s) which may point to other (man-made?) environmental factors. Numerous studies have been published on the decline of shorebirds. Among these I found Christoph Zockler, et. al. "Wader Populations are declining- how will we elucidate the reasons?" Wader Study Group Bulletin, (2003), 100:202-211, the most balanced. Of the 209 species of waders 92 showed a declining trend of which 79 are among plovers and sandpipers. They concentrate on the gaps in our knowledge about the reasons for that trend. Perhaps the Knot could be treated as the proverbial canary in the mine or the rose at the head of a row of vines, and its decline taken as a warning of the accumulating effect of global environmental degradation (Piersma and Lindstrom. "Migrating shorebirds as integrative sentinels of global environmental change," Ibis (2004), 146 , Suppl.1, 61-69). The relationship between the Horse-show Crab and the Red Knot is well studied but the factors that affect other Knot and shorebird populations may also (additionally) affect the Red Knot.
Meanwhile the Delaware Public Radio station WDDE aired an interview with Kevin Kalish of the Delaware Division of Fish and Wildlife in which the old numbers do not appear. Instead it's about the alarm caused by the "crash" numbers of 15,000-20,000 and the 2012 estimate of 44,000. Kalish was cautiously optimistic "that there is no extinction risk in the next few years. We have at least stabilized the population." (www.wdde.org/45004, June 1, 2013). However, on May 30 the Manomet Center for Conservation Science posted a newsletter about the resighting of Knot B95 at Mispillion and in the companion article said that the expected number of Knots was 28,000, the same as in 2012. Thus there's a disparity which would be a reason to be less optimistic about the recovery than the number of 44.000.
With apologies to Jonathan Swift as well as Steve Kress, I offer a modest proposal that may help increase the Horse-shoe crab eggs available to the Red Knot. In order to restore the tern populations
at the same time as that of the Puffin, one of the techniques was to turn (and shaking) the eggs of the gulls whose populations had exploded as a result of the open garbage hills of coastal tons in Maine. This markedly reduced the gull population that preyed on the eggs of terns and their hatchlings. A similar program along the Delaware Bay would help reduce the population of Laughing gulls that seem to me to be the major consumer of the crab eggs.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment