Greenlandic Peregrines will have normal eggshell thickness by mid 2030’ies

Knud Falk, Søren Møller, Frank Farsø Riget, Peter Borgen Sørensen, Katrin Vorkamp

    Publikation: KonferencebidragPaperForskningpeer review


    Since it was first shown that DDT caused eggshell thinning and breeding failure in wild peregrine falcon (Falco peregrinus) populations, the effects on the eggshell thickness and breeding success in high-trophic level birds have been widely documented. Studies of peregrines and ospreys (Pandion haliaetus) in Europe have documented that it took 30 years from DDT was phased out
    until eggshell thickness was back to normal pre-DDT levels.
    In Greenland, the peregrine population has been the subject of long-term studies, and a previous study of eggshell thinning found a significant increase over time (1972-2003) in thickness of eggshell fragments from West and South Greenland. As part of ongoing updates of a previous comprehensive analysis of persistent organic pollutants in peregrine eggs from South Greenland, now covering 1986-2014, we extended the time series for eggshell measurements and reinterpreted data for a 43 year time span. Mean shell thickness was estimated for 184 clutches based on fragments from hatched eggs, and for 56 whole addled eggs from 44 clutches. During the period 1972-2014 there was a highly significant increasing trend in the average eggshell thickness of 0.25% per year. This corresponds to a change in eggshell thinning from 13.9% to 3.4%
    in 2014 when compared to pre-DDT eggs collected in Greenland. With the current rate of change, a “normal”, pre-DDT shell thickness is predicted to be reached around year 2034. However, a few clutches are still below the critical limit. The slower recovery of the shell thickness in the Greenland population as compared to other studies is likely indicative of the slower phasing out of DDT in the Greenlandic peregrine’s wintering grounds in Latin America. The shell thinning in the Greenlandic population crossed the 17% “danger limit” associated with population declines probably only for a few years, if ever, contrary to the populations of the same subspecies in Arctic Canada and Alaska. The long-term sampling of eggshell fragments allowed us to verify that the peregrine population in Greenland is responding to the gradually reduced exposure to shell-thinning substances. Principal component analyses of effects on shell thickness of a wide range of persistent organic pollutants measured in the eggs disclose how some of the tested compounds had a correlation with shell thickness, where the effect of DDT and its degradation products dominates over the effect of other substances. These results show that continued measurements of shell thinning serve as a low-cost proxy for monitoring environmental loads of the DDT compounds.
    Publikationsdatosep. 2017
    Antal sider1
    StatusUdgivet - sep. 2017
    Begivenhed4th International Peregrine Conference - Herman Otto Institute, Budapest, Ungarn
    Varighed: 27 sep. 20171 okt. 2017
    Konferencens nummer: 4


    Konference4th International Peregrine Conference
    LokationHerman Otto Institute
    AndetThe Peregrine Falcon Falco peregrinus is an icon of success in nature conservation.<br/><br/>In many countries Peregrine populations are in favourable conservation status, even better than before the major declines that occurred in the 1960s and 1970s. In many countries there are ongoing projects involving reintroduction and management of the wild populations, in others such projects have now ended successfully. However, there still remains the challenging task to re-establish the tree-nesting population in central Europe.<br/><br/>The organisers of the Budapest Conference have the honour to announce Professor Tom Cade as a member of the Scientific Committee and welcome his generous proposal to count the next year's Conference in line with the Madison (1965), Sacramento (1985) and Poznan (2007) Conferences, making it the 4th International Conference to be dedicated to the Peregrine Falcon.<br/><br/>Peregrine studies are routinely presented at ornithological conferences, but as one of many other issues. This Conference will bring together experts and researchers from around the world to present the extensive range of Peregrine research that has been carried out over the last ten years.<br/><br/>The first such conference took place in 1965 in Madison, and was successful not only in highlighting the effects of organochlorines on Peregrine populations, but also in bringing a diverse audience together with the common purpose of restoring this species' fortunes. As Cade et al. (1988)* state "As the most cosmopolitan naturally-distributed bird in the world, and as a top predator in the global ecosystem, the Peregrine was and is a unique biological monitor of the quality of the world's environments. Long known as the bird of kings, the Peregrine's preeminent position in falconry and its embodiment of nobility in the wild helped rally to the cause of biological conservation an extraordinary array of individuals and organizations." <br/><br/>* "Peregrine falcon populations: their management and recovery", Edited by T.C.Cade, J.H.Enderson, C.G.Thelander and C.M.White, The Peregrine Fund, 1988.<br/><br/>The 1985 Conference in Sacramento, USA, gathered an enormous number (circa 500) specialists from all over the world. They concluded that modern techniques of breeding and reintroduction, together with a ban on DDT, would allow recovery of many Peregrine populations. <br/><br/>A smaller regional conference was held in1994 in Włocławek, Poland (proceedings in Acta Ornithologica, Vol. 30, No 1, 1995, see on the web).<br/><br/>The 2007 Conference in Poland (proceedings published in "Peregrine Falcon populations – status and perspectives in the 21st century", see on the web) confirmed the recovery of many Peregrine populations around the world and positive growth of many others. <br/><br/>Now, a decade after the Poznan Conference, the global status of the Peregrine has improved significantly. And to celebrate the 20th anniversary of the Peregrine returning to breed in Hungary, the 4th International Peregrine Conference is to be held in Budapest.<br/><br/>This Conference offers a unique opportunity for Peregrine enthusiasts from all over the world to meet up to renew old acquaintances, make new friends and exchange knowledge, experience and ideas. It will be an international celebration of this truly spectacular and cosmopolitan bird for prey.<br/>


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