Indirect effects of lemming cycles on sandpiper dynamics: 50 years of counts from southern Sweden

Abstract

The bird-lemming hypothesis postulates that breeding success of tundra-nesting geese and waders in Siberia follows the cyclic pattern of lemming populations, as a result of predators switching from lemmings to birds when the lemming population crashes. We present 50 years of data on constant-effort catches of red knot Calidris canutus and curlew sandpiper C. ferruginea at an autumn migratory stopover site (Ottenby) at the Baltic Sea, supplemented with literature data on winter censuses of dark-bellied brent goose Branta b. bernicla and white-fronted goose Anser albifrons in northwestern Europe, and waders in Germany and Southern Africa. Number and proportion of juveniles in these bird populations (both our own and literature data) were compared with an index of predation pressure (calculated from the abundance of lemmings on the Taimyr peninsula), and climate indices for the North Eurasia and the North Atlantic regions. The index of predation pressure correlated significantly with the number of juveniles of red knot and curlew sandpiper, but not with number of adults. Also, this index correlated with the reproductive performance of geese and waders reported in the literature. Fourier analysis revealed a significant deviation from random noise with the maximum spectral density at the period length of 3 years for number of juvenile red knots and curlew sandpipers captured at Ottenby, abundance of lemmings, reproduction in arctic fox Alopex lagopus, and reproductive performance in geese on the Siberian tundra. Also, the date of passage at Ottenby for adult red knot and curlew sandpiper showed a spectral density peak at a period length of 3 years, the latter species also showing a peak at a period length of 5-6 years. Passage dates for adult red knot and curlew sandpiper were earlier in years of high predation pressure compared with years of low predation pressure. The fluctuations in reproductive success of the studied Siberian goose and wader species appear to be primarily influenced by biotic factors in the breeding area, rather than by abiotic factors, such as climate oscillations. Annual variations in migratory arctic bird populations may have far reaching effects in habitats along their migration routes and in their wintering areas. We suggest a link between lemming cyclicity in the Northern Hemisphere and predation pressure on Southern Hemisphere benthos, in which the signal is carried between continents by long distance migrating waders.

Variation in Timing of the Siberian KnotCalidris c. canutusAutumn Migration in the Puck Bay Region (Southern Baltic)

“…It is well known that the breeding success of Siberian Knot follows in average a three-year cycle, with the high production of young in years of high lemming abundance (Underhill 1987, Blomqvist et al 2002. During this study the changes of juvenile number in subsequent seasons were not regular.…”

“…These two Knot subspecies come from remote breeding areas and their breeding success is influenced by different factors. Only data from Helgoland given by Blomqvist et al (2002) concern the canutus subspecies (Dierschke 1994). The highest number of juvenile Knots between 1988 and 1994 were ringed in 1990 and 1991, which is consistent with the results of counts in the Puck Bay (see Fig.…”

Migration and morphometrics of Temminck's StintCalidris temminckiiat Ottenby, southern Sweden

“…This is a similar difference as in the Knot (22 days), but shorter than in the Curlew Sandpiper (33 days; Blomqvist et al 2002). The time difference means that juveniles are usually not accompanied by adults from their own breeding population, and they probably have to rely on an innate migration program to direct them to the population-specific wintering grounds.…”

“…The Knot and Sanderling, with the latest spring passage, are destined for the breeding areas furthest away from Ottenby, situated on the Taymyr Peninsula and further east (Lappo 1998). Hence, it seems that distance to the breeding The autumn median passage of adult Temminck's Stints (28 July) was only a day earlier than that of adult Curlew Sandpipers (29 July), while the median passage of Knots is 9 August (cf Blomqvist et al 2002). The juvenile passage was, however, 11 days earlier in the Temminck's Stint than in the Curlew Sandpiper and the Knot (both species median date 31 August, Blomqvist et al 2002).…”

“…Hence, it seems that distance to the breeding The autumn median passage of adult Temminck's Stints (28 July) was only a day earlier than that of adult Curlew Sandpipers (29 July), while the median passage of Knots is 9 August (cf Blomqvist et al 2002). The juvenile passage was, however, 11 days earlier in the Temminck's Stint than in the Curlew Sandpiper and the Knot (both species median date 31 August, Blomqvist et al 2002). This difference in timing probably reflects longer distances between their breeding ranges and Ottenby of the Curlew Sandpiper and particularly the Knot.…”