I have already suggested that extraterrestrial events, particularly the 11-year sunspot cycle, are increasingly believed to influence the atmosphere of this planet. The Chinese and Japanese have remarkably precise records of the northern limits of certain agricultural crops at particular times, the phenology of flowering, and the freezing of lakes. These demonstrate long-term trends in overall climate in eastern Asia that extend over hundreds of years. The climate of Japan is influenced by the high-pressure area in winter over mainland East Asia. There is evidence that severe ice conditions in the Bering Sea during the early 1970's may have been due to an eastward shifting of this high-pressure area. Again, the water mass of the Kuroshio Extension and the West Wind Drift takes several years to travel across the Pacific Ocean, and there is an established temperature variation that travels like a slow wave with it. Off Japan, the Kuroshio Current periodically develops meanders which slow the speed of the eastward flow. Cold and warm "pools" of water approach the west coast of Canada and the western United States from time to time.
Ocean currents are driven by the atmospheric motion above them, which consists of several convective cells between the equator and each pole. The outcome is zonal winds, such as the trade winds and the westerlies. However, as the influence of the sun on the atmosphere is variable, the input of heat and the extent of the major high-pressure areas vary, as does the path of the jet stream. The recent droughts in northern Africa and unusually heavy rains in Australia are both linked to a southward shift of the Intertropical Convergence Zone in the atmosphere and a "corrugation" of the wind circulation from a more normal zonal (latitudinal) path. These shifts in the atmospheric circulation are almost certainly transmitted also to the ocean currents and the marine ecosystem, with the influence being felt for a long period of years.
One of the oceanic domains of the North Pacific is the transitional domain, which lies east-west where the West Wind Drift impinges upon the coasts of British Columbia and Washington State. It is precisely in this sector that there was a well-documented "temperature anomaly" in 1957-58. Since an anomaly implies something completely out of the ordinary, I seriously question the appropriateness of the term for an event that may or may not be recurrent (at the time it was a pronounced variation from the oceanographic records accumulated up to that time, but the period had not been a very long one). It is no coincidence that the numbers of albatrosses recorded at Ocean Weather Station "Papa" was higher during this warm-water "anomaly" than subsequently (indeed, an 18-year record of the seabirds recorded at "Papa" also exhibits other interesting fluctuations from the base-line data in certain years).
Recent analyses of sediments from off the coast of California have demonstrated long-term fluctuations in sardine populations extending back at least 1,800 years, with increases lasting 20-150 years and spaced 20-200 years apart. The number of anchovies declined steadily. Yet until now, El Niño events have been treated as anomalies in that region as well as off the coast of Peru. Just as we recognize that different species of fish follow the warm water north on such occasions, we must also recognize the rather distinct seabird species assemblage that is trapped, as it were, in the Gulf of California. Clearly, like the termination point of the West Wind Drift at about the 45-55° parallel, the coast of Baja California and southern California State, from the 25-35° parallel where the California Current begins to swing away from the coast to the west as the North Equatorial Current, is another zone of instability.
I think that it is no accident that the southern limit of several northern species of North Pacific seabirds ends in southeastern Alaska or northern British Columbia, and that the northern limit of the ranges of several other species occurs in Washington State or southern British Columbia. Indeed, the west coast of Vancouver Island is not rich in species, and several of those that exist are not present in great numbers. This is a region of rather more variable conditions than elsewhere, and species evidently find that it is difficult to colonize and it quickly becomes unsuitable again. Since 1940, indeed, there has been a parallel decline in the annual mean sea-surface temperature at a number of coastal recording stations in British Columbia, and this seems to have been a rebound from a less well-documented rise in sea-surface temperatures during the 20 years before that, which culminated in a peak around 1940. Salinity has likewise trended downwards during the last 30 years. The seabird colony size data before 1960 are so nonquantitative that it is impossible to be sure what changes in seabird populations and breeding sites may have taken place in response to these physical changes.
The lesson is that we must now examine all future census and distribution data with trends in sea-surface temperature and salinity in mind as two of several likely factors influencing them. We must no more ignore data outside our own field than a salmon ecologist might.
Conclusions
We know little of the accuracy of censuses of seabird numbers made between 1850 and 1950. There has been a tendency to assume that numbers of seabirds at long-established colonies have been relatively unchanging, even though the expansion of some species into previously unrecorded breeding sites in low numbers is well documented. Contraction of breeding ranges, likewise, has most commonly been attributed to the influence of man. Recent literature from the physical sciences, on the contrary, suggests that seabird numbers at particular colonies are most unlikely to have been stable for any great length of time, at least at high or middle latitudes and particularly at points where boundaries between currents impinge on continental coasts. Indeed, some early estimates of colony sizes may not have been as much in error as we may have assumed, neither when apparently too large nor when apparently unlocated by previous visitors.
The halving of a large colony over a period of 20 to 50 years in the middle of the range of a species and the establishment and disappearance of smaller breeding groups at opposite extremes of the range (both latitudinally and longitudinally), may equally reflect natural long-term climatic or oceanographic changes and may naturally be reversed at some time in the future, perhaps within half a century. The implication for conservation of seabird colonies that are at the contracting end of a species' range is that cultural rather than biological criteria may be the best determinants.