ORI PUBLISHES PAPER - A Historical Review of Our Knowledge of Brown Lemming Population Cycles at Barrow, Alaska: Cycles No More or Never Before

We'd like to announce Denver Holt's most recent published paper in an Animals Special Issue: Rodents: Biology and Ecology publication. 

Simple Summary

Plague-like population outbreaks of lemmings and voles have been known for centuries. And Arctic lemming population outbreaks have been observed since native people lived there. These observations became common knowledge and were verbally passed along from generation to generation. Written records of lemming outbreaks, and an interest by naturalists in why outbreaks occur, date back over a century. As standardized measures to study lemming species were developed, it was clear that outbreaks occurred only periodically (4–6 years), but patterns did emerge. Thus the concept of “cycle” was born. Whether the word “cycle” is the best descriptor or not is debatable. Nonetheless, the modern study of “cycles” began and continues today mostly using snap-trap and grid sampling methods. Both methods have strengths and weaknesses, and which method to use depends on the question(s). After decades of study, answers to what drives “cycles” remain confusing. Food, social strife, predation, disease, and so forth are known to affect outbreaks; however, no single factor appears to drive the “cycles”. Indeed, multiple factors acting independently and collectively appear to drive the outbreaks, which are not true mathematical cycles and are not predictable. Perhaps it is best to describe these “cycles” as population fluctuations that show patterns over time.

Abstract

The literature for brown lemming (Lemmus trimucronatus) and collared lemming (Dicrostonyx groenlandicus) population cycles was revisited from Barrow, Alaska. This review covered observations and research primarily from 1946 to 1974. Much of what we know about brown lemming cycles from North America was derived from these early studies. The data for collared lemming, however, are far less extensive and only a minor part of the historical research at Barrow. Nonetheless, important information was discovered. Collectively, the historical literature is confusing and sometimes contradictory. The time intervals, amplitude, and density of lemming populations from Barrow varied greatly from year to year. For example, in most papers, 1956 was considered a lemming population high, but in a major research paper in 1993, the 1956 data was sometimes included and sometimes deleted because it did not meet an arbitrary mathematical definition of a population high. Qualitative explanations were often used to support the lemming population cycle concept when it was apparently in flux or did not exist. Other investigations suggested synchronous lemming population fluctuations over wide geographic areas did not occur, but rather were localized most of the time. Even within a specific local area, lemming densities varied with habitat. Presumably, higher densities were in higher quality habitats, but this could vary somewhat with season. It is unlikely that lemming migrations occurred; however, local movements of large numbers of lemmings were witnessed. Although many studies suggested a specific event influenced lemming population fluctuations, overall, the data suggest multiple factors acting synergistically drove the x-fold increases and x-fold decreases in lemming populations at Barrow. Other qualitative observations, and quantitative studies suggest lemming population fluctuations affect and have an effect on the survival and reproduction of other species of birds and mammals at Barrow. Brown lemmings should be considered an indicator of the health of the Arctic environment at Barrow. Clearly, population fluctuations of lemmings at Barrow existed with an average interval for peak populations of about 3.8 years, ranging from 2 to 6 years, depending on what data was included and how it was analyzed. The conundrum, however, is defining a peak. Furthermore, one must ask if an average interval between peak lemming populations is really a cycle. The data support population fluctuations; however, the four annual phases of the cycle (e.g., increase, peak, decline, low) did not repeat themselves in sequence. Overall, perhaps cycles did not exist in the strictest definition of the word at Barrow. Perhaps it is time to redefine Barrow lemming “cycles” as annual population fluctuations that exhibit patterns over time.

 Read the full abstract and paper here: https://www.mdpi.com/2076-2615/15/23/3436

Holt, D. W. (2025). A Historical Review of Our Knowledge of Brown Lemming Population Cycles at Barrow, Alaska: Cycles No More or Never Before. Animals, 15(23), 3436. https://doi.org/10.3390/ani15233436

Keywords:

Alaska; Barrow; brown lemming; collared lemming; cycles; density; movements; indicator species; population fluctuations

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