Seeing’s Believing? Deer Eye Lenses Estimate Age

My loss of high-quality personal sight saddens my imagined relations with the citizen nature-lover, as well as the rural-land-owner concentrating on modern fauna in nature. The wildlife manager, as well as many hunters, may want greater deer harvest for several reasons, and will turn to understanding the population that is desired, probably their number and their dynamics.

“More deer” may sound like an objective heard or sensed from the public. However, the modern manager will be thinking of deer population ages, population structure, and answering: “what system will yield, and continue to yield, legally-harvested deer?” Deer ages are needed for answering this question, and getting them for a large population of healthy, wild deer is the ongoing task of the rural land manager.

Biologists have learned that deer, as many other mammals, have eye lenses that continue to grow in size as they age. Lens weights correlate well with deer age; the lens grows consistently, precious for individual survival. Deer eyes, or a sample, may be removed from dead deer at roadside checking stations (having no effect on “trophies”).

Wildlife biologists can use the association of increasing eye-lens weight to estimate deer age. Properly preserved and processed, deer eye lenses, sampled from all deer taken by hunters from a region, produce the data needed for computer procedures to estimate herd dynamics, the results of combinations of natural forces, poaching, food supplies, hunters, season lengths, changes in hunter groups, and future deer populations.

Beaver eye lenses

Photo of beaver eyes lenses from Dr. Giles’s private collection.

Similar survival growth is found in other animals. I’ve seen large samples of properly-preserved beaver eye lenses, clear messages of major studies of wild beaver population dynamics in a large Idaho watershed. Single, large watershed studies provide essential management data, descriptive of the population status, changes, and therefore the future financial resources of land owners. (As described in Chapter 9 of Rural Future, well-managed wild populations of beavers over time contributes to lasting, profitable wild-fur production and tourists’ viewing, among other enterprises.)

For some organisms, as deer, body size and weight tell stories for superior management; for other organisms, well-studied organs provide status and flow for future populations, and their roles in resource production, tourism, hunting, and commercial trapping, within lasting, dynamic, managed systems, fine-tuned to markets, watershed management, local land and water needs, and mysteriously changing human rural population preferences and curiosities.

Rural Future: An Alternative for Society Before 2050 AD describes one system, Rural System, designed to meet the many interconnected rural problems in America, and ultimately worldwide. Visit the book page to download the full manuscript or individual chapters in .pdf format. Subscribe to the Rural System blog to receive more supplements to Rural Future on a variety of topics relating to the future of superior rural land management.

This is a supplement to Rural Future. Find other supplements in the Rural Futures Supplements category.

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