Biological Objectives

Cerulean Warbler. Photo: Bill Hubick

It has been said that wildlife conservation was largely opportunistic for many years, but in truth has always been undertaken on the basis of implicit biological objectives, often in the form of more deer or more turkeys or the like. Habitat was protected or improved with the hope that populations of target species would respond in a positive manner. In many ways, this practice has not changed over time.

A number of years ago, the approach became somewhat more rigorous in that conservation actions were taken to satisfy habitat objectives for a particular region. A hypothetical example could be a state that had an objective of establishment of two wildlife management areas in each county. Again, it was implicit that such action would provide hunters with game animals to pursue. Habitat objectives were set with the assumption that achieving them would achieve population objectives.

All of this became more complex when conservation of rare or endangered non-game species became a higher priority, a gradually increasing objective that came into prominence in the 1960's. In these cases, habitat was protected or managed to prevent the extinction or increase the population size of one or a few species. This was no longer primarily a habitat objective, but rather a population objective that was to be achieved through habitat conservation.

With the advent of Partners in Flight came the notion of simultaneous objectives for a large number of non-hunted bird species. Often, objectives were set for those species within a habitat type that had the most demanding habitat needs, with the assumption that if these needs were met, the needs of other species in that habitat suite would be met as well. These targeted birds have been variously called "umbrella" or "focal" species. This is more complicated, but is not fundamentally different from the game species example noted above, in that habitat objectives are set with the assumption that, if met, populations will respond in a desired manner.

In recent years, however, the notion has arisen that habitat objectives are insufficient organizing principles for conservation. After all, this is a business of bird conservation, not bird habitat conservation. In this school of thought, conservation of habitat should be undertaken in order to achieve explicitly stated population objectives. This has become a popular concept, and, indeed, the government of the United States has been taking an ever-stronger position that its agencies should undertake their conservation efforts in order to achieve population objectives, and that response of target populations should be the ultimate measure of success.

Measuring success on the basis of population response makes sense, but it is somewhat problematical, particularly with migratory birds for which we have only a vague notion of what is limiting their populations. The US Fish and Wildlife Service may do a wonderful job of creating Cerulean Warbler breeding habitat, for example, but populations of the bird may not respond positively if they are limited by conditions of their wintering grounds. Furthermore, even though achieving positive population response is an important objective, measuring that response with confidence is usually a remarkably difficult thing to do.

So, bird initiatives, Joint Ventures, state and federal agencies, and others are basing their conservation planning more and more on population objectives. There are, thus far, perceptions that there are political payoffs to such an approach. The jury is still out as to whether this approach is ultimately sensible.

There are six questions (at least) that should be asked regarding the setting of population objectives:

1. Is there a biological justification for the way that objectives were established? (usually there is not).
2. What is the social justification for the way that objectives were established? How is this assessed?
3. Are there biological benefits derived from the establishment of objectives? (beyond linkage to conservation design and evaluation). This is perhaps the most difficult of these questions to address.
4. Are there political and/or financial benefits derived from establishment of objectives? Because many people assume that the answer to this question will eventually be "yes", this probably drives objective setting more than any other factor.
5. Has the capacity of habitat within a region or a range to support a particular objective been assessed? Is the objective too high to be realistic, or too low considering potential opportunities?
6. Are objectives for one priority species in conflict with those for another species? Would optimization for an avifauna result in changes in objectives?

The nature of objectives can vary, based in part on available information:

• Existing population estimates can lead to objectives framed in terms of absolute numbers. (The concepts surrounding population estimates are quite complex, but such estimates do exist for many birds). This is what Endangered Species Act Recovery Plans do, and that's a problem because the original estimates are almost always very low in rigor.
• Knowledge of population trends can lead to objectives based on change in those trends, or a multiplier of current status (double declining populations, for example). This is what Partners in Flight has done.
• Knowledge of vital rates can lead to reproductive success objectives. This is what in at least some cases in the waterfowl conservation community.
• Knowledge that a species is very rare can lead to an objective of preventing extinction. This is what Alliance for Zero Extinction does. It's a necessary starting point

Finally, there is a clear drawback to having population objectives - What happens when they are exceeded? Does the political will and financial support to continue conservation efforts dry up? Is continued conservation effort in that habitat still warranted?