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Principles of habitat Management Chapter 3 EVERY WINTER, thousands of northerners migrate to Texas. Convoys of motor homes, travel trailers, and camper trucks move south like Canada geese (Branta canadensis). These migratory humans travel hundreds of miles to escape blizzards and ice storms for the sunny days and fuzzy warmth of southern Texas. Northern journeyers pass through several plant communities en route to the Rio Grande Plains. Depending on route, they might see maple-beech (Acer-Fagus ) forest, oak-hickory (Quercus-Carya) forest, longleaf pine–wire grass (Pinus palustris–Aristida stricta) savannas, tallgrass prairie, mesquite–silver bluestem (Bothriochloa laguroides) prairie, juniper (Juniperus)-oak woodland, and eventually , South Texas brushland. Bobwhites occur in all these plant communities. This is an impressive feat. Plant composition, rainfall, temperature, and soils vary considerably from the Great Lakes to the Rio Grande Plains. What is even more impressive is that, excepting a slight drop in body mass going southward, bobwhites remain moreor -less unchanged across their range. A “constant” bobwhite and its ability to thrive in various habitats provide a basis for the principles of bobwhite management discussed in this chapter. We begin with the fundamentals of populations and then move on to the theory of habitat management. “Looking for a spot to die” Bobwhites live in a violent world. Cooper’s hawks (Accipiter cooperii) spy on them from brush thickets. Egg bandits—coyotes (Canis latrans), raccoons (Procyon lotor), skunks (Mephitis mephitis), and opossums (Didelphis virginiana)— maraud day and night in search of nests. And, every fall and winter, bobwhites engage in a deadly battle of wits with hunters and bird dogs in the hinterlands of Texas and other states. Death certainly is easy for bobwhites. Only about 5 of every 100 eggs laid will produce an adult quail. If 100 bobwhites are alive on an Iowa farm on October 1, only about 20 will be alive the next October. Bobwhites in southern latitudes 34 chapter three enjoy a slightly higher annual survival but not by much. Thirty percent survive during any given October−October period in warmer latitudes. What if bobwhites were able to live in the perfect environment, one free from predators, disease, starvation, blizzards, drought, and other catastrophes? Would survival be any better? Yes, but not much better. Bobwhites are not wired evolutionarily for a long life. Even in a perfect environment, one in which the only cause of death is old age, annual survival still will be only about 56%. Generally speaking, then, bobwhite survival is naturally low. As a rancher once commented , “It seems to me that bobwhites are just walking around in life looking for their spot to die.” The low survival is part of the reason that you cannot stockpile bobwhites in the long term. If somehow you were able to eliminate their many sources of mortality , bobwhite populations would not build up over time. This is not to say that you can never stockpile populations. It may be possible in the short term. For example, reducing or eliminating harvest during severe drought, when populations are low, may help maximize the number of breeders entering next spring. Year in and year out, however, low survival is one mechanism that prevents bobwhite populations from growing exponentially. It can be puzzling how bobwhites are able to persist considering such low survival. One explanation is that when dealing in averages (for example, 80% annual mortality), we need to keep in mind that some birds are above average. These birds carry populations on their sloped shoulders. Also, just as nature shortchanged bobwhites in survival, it supercharged them in productivity. The production engine of bobwhites is such that populations are capable of doubling from one year to the next given favorable conditions. Such growth potential is possible because bobwhites lay relatively large clutches and may renest several times in a laying season. Multiple brooding has been documented throughout the geographic range of bobwhites. In the Rio Grande Plains, the largest clutch we have found is 23 eggs. We also have documented some hens renesting up to 4 times. Although these are not the norm, this great reproductive potential helps offset the high mortality sustained by bobwhites. An important principle that emerges from the hard-and-fast lives of bobwhites is that there is little to be gained by tinkering with their survival. Nature has capped the upper limit. Managers can best help bobwhites by providing suitable habitat and plenty of it. the Colin space race The year 1997 is one that will go...

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