Author: Kevin A. Gardner
Animal migration and distribution have always been fascinating and never fully explained phenomenon’s. From the scientist down to the casual observer, the question has always remained as to why some animals truly migrate, while others may be or become intent to live out their lives in a particular area, and in some cases, take on the appearance of migration.
To help better understand animal movement activity, it may be best to start by gaining an understanding of movement as it is actually categorized. True migration can be either long-range movement or very short distanced depending on factors such as the species of animal and the animal’s physical or geographic constraints. We tend to label some activity as migration, when indeed there may be a better or more appropriate category to place this activity in, which is called “redistribution.” This redistribution process may be defined as a spreading-out, to better help visualize it as a type of movement. Therefore, in an effort to cover just the basics, we will limit ourselves in focus to true migration and local redistribution as our two primary categories.
The loose use of the term migration has placed a mental image in the mind of many hunters who have found themselves in a situation where movement activity has occurred and identified incorrectly. “Suddenly all of the deer have left the area and moved out of state.” If you haven’t said it yourself, you have probably heard it. If it were indeed a fact, there would, categorically, be a true migration in effect in that area. Migration is a substantial movement by as little as one individual to the extent of all members of the species within a designated area. When animals move into an area for an undetermined amount of time it is referred to as immigration. To the back end, when animals leave an area for an undetermined amount of time, it is referred to as an emigration. So if my deer herd were to leave the area for the unforeseeable future and reestablished a new “core” area, they have emigrated. When new animals arrive in my area and create a core area, I am safe to assume that these animals have immigrated to my area. That time they spent in transit or trans-locating was their migration. All of the range that they inhabited in-between is held as Transition Range, or land occupied between movement events with no intent to reside.
Let’s first be scientific and explore our widest accepted migration theory. Migration is necessitated by a need for food and/or water sources, to be able to escape seemingly uninhabitable or hostile conditions or, to partake in ritualistic activities. An accepted theory of significance is that certain animal’s breed and birth in specific locations annually and will innately return to those areas for the same activity year after year, requiring migration. This better understanding can help us to rationalize an area being void of animals at a certain time and the true predictability of those animals return. Using that information and education as a strategy for locating animals that truly migrate is the key to successfully finding them at any given point of their movement.
It is then safe to say that by being able to identify the type of range or land that you are seeking animals on is the key to finding them. If you are searching an area where breeding and birthing activity occur, for example, during a time when migrating animals are transitioning to or from that area, you could reasonably predict there to be a lack of animals in the vicinity at that time. This is why having a true understanding of your herd as migrating or redistributing is so important.
Redistribution begins to occur when any type of event has changed the actual number of a particular non-migratory animal your area. That event could have been as subtle as one of those animals having been hit by a vehicle, a poaching, a fatal injury, or a true partial emigration of some of that same species. The remaining animals will now redistribute themselves according to this change or event. This is the hardest and probably the most important type of activity to understand as it directly affects how quickly resident herds of animals (or non-migrating animals) can disperse or seemingly disappear.
In pulling this information together and beginning to look at how it impacts our herds, the object of anyone trying to locate these animals would be to properly identify migration or redistribution activity, and rethink observations and strategies based on a better understanding of prevailing movement patterns. When deer for example, seem to have simply disappeared from a particular area that they normally thrive in, or a buck is harvested that has never been documented in the area during thorough pre-scouting, it is a good indication of redistribution activity. Only by understanding the process can you begin to utilize the information strategically on the hunt or to secure better levels of natural inhabitancy by your target animals. That is to imply that if you want to sustain the animals from this redistribution, that you work with the habitat to have better than adequate food, cover, and water, to support them.
The terms Core Area and Home Range are names given to an animal’s life long geographical boundary. The acreage within these boundaries is constantly being impacted by factors such as competing members of the same species and human encroachments. What that means is that an animal will establish itself in an area and will confine or be confined to a particular radius or distance that surrounds it. Those far end barriers may be established food and water sources or even actual geographical obstacles like a river or mountain. With regard to the actual geographical boundaries, there may never be a change within that specified area when there is an entirely different story of redistribution and other activities affecting population dispersion. Just because a physical barrier is the farthest distance an animal could move within the core area does not meant that it will ever venture into that far reaching area based on the redistribution of other animals.
Dominance in the animal kingdom is a matter of fact that changes the dynamics of dispersion or distribution very fluidly. The incidental removal (as referred to above) or harvesting of a dominant buck from an area, for example, will change the dynamics of immediate dispersal of his herd or harem. Rival animals can now encroach upon his core activity area. A new pattern of events will begin to unfold that were previously inhibited by the dominant animal’s presence in the area. Smaller, less dominant bucks can now spread out and will begin to be seen in other areas, never before available to them without a fight. Another possibility exists in that by removing an animal that may have been in antler de-generation due to age, and still been a dominant presence in an area, could allow new genetics or even weaker genetics to be distributed. This redistribution could be creating an even better bloodline interaction or worsening the trophy value, depending on the situation, with the barrier of the older buck removed.
To look at this from another angle let’s change our example-harvested animal to a dominant or lead doe. In any herd, the lead animal is the deciding animal in several factors that concern movement. This lead animal will determine when, by what route, and at what pace, the movement will take place. For the majority of the year the females of the herd make the movement decisions and the males simply try to keep the group together as much as possible. This is especially true during the rutting process. Male animals being a lead is more common when speaking in terms of bachelor-banding activity that males utilize during non-competitive times. Often from late winter to early fall the males will group into these bachelor bands and stay very close together night and day. During that time, a dominant male would tend to lead the movement of that band.
When the lead animal is removed from the herd, the pecking order will establish a new leader. This new lead animal may follow the same exact movement patterns that were established by the previous dominant animal or go their own path in deciding movement. You can quickly see how the entire dynamics of an area changes with almost every animal that is removed. Understanding this impending activity and reacting to it when you can determine that specific animals have been harvested or removed will be the key to calculating a change in distribution and may require a complete strategy change for hunting activity.
This may be a lot to consider and likely impacts hunters who rely on natural movement of animals such as archery or any early season hunts where animals are anticipated to move on a schedule at a more visible pace. However, even the rifle hunter who is working alone or in a small group during the latter part of their season, where little or no pressure is being felt, this herd knowledge becomes more important.
In Summation, if you can learn to identify your herd hierarchy, can fathom core areas, have done your scouting and research, you will be able to react to these changing conditions or at minimum realize the need to react when migration activity occurs or a key animal is removed.