Social Ecology
Packs and pairs: basic social units
Basic social unit of a population of wolves is the pair. Known variations include:
- a mature male and two mature female;
- a mature male and his successor (1 or 2 years old) from a previous pair and from the new partner;
- a mature female with a new partner and his younger brother.
There is no any reason to believe that other combinations would not be possible. There are two reports of packs formed by males, but is possible to be temporary until they find the pair. In Yellowstone was observed a pack that contained two males and 4 females. These wolves were produced by two cubs in separate burrows.
Mech also saw once an adult male, his cub of 1-2 years old and other three cubs staying together after his mate was killed by other wolves, considering that this shall be an exception; a new mature female joined the pack after 10 weeks.
Natural extension of a breeding pair it is represented generally by his offspring or his family. Descendants stay together with their parents between 10-54months, but except for several special cases (some packs may include offspring of up to 4 years), they leave the natal pack.
Adopted individuals
A poorly understood exception from the basic models are the cases when foreigner wolves join a pack that already contains a breeding pair. They were called "adopted" to distinguish them from the wolves that come into the pack to replace a reproductive partner. Most of the adopted are male and most of adoptions are taking place from February to May.
One of the main mysteries of this behavior is that foreigner wolves are sometimes accepted to join the pack while in many other cases they are hunted, attacked or killed. A suspicion would be that the most of the adopted are between 1-3 years old while a high percentage of killed wolves are adults. The tests in captivity have shown that the degree of aggression depends on the age and residence statute of the wolf involved. From 27 packs studied, nine contain adopted individuals. Adopted wolves may stay in the pack from one day to one year.
Couples formation
The main method is the dispersion of wolves of different sexes in order to encounter each other.
Must be clarified that every wolf is a potential breeder, and once they start to grow up, the tendency is to try to breed. This idea is contrary to that of some wolves quit breeding "for species good."
To breed successfully, individual wolves must find a mate and a territory with sufficient food resources. In a saturated population, all the territories are occupied, so the only methods of breeding would be:
- to wait until the established mating position opens
A) in the native pack
B) in a neighboring pack
In a neighboring pack
To become an extra breeder inside the pack
Usurpation of active male reproductive
To cut off a new territory of the already existing pack
Multiple breeding
- foreign females are rarely adopted in the packs;
- If the dominant female’s daughter breeds, this thing could explain the role of the adoptions and the reason why the most of the adopted are males;
Two reasons seem to suggest multiple breeding: when the food is in abundance (many women need additional food to produce the cub) or in difficult survival conditions (aggression increases when food is scarce):
Territory overlapping "budding" and separation
Another strategy of breeding is that the detached wolf from the old pack, together with his new mate tries to establish the territory along the territorial edges of the homeland pack, forming a adjacent territory or which overlaps the homeland, a process called "budding";
A variation of this strategy is the split of the pack. Dividing in this sense is different of separation packs during the winter;
Separation of large packs during the breeding season or around this period was reported in Denali where a pack of 20 individuals was divided in two: one of 11 individuals, 9 other individuals;
It seems that this division occurs because of related breeder couples, when a male stranger breeds with the daughter of alpha couple. It is supposed that the secondary mate will give birth to some cubs just like the alpha pair, because the dominant couple controls the feeding off the cubs, these two couples may compete for this food and they become aggressive. The solution is to split up the territory and resources, it is necessary only when the food is insufficient, thus explaining why not split up large packs every time in a year;
Individuals which occupies a part of the territory already belonging to another pack, attends areas located along the joint space of the territories; solitary wolves often attend more marginal lands until meet their mate.
The usurpation of a dominant breeder
The last way in which wolves can breed in its own pack is to usurp the position of a dominant wolf;
Without doubt the most dangerous strategy to gain a position that would facilitate breeding right is the challenge of a dominant breeder. Such fights can become deadly in captivity, they did not happen so often in the natural habitat where the weaker partner can escape from this conflict;
The conflicts that lead to the killing of one of the wolves happen in freedom and those who lose are the wolves which are near the edge of a territory or inside the neighboring territory;
A disproportionate number of cases of wolves killed is among adult breeders, but subordinates adults are also killed;
Were cases when an entire pack usurped the territory of another pack, invading and killing several individuals (the number of the wolves belonging to each pack was equal);
Why the wolves are living in packs?
The wolf and the wolf pack in the human mind are associated to the image of a child connected to a family. Human family is a good analogy for the wolf pack. Some cubs can survive without their parents beginning with the age of 4 months. Permanent canine teeth are formed at 7 months old, long bones growth ceases at 12 months old and some females and males are able to breed at 10 months old. Then why the wolves stay together with their parents for more than 10-54 months, when other young mammals species leave early?
Pack as nursery
One possible answer is that there are large variations in the maturation of a wolf. Psychologically, the wolves can not be completely mature only at 5 years. Continued association with the pack of young wolves may simply be a way of maturing of the cubs. From the point of view of the parents, cubs monitoring until their maturity may be the best way to ensure that they grow properly. In addition, long term association with the parents increases the opportunity of the cubs to learn most of the subtleties of hunting and feeding behavior which are not instinctive.
Pack and prey size
There are several evidences such as the pack size may be influenced by other particular factors, pack size varies depending on the size of prey, reaching an optimum number, this could be the one that best allows predation with the lowestenergy consumption and the greatest amount of energy returned. This relationship between the pack and prey it is not completed. Small packs tend to feed on garbage (scrap) and small animals like deer, and the big packs with elk and bison (in Romania with stag).
Factors that complicate
Biologists have advanced the idea that the packs exist because they can promote greater efficiency in hunting and it seems a logical conclusion. But several factors complicate the things.
If a large number of wolves was necessary to catch large ungulates, it would be difficult for a single wolf or a pair to survive and produce cubs that increase the pack. In fact it is not necessary a large number of wolves to kill large prey. It were recorded solitary wolves that killed a prey, registered as the higher for the wolf species, including adult elk and bison.
Even when a pack attack the prey, each member not participate significantly in the attack.
Due to the experience and power that has the breeding pair, it will tend to take the lead in tracking and attacking the prey, in this case is not clear how the younger members of the pack get involved in hunting.
Another factor is that the size of the pack in the usual sense, is not necessarily to be the same as hunting group size. In winter, when wolves are focused mainly on hunting not even then does not hunting all the pack. A pack of 15 wolves broke in two during the winter of 1961 and again in 1963 and 1965.
Pack size and hunting efficiency
It seems obvious that group hunting will increase hunting efficiency. A good test to check this theory is to determine the amount of food acquired per wolf for packs of different sizes. However, a possible price paid for this advantage is the fact that multiple hunters must share with each other the gain. Many other theoretical and empirical considerations have led to the conclusion that "group hunting is often a consequence of the herd instinct, than of evolutionary reasons”.
A good test of the hypothesis that large groups of wolves are more efficient in hunting and killing the prey is the determination of the amount off ood per wolf on different packs sizes. A wolf pack from Isle Royale counting 15 hunted elk for two years after that has divided in two, but after this amount of food obtained which was higher than that obtained during the two years. Similarly, solitary wolves from Minnesota killed more prey per wolf than a pack of 5wolves and the pairs killed more prey per wolf than packs. To a more detailed test these conclusions remain unchanged: the more the pack is higher, the lower amount of food returns to each wolf.
Excess food consumption
Packs that hunt large preys have the regular amount of food surplus that remains behind them and allow the spread of some species that compete with them in eating small animals. From the viewpoint of the cubs if food is provided, it is advantageous for them to stay with their parents than to try to find resources on their own.
The wolves who hunt deer can’t support a lot of cubs, while those who are hunting bison and elk have this possibility.
Were found cases when wolves from a small pack were hunting small animals to be able to stay in the group. If they can hunt enough small prey, then there is a chance that more individuals can accompany the pack only in normal cases. This behavior confirms the theory that when stress factors in terms of food availability diminishes, hunting group size may increase.
Regulations of pack size
Because the cubs were fed by their parents since they were little, the tendency of the cubs will be to remain with their parents until something will obliged to leave the the pack. However, because each year there are new offspring, old cubs must compete with the little ones for food. Priority is for the little ones, they eat first, if it is enough food, the big ones are allowed to access to food.
Some wolves leave the pack at 5 months, others remain more than 3 years, so competition for food may be one of the main reasons for leaving the pack and it can be feedback mechanisms that regulate the pack size through dispersion (leaving the pack).
Another factor would be the dominance of pack hierarchy. When competition for food increases, the first to leave will be members of the lower classes.
The best evidence that the competition for food affects the dispersion comes from southwest Quebec.
There young and adults in a low density area with elk, have made several 5 km trips and more from their territory than did wolves from neighboring territories with high density of food, more than, females do such trips to a higher percentage than males. They takes between several days to several months, with an average of more than 22km away in a straight line and eventually culminated into dispersion.
Territoriality
Territory’s size
There is a general relation between the size of a specimen of wolf and its area size. In general, the bigger the animal is, the more it increases the demand for food, and space necessary to obtain food.
Pack territory size depends on a variety of factors and it can vary from 18 square km / the pack to 1300 square km / the pack. The wolves live in small territories, well defined when they have an abundant prey, they stay for many years in the same place. Small territories are characteristic of areas in which prey does not migrate and small territories are characteristic of areas in which prey and does not migrate, very higher territories - areas where the prey migrate (in Alaska, where prey is caribou, the wolves migrate hundreds of kilometers each year). Other factors that affect the size of the territory which is defended by the pack, it is the climate, the presence of other packs and terrain’s nature. In areas with high density of population, wolves have small territories.
The wolves have a tendency to have higher territories in areas where there are other large carnivores: lynx, bears.
Territorial behavior
The territory of an animal is simply defined as the area in which it can defend itself by other animals of his species. This is the difference between the territory and spreading area, in the last one the animals lives but interferes with other individuals of the same species, which are not able to defend themselves. It is very difficult to determine how territorial wolves are, this thing involves the monitoring the moves of the entire wolves pack for a long time, and determine how interact with other wolves from its territory. Experts have observed packs of wolves that attack other wolves (Mech, 1970) and large packs that attack smaller packs. The wolves rarely are friendly with other unrelated wolves with the pack, the last ones have a well-defined territory that may stay. Pack territory will include areas for hunting and travel, so they are very large, but packs are separated by great distances, as such overlapping territories isinsignificant. When overlapping territories, packs will do so to stay away from each other.
In setting a territory, one pair of wolves must select one area much larger than necessary because it is expected that they would produce an average of a total of five or six cubs which must be fed. When cubs are six months they eat as much food as an adult, which means that the pack the size triples, as well as the necessary resources for survival.
Moreover, some packs include not only one pair of wolves with cubs but also the offspring from previous years, pack size being able to rise to over 15 individuals. Pairs of wolves that colonize habitats already occupied and which are trying to cut apart of the territory of the existing mosaic will have to start with small areas and then to try to extend. n many populations of wolves persecuted by humans, this exploitation leaves free space in this large mosaic. So the pairs can acquire the entire territories whose occupants have been recently exterminated.
Wolves frequently changes its territory in search of the prey or increase or diminish it as a response to prey movements. Packs were seen traveling long distances in winter, is not uncommon for a pack to move to 50 km per day.
Solitary wolves do not have a defined territory and travel long impressive distances to find mate and to breed. (Van Tighem, 1999). For example, a she wolf named Opal had been a radio transmitter fitted in Kananaskis (in Alberta) and was found later in Idaho, north of Yellowstone. It has then traveled over 1000 km. Another she wolf named "Pluie", which was caught and he was fitted with a radio collar in Alberta Central, traveled in an area of 100 000 sq. km. After being fitted with a radio collar, it went to Banff, joined the pack from there, left the pack and went to the flat Valley of British Columbia, he went to Idaho, then returned to Banff. This journey it took three years. Later the collar was found several hundred kilometers south in the north of Waterton-Glacier International Peace Park. The researchers have lost its track, after which they found it near Invermere, British Columbia. Unfortunately he was shot by a hunter.
The marking of the territory
The wolves use several methods to mark their territory. In the well defined territories the most important method is the marking with scent. The wolves urinate to mark their territory so that others can detect the presence of the pack. The wolves have a very good sense of smell, so that an intruder is discovered quickly. The wolves rarely tolerate other wolves in the territory, RD Lawrence, in his book the Trail of the Wolf, is describing some scenes in which there were no altercations when the two packs have met.
When a wolf marks his territory and will raise one of the hind legs and will splashedwith a small amount of urine the marked place (a tree, a bush, a rock). This type of urination, called raised leg urination (Raised leg urination - RLU) is different from ordinary urination, when the wolf splashes urine on the ground. RLU is done by alpha wolves (males and females), with a greater tendency by alpha males. Alpha females mark their territory, especially during the breeding, the female urinate directly on the ground first. All other females from the pack, like inferior wolves or juvenile will urinate bending the hind legs. Candace Savage in his book The Nature of Wolves says that sometimes all the wolves from the pack will mark a place, wolves waiting their turn in line to mark. Solitary wolves will not mark their territory by RLU because the pack does not discover its presence
Alpha wolves will mark the limits of the territory with urine within every 350 m. The limits will be marked several times, these limits are important to not cause altercations between packs. Wolves will not mark where there are already marks left by other wolves, foxes, deer etc.
Wolves will rub his neck on the tree trunk, will lick it or will scratch the ground (often after urinating). So to the urine smell will be added the smell left by the glands situated on the neck or between the fingers.
Communication
The howling and the marking territory by urinating and scratches are the most common communication methods used by wolves. The howling is one of the most important means of communication among wolves. There are many preconceptions about wolves howling. Contrary to popular belief, wolves do not howl only in full moon days and not only when they are staying. Also wolves howl not only at night, they can howl during the day, evening or morning. Wolves often howl together, the howl was started by a member of the pack, which was quickly followed by other wolves. Under ideal conditions you can hear a pack of about 16 km. During howling the wolf tone of voice changes its a few times, so many people may believe that they are dealing with more wolves than they are.
The howling happens for several reasons. Often the wolf howl before leaving to hunting, possibly in order to gather the pack or after a successful hunt. They do not howl while hunting, in order to not alert the prey on the presence of the pack. A wolf can howl alone, when it is hard for it to find the pack. Wolves may howl after the death of the cubs or parents. The howling is a way of communication between packs. Mech (1970) show that wolves often kept 20-30 minutes of silence after a period of screaming. He believes that this breathe the pack to listen if another pack will give an answer. Wolves howl less between May and July because they are busy with the growth of the cubs born in that year. It is possible that in this time to be kept the silence in order to not attract predators such as shepherd dogs or bears.
Besides howling, wolves can cause sounds such as whining, growling, barking and yapping (Mech, 1970). Whimpering serves as sound of submissive or friendship, so that when dogs or wolves will look like are subjected they start to whimper. Wolves growl when they just put another wolf on the run or when they become aggressive. Wolves rarely bark, and when they do this, it represents either an alarm or play tone.
Social order and visual communication
Wolves usually live in family groups called packs. Most of the packs have in the composition the leading couple (alpha male and alpha females) and their cubs (up to 3 years). Sometimes it may also occur other wolves, relatives of the alpha. In exceptional cases it appears in the pack wolves which are not relatives of the leading couple. In each pack there is an order respected, the body language expressing the position of the wolf inside the pack. It is said that there are four classes of wolves in a pack:
(1) alpha pair: The most often identified as the breeding pair, the pair consists of an alpha females and a male. These wolves will breed and they will produce successors. These wolves are pack leaders, directing them often, but not always, the activity of the pack.
(2) mature animals subordinated (beta): This includes wolves from the pack which are subordinates of the alpha pair. Often there are two categories of dominance in the pack: one of the female and one of the males, but Mech (1999) believes that this thing does not happen to packs which are living in the wild. The highest position that a subordinated animal can reach it is the beta wolf status.
(3) Omega wolves: Most of the packs have one or several omega wolves, which are ignored by the pack. These wolves are trying to become members of the pack but they are rejected by the pack. .
(4) Juveniles: Young wolves who can not have yet care for themselves, had their own position inside the the pack. They will learn through playful fights to survive, these causing a hierarchical order among juveniles, orders that change frequently.
It is supposed that some wolves are born as alpha and others as subordinates. These statements were rejected recently by Mech which followed since 1988 to 1998packs from Ellesmere, Northwest Territories, Canada. Each wolf has a chance to become the alpha and those who do not become alpha will leave the pack to start a new one. The dominance inside the pack could be changed when an alpha wolf dies or another wolf is attached to the pack. These changes occur especially during the breeding season when wolves become more aggressive with each other. The ritual battles go on to become common, although it's rare for wolves to hurt each other.
Alpha wolf is not the pack leader, although in the most of the cases it leads directly the activity of the pack. Although the alpha male is usually the strongest wolf of the pack, alpha females influence the most the life of the pack. It selects the nesting place and therefore the central place of activity of the cubs during the growth. Alpha wolf may lead other wolves during hunting, may choose place to sleep or lead the pack defense against bear attacks for example. Any motivated wolf can do this and may be followed by some members of the the pack. Mech (1970) stated that this it may be an element of democracy in a pack.
The wolves use a large variety of facial gestures or body language to show its specific place in the pack. Wolf tail position may be used to tell if a wolf is dominantor dominated. During social interactions alpha wolves hold their tails very raised and dominated wolves keep their tails down. The wolves which are on very low positions in the pack keep their tail curved on the body or between its legs when an alpha wolf coming at it.
Lupii au si alte moduri de a-si arata pozitia in ierarhie. Un lup inferior se va culca la pamant la apropierea unui lup dominant, blana fiind aplatizata. De asemenea lupul dominat va linge botul masculului alfa. Daca un lup inferior va opune rezistenta unui alfa lup atunci acesta din urma va incerca sa se impuna. Cand lupul dominat cedeaza se va culca la pamant expunindu-si abdomenul si va urina. Acest act se numeste supunere pasiva si alfa lupul va accepta actul ca un fel de scuza.
The wolves have other ways to show their position in the hierarchy. One inferior wolf shall lie down when is coming a dominant wolf, fur being flattened. Also the dominated wolf will lick nose alpha male. If an inferior wolf will resist in front of the alpha wolf then the last one will try to impose itself. When dominated wolf gives up, it will lie down showing his abdomen and will urinate. This act is called passive obedience and the alpha wolf will accept the act as an excuse. The wolves from the pack can become aggressive towards omega wolves if they get too close to the the pack. Small conflicts can occur when the wolves feed on an animal carcass. One dominant wolf may take food from an inferior wolf. (Mech, 1999 and 1970). Into the wild the battles for dominance are less common than in captivity (Mech, 1999). During of 13 seasons spent inside the arctic wolf packs Mech (1999) did not notice any serious challenge to the dominance of the alpha pair. Wolves which can contest the hierarchy leave the pack before reaching the sexual maturity, at 2 years, so the the pack will be stable and will not occur fights for breeding. Alpha female is subjected to alpha male, the contestation of the hierarchy is appearing only when alpha wolf came to close of den in which are the cubs (Mech, 1999).
Wolf’s diet
The wolves are carnivores, with a tendency to diversify the type of food. When they hunt in the pack they kill roe deer, deer, chamois or sheep, cows, horses and dogs. During the spring the tendency is to capture juvenile ungulates. In Romania, the most important food source is the the stag. The wolves can hunt also small animals like rabbits, otters, squirrels, mice, birds, etc. Where there are many wolves, fox becomes a rarity. The wolves also eat carcasses of dead animals that have not hunted. And also consume insects, earthworms, garbage and especially when they are hungry blueberry, blackberry, mountain ash, corn and other vegetables. The wolves also eat grass as a purgative.
The birth and the growth of the cubs
Wolves pairs are formed between December and February. Usually many wolves are pursuing horny she wolves. The she wolf is able to breed only once a year during the heat time (oestrus), which takes only a few weeks. The breeding season last from February to March. Some wolves can breed in January. The breeding season is the period immediately after the winter, in this way the cubs will be able to grow till the next winter. Females become sexually active at 2 years old, but many of them may have puppies up to 4 or 5 years old.
Alpha female is usually the mother of the cubs from the pack . In almost all the cases the father is the alpha male, but sometimes it can be the beta male if the alpha male does not show interest to breed with the alpha female or another females from the pack. If they breed then it can use the force in order to remove the pretenders. Inferior females can breed when the hierarchy in the pack was disturbed.
During the courtship, alpha male and alpha female are very close. They sit side by side almost all the time, even when sleeping. Alpha male and alpha female have a strong relationship all year but go on to become even stronger when ready to breed. Once established, the reproductive pair often remains stable the entire life, few partner changes appear.
Selecting the den
A few weeks before the birth of pups, the female will look for a den, usually in an area with flat slopes and near a water source. The deen is usually a tunnel enough large to be possible for an adult wolf to enter, the tunnel leads to a larger room where babies will be born. It can be used other types of dens: caves, hollows, fox dens, a basin on the ground. The wolves use the den several times but it will be changed if it becomes infested by parasites or disturbed by other animals.
However, the den preparation can start long before the appearance of the cubs can be dug even starting from the autumn. Adults of both sexes together with the cubs from the previous year, participate in the the digging of the den and and the pregnant female food supply.
Wolf dens are usually located away from the the peripheral areas of their territory where there are possible clashes with neighboring packs. Dens situated on the homogenous territory tend to be centrally located, except if there are certain features that may influence selection criteria dens such as water sources. Distances between active dens of the packs placed one near to each other varies depending on the amount of territory.
Alpha male actively protect the den and it will make the predators to go away, but if a human being will come it leaves it. When the female prepare the den, the alpha male or another wolf starts to bring meat close to the den.
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