Hunting techniques. Because squirrels use several chambers for sleeping throughout the active season Michener , breached sleeping chambers were not necessarily in use at the time of excavation. For hibernation, each Richardson's ground squirrel inters itself within a closed system that consists of a hibernaculum chamber, a blind-ending tunnel arising from the single opening into that chamber, and a blind-ending drain tunnel Charge ; Michener Seven hibernacula were too damaged to assess the badger's route of entry.
Proportion of excavations by North American badgers terminating in tunnels or chambers of Richardson's ground squirrels. Number of freshly dug excavations for which both size and type of terminus were recorded. Whereas all badgers used excavation as a technique for capturing Richardson's ground squirrels in all years and at all times of year, plugging of ground-squirrel tunnel openings was more temporally limited.
Methods of plugging. Soil was either scraped from around the opening of the tunnel or the badger initiated an excavation at a tunnel entrance then used that excavated soil to plug the opening. Plugging was not an inadvertent consequence of excavation activity. Observation of the mother badger during 2 successful and 6 unsuccessful hunts on 6 days in July revealed that she frequently dashed from an excavation site to a nearby squirrel entrance into the same burrow system, inserted her snout and inhaled deeply several times.
She then positioned herself over the tunnel, with her mass supported on the hind limbs and lower back, and rapidly broke soil and sod from around the opening with alternating right and left fore-arm strokes in a digging action similar to that described by Quaife as soil cutting.
Dragged soil usually originated from a mound created by the badger's activity that night, but sometimes came from old ground-squirrel mounds. Dragging created a conspicuous ribbon of soil that began at the source mound and invariably terminated in a ground-squirrel tunnel entrance. A furrow marking the track of the badger's body was often visible in the ribbon of dragged soil Fig.
Plugging with dragged soil was more common in than or , was infrequent in , and did not occur in other years Table 1. Entrances into burrow systems of Richardson's ground squirrels plugged by an adult female badger in summer The tape measures lying on the ground are shown for scale; tape width is 1.
T indicates the location of the plugged entrance. Relative positions of soil and blocks revealed that the badger dragged soil cm from a fresh excavation out of sight in upper left , then moved the 1st block 1 60 cm, and next moved the 2nd block 2 45 cm. Original locations of the 2 moved blocks, known from marks that had been spray painted on the ground, are indicated with outlines and numerals corresponding to the blocks.
Two other nearby blocks in lower left were undisturbed. When a wood block was used as a plug, the badger usually firmly jammed the object into the ground-squirrel tunnel in a vertical or semi-vertical position, sometimes with the majority of the block below the ground surface Fig. The ground at the site from which blocks originated was never disturbed. Plugging with objects occurred only in 2 years Table 1 , autumn 7 tunnels on 5 nights and summer 16 tunnels on 9 nights. Of 23 tunnels plugged with 37 objects, 12 were plugged with a single wood block, 9 with 2—4 wood blocks, 1 with 1 wood block and 1 clay brick, and 1 with a rock.
Fifteen of those tunnels were plugged only with objects and 5 with an object plus adjacent soil or sod. Three tunnels were plugged with 1—2 wood blocks plus soil dragged , , and cm from a different direction than the blocks, indicating that objects and soil were moved separately Fig. Function of plugging. Between h and h on the night of 22—23 June, the badger excavated 6 tunnel openings and plugged 7 openings 3 with adjacent soil or sod, 2 with dragged soil, and 2 with 2 wood blocks in each in a burrow system occupied by a radiocollared adult female.
The squirrel was killed by the badger, but her sleeping chamber appeared not to have been breached, so the badger presumably captured the squirrel in a tunnel or at the surface. Between h and h on the night of 28—29 June , the mother badger excavated 1 opening and plugged 9 openings 4 with adjacent soil or vegetation and 5 with soil dragged 90— cm into another system in which a radiocollared adult female and 2 radio-collared juvenile daughters were sleeping. The mother squirrel and a daughter with whom she was sharing a sleeping chamber fled from the system and separately sought refuge in nearby burrow systems.
The other daughter, who was sleeping in a chamber 2. Because family members slept in the captured juvenile's sleep site the next night, I deduced that the chamber remained intact and that the badger had captured the juvenile as it fled. The mother badger was not always successful at entrapping squirrels. Although she excavated 3 openings and plugged 10 openings 9 with adjacent soil or sod and 1 with 3 wood blocks moved 75—90 cm into a burrow system on the night of 29—30 June, all 3 radiocollared juvenile females sleeping in this system evaded the badger by fleeing to 2 nearby burrow systems.
Likewise, on the night of 11—12 July, 4 radiocollared ground squirrels sleeping in 2 adjacent burrow systems successfully evaded the badger, either by moving to another part of the same burrow system 2 juvenile females or taking refuge in neighboring burrow systems 1 adult female and 1 juvenile female , even though the badger had dug at 12 sites and plugged 14 openings 7 with adjacent soil or sod, 6 with soil dragged — cm, and 1 with a combination of soil dragged cm and 2 wood blocks moved 75 cm.
The mother badger resident in summer often started hunting before ground squirrels retired for the night, again with variable success. On 14 July , I observed the mother badger spend 70 min using a combination of excavation and plugging with adjacent material to eventually capture a juvenile squirrel underground at h, after which she immediately carried the squirrel 87 m to her den site.
The next evening, she spent 53 min excavating and plugging another burrow system occupied by a juvenile, but at h the squirrel found an escape route while the badger was underground; s later the badger abandoned the excavation.
Plugging of tunnels in autumn also appeared to be attuned to the presence of active squirrels. On 20 November, fresh squirrel tracks in the snow around a tunnel entrance indicated the presence of an active animal and that night the badger plugged this tunnel with snow, the only instance of plugging after mid-October that year. Individual variation in hunting technique. The juvenile badgers were never observed to accompany the mother while she was hunting, so badger excavations were attributable to the activity of a single individual at all seasons and in all years.
Two badgers had distinctive hunting techniques. Only the badger resident in autumn and summer used all 3 methods of plugging squirrel tunnels. Likely this badger, presumed to be the mother badger that hunted in summer , was also present in autumn and sporadically throughout , the only other years that both adjacent soil and dragged soil were used for plugging Table 1.
Even though mounds of soil were available in all 12 years that badgers hunted Richardson's ground squirrels, soil dragging was limited to — A shortage of objects suitable for badgers to move might account for the absence of object use before Thereafter, the number of wood blocks on the site steadily increased until late , yet plugging with objects last occurred on 23 July , the final day that the mother badger and her offspring were resident.
Seasonal variation in hunting activity over a year period revealed that North American badgers frequently hunted hibernating Richardson's ground squirrels in autumn, sometimes hunted infants in spring, and rarely hunted active squirrels in summer. Seasonal changes in abundance of excavations for Columbian ground squirrels S. Collectively, these data indicate a propensity for badgers to hunt ground squirrels in the vulnerable life stages of infancy and hibernation. In contrast, prey remains in feces and digestive tracts Jense and Linder ; Messick and Hornocker ; Snead and Hendrickson indicate that lined ground squirrels S.
Although movement and odor likely enable badgers to detect active ground squirrels more readily than hibernating animals, active squirrels can potentially elude capture, whereas torpid squirrels are unable to flee. Indeed, hunting success on hibernating animals was often so high that badgers temporarily cached surplus carcasses in October and November Michener Badgers that hunted Richardson's ground squirrels in spring focused their effort on capturing infants and they infrequently plugged any of the openings into the sleeping systems that females used for litter rearing Michener Squirrels are able to carry only 1 offspring at a time in the mouth Michener , and the rarity with which mothers rescued 1 or 2 infants suggests that badgers usually located the nest chamber rapidly and consumed the entire litter, with only the mother eluding capture.
Columbian ground squirrels commonly rear infants in a portion of the burrow system accessed via an inconspicuous hole McLean , and badgers almost always plug that opening when hunting preweaned litters Murie Nonetheless, as with Richardson's ground squirrels, mother Columbian ground squirrels frequently survive attacks that result in loss of the litter Murie Both the activity of prey and the identity of the badger influenced the use of plugging by badgers hunting Richardson's ground squirrels.
In early summer, after juvenile squirrels have been weaned and before most adults have entered hibernation, plugging likely abets capture by limiting escape options for active squirrels and, indeed, plugging was used extensively in the only year that badgers resided on the site in June and July.
Knopf and Balph likewise noted that badgers plugged burrow systems occupied by female Uinta ground squirrels with weaned young. Badgers that hunted in September—December, when most or all Richardson's ground squirrels were in hibernation, usually did not plug tunnel openings. However, plugging was common in the 2 autumns preceding the summer residency of the mother badger, particularly in September and October, suggesting that this badger incorporated plugging into the hunting repertoire when juvenile male squirrels were not yet in hibernation.
Although not always specified, previous reports of plugging by badgers imply that the source of material is adjacent soil or sod Knopf and Balph ; Koford ; Lampe ; Murie , and I found that soil and sod from around a tunnel entrance were the most common materials used to plug tunnels of Richardson's ground squirrels. Additionally, 1 badger on my site regularly used 2 other methods of plugging, dragging of soil and insertion of objects, that involved targeted movement of material over short distances 20— cm.
Because the movement of such materials was performed separately from excavations into the same burrow system and the materials were appropriately positioned to occlude openings of tunnels in that burrow system, I inferred that the action was intentional rather than inadvertent.
Beck defined a tool as an object in the environment that is not fixed to the substrate and which is manipulated by the user, and a tool user as an animal that establishes effective orientation of the object to alter some condition and thus attain an incentive. Beck's definitions, which continue to be widely applied Chevalier-Skolnikoff and Liska ; Fragaszy and Adams-Curtis ; van Schaik et al.
Thus, foraging tools are detached objects associated with food gathering by virtue of the user's manipulation of that object relative to the food source Alcock ; Griffin ; Lefebvre et al.
Given that throwing sand at prey qualifies larval ant lions Neuroptera and worm lions Diptera as tool users Alcock ; Beck ; Griffin , aimed displacement of soil from one site to another site to entrap prey qualifies badgers as tool users. A more conservative interpretation might limit tool use just to aimed movement of discrete objects distinct from the substrate. Thus, the badger that hunted Richardson's ground squirrels in autumn and summer qualifies unambiguously as a tool user because it moved objects dissimilar to the soil substrate, primarily wood blocks, and positioned those objects in tunnel openings as an entrapment method when hunting active prey that could potentially elude capture.
For an organism to incorporate tool use into its behavioral repertoire, it must interact with moveable objects and have the means to move such objects Beck I was unable to determine whether the badger that moved objects used its paws or mouth, but precursors to both types of object manipulation form part of normal behavior. Digging involves dexterous motions of digits and wrist that are underlain by skeletal and muscular modifications that permit both strength and manipulation Quaife , and killing and carrying of prey involve a controlled bite that rarely penetrates the skin Michener ; Michener and Iwaniuk One common class of tool use is for extractive foraging of food that is embedded in a matrix or encased in a hard outer covering Beck Among mammals, well-supported examples of tool-assisted foraging include use of stone hammers and anvils by sea otters Enhydra lutris to dislodge prey and to crack shells of bivalve mollusks Calkins ; Hall and Schaller ; Houk and Geibel and use of perforating sticks and fishing probes by chimpanzees Pan troglodytes to obtain subterranean termites of the genus Macrotermes McGrew ; Suzuki et al.
Although use of objects by badgers to limit egress of prey by blocking tunnels is the reverse of the use of perforating sticks by chimpanzees to access prey by creating holes, they are functionally similar in that the outcome is increased likelihood of capture of prey that live underground. The list of vertebrate species reported to use tools to extract embedded or encased food continues to increase Hunt ; Stoinski and Beck , but customary or habitual use sensu Whiten et al. Plugging of burrow entrances by North American badgers is a geographically widespread hunting technique Knopf and Balph ; Koford ; Lampe ; Minta et al.
Although use of discrete objects for tool-assisted foraging coincided with availability of numerous moveable objects on my study site and prey capable of eluding capture, ecological opportunity was not a sufficient condition for object use by all badgers. Badgers are solitary animals with a brief association between mother and offspring that lasts 2.
North American badgers are morphologically specialized to capture subterranean and fossorial mammals by excavation, but they also forage opportunistically on a range of vertebrates and invertebrates Lindzey ; Messick Badgers likewise exhibit behavioral flexibility when hunting, supplementing the standard technique of excavation with plugging of burrow entrances Knopf and Balph ; Koford ; Lampe ; Murie , ambushing Sawyer ; Schwab ; Thompson , and hunting associations with coyotes Minta et al.
My study confirms this behavioral flexibility, demonstrates that some badgers adjust their use of burrow plugging on a seasonal basis, and adds the additional techniques of dragging soil and moving objects to occlude openings into the burrow systems of non-hibernating squirrels.
Sea otters are the only mustelid reported to use tools Beck , but my observations indicate that North American badgers also have the capacity to be tool users. I am particularly indebted to D.
Michener who served as my scribe in the field on numerous finger-numbingly cold days. I thank M. Bader, D. Charge, E. To capture prey, badgers give chase and then will burrow after their prey effectively trapping the animal.
They are even known to block entrances to burrows dug by communial rodents like ground squirrels prior to digging after the prey. Badgers spend much of their time in burrows. Badgers are highly specialized for digging.
When burrowing, they use their large claws to dig into the soil leaving telltale scratch marks along the sides of the burrow. Throughout their territory, badgers will have several burrows and will often switch burrows within two days. Badgers are solitary except when young. Such is the case with coyotes. The fleet-footed canid and the burly badger often work together to increase the odds of snatching a meal. While it seems an unlikely pairing, the association of coyotes and badgers works well for both species.
Known for their aggressive behavior, honey badgers have a reputation of being fearless. They typically keep to themselves as they travel daily to hunt for food. When a male honey badger believes his mate is threatened, he will defend her with force. To let others know that they are not welcome, honey badgers mark their burrows with urine and feces. Honey badgers are built tough and can easily escape a predator or fight back. Their loose skin is thick and rubbery, but should something get through, such as the sting of a bee or the bite of a snake, the honey badger has a resistance that allows them to quickly recover from the venom.
The largest of the badger species, Eurasian badgers are also the friendliest. Social behavior is largely dictated by the availability of food and the density of the badger population. When food is scarce, the badgers become more independent. When resources are plentiful, however, Eurasian badgers are happy to share.
The individuals that occupy areas with a lower population overall tend to live separately, as opposed to those in highly populated areas, where the badgers often share their dens and other resources.
Eurasian badgers also sometimes share their burrows with other species including rabbits, porcupines, red foxes, brown rats, wood mice, stone martens, pine martens, and coypus. Scientists investigating the sharing of dens between these species believe that their ability to coexist demonstrates spatial and conditional niche segregation.
While the most common image of badgers is of rotund animals, the smallest of badgers, the ferret-badger of the subfamily Helictidinae , looks little like its larger cousins.
The largest badger, the Eurasian badger, ranges from 22 to 35 inches long and can weigh as much as 36 pounds, while ferret-badgers are only about 12 to 17 inches long and weigh under 7 pounds.
The Chinese ferret-badger is the smallest, weighing between 2 and 6 pounds. There are five species of ferret-badger, including the Bornean, Chinese, Javan, Burmese, and Vietnam ferret-badgers. While they do live in burrows, they don't always stick to the ground. The Chinese ferret-badger is a strong climber that utilizes its skill to snag fruit from trees.
Some, like the Javan ferret-badger, occupy the holes of other animals instead of digging their own. This displays remarkable confidence for their size, suggesting that the stripes may be a warning. Badgers have poor eyesight, so their stripes are unlikely to be for soliciting grooming or attracting mates, and in Reginald Pocock was one of the first zoologists to speculate that it was warning coloration.
They concluded that the European badger, American striped skunk and other middleweight carnivores evolved dazzling patterns to flag up their main defence anal scent glands in skunks; huge jaws in badgers to predators. Despite female badgers eating less and living off fat reserves, winter is nevertheless when they give birth to their cubs, which are helpless, blind and barely 12cm long, with a 3—4cm tail.
Yet this makes sense in the long run, explains Steve. To get this timing right, female badgers must give birth between January and March, with February usually the peak month in Britain.
Pregnancy lasts six to seven weeks in badgers, so it follows that sows need to fall pregnant in December. But mating normally takes place in spring or summer. The solution is delayed implantation. She can also ovulate a second time and mate again while already carrying blastocysts from an earlier mating, and still start the pregnancy at the same time to produce a single litter of cubs.
This remarkable ability is called superfetation. In northern Russia badgers seldom leave their sett in winter. In southern Spain, however, they remain fully active since their main food — rabbits — is still easy to find.
Badger cubs are born in early February, but life for newborns is dangerous. In the first couple of weeks, up to a third may die underground; most of them will have been killed by sows who have their own cubs. The survivors emerge from the sett when they are nine to ten weeks old. Keep an eye on the entrance because they will probably remain in it, or nearby, as well as staying extremely close to their mother.
She will herd them below ground at the first sign of danger, and even drag a cub to safety by the scruff of its neck. Sometimes the sow will take her young on short trips while she is foraging, but she is very wary of danger. When a female appeared in my garden with three very young cubs, she spent most of her time rounding them up and trying to hide them in the flowerbeds while she ate the peanuts on the lawn.
The sow was particularly nervous when there were foxes around, repeatedly rushing at them with her back arched and fur raised to make herself look larger and more aggressive.
Females with cubs may even corner and kill foxes. A few nights later, the sow had given up trying to marshal her cubs; they chased each other around the lawn, seemingly oblivious to any threat from the foxes. Increase your chance of seeing a badger in the wild with these tops tips from the Jack Reedy at the Badger Trust.
Most rural woodlands will have a badger sett hidden away somewhere, and there are even some small urban badger populations if you know where to look. But if you want the best possible chance of seeing badgers, here are some of the best sites in the UK.
By far the most exciting way to watch badgers is to search for an active sett — look for piles of fresh spoil outside, well-worn paths and a latrine pit full of droppings. The telltale signs of these enchanting mammals are far less attractive than the badgers themselves! Pack a waterproof and extra layers, a hat and gloves in a rucksack — it quickly gets chilly after dark.
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