Characteristics of hares and new technologies for control
Lai Shuli [Yoshiyama Huayao self-media network debut]
In recent years, with the improvement of national ecological awareness and the successive implementation of the national "six major forestry key projects", the forestry industry has ushered in a new era of rapid development, which is highlighted by a significant increase in the area of young forests, the rapid natural recovery of barren mountain vegetation, the effective reversal of the momentum of ecological environment deterioration, and the sharp increase in the population of wild animals such as hares, pheasants and weasels. Since the former State Forestry Administration officially listed hares in the "List of Beneficial or Important Economic and Scientific Research Value of National Protection" in 2000, it has provided legal protection for the growth and expansion of the hare population, and the hares that can be hunted in the past have been upgraded to "three haves" wild animals, resulting in a significant weakening of the anthropogenic inhibition effect of the hare population. However, with social progress and the growth of the hare population, the area of hare damage is also increasing, especially in nurseries and newly planted young forests from one to five years old, and some areas even reach the outbreak of fields. The 2015 statistics of the former State Forestry Administration show that the average annual occurrence area of rabbit (rat) infestation in China is 9.3 million hm 2, and the population density of hares per unit area in some areas is as high as 242 /km 2, and the affected afforestation tree species are almost all-encompassing, the average victim mortality rate is about 50%, and some are even 100% mortal, resulting in direct economic losses of more than 80 billion yuan. In China, rabbit gnawing occurs in almost all provinces and regions except East China and South China, especially in the "Three Norths" region, which is the most seriously affected, and the threat to the security of forest resources cannot be underestimated. China is also the country in the world that suffers the most from hares and has the widest range (area) of occurrence [1]. Therefore, it is necessary to develop a feasible response to rabbit infestation.
1 Taxonomic distribution and bioecological characteristics of hares
1.1 Classification and distribution
Hare is a general term for species of the family Leporidae , belonging to the animal kingdom , the chordate phylum vertebrate subphylum mammalian subphylum Euphropodidae rabbit-shaped ( rodent ) order. There are 40 species of hares in 9 genera in the world, distributed in Europe, Asia, Africa and the Americas, of which the most widely distributed and most species are lepus, about 22 species, and 9 species in China. Among them, the snow rabbit (Lepus timidus), the northeast rabbit (Lepus mandshurid-us), the northeast black rabbit (Lepus melinus), the South China rabbit (Lepus sinensis), the grass rabbit (Lepus capensis) and the plateau rabbit (Lepus oiostolus) belong to the Palearctic boundary, the Hainan rabbit (Lepus hainanus), the Yunnan rabbit (Lepus comus) and the Tarim rabbit () Lepus yarkandensis) belongs to the eastern boundary, Hainan rabbit, Tarim rabbit and northeast black rabbit are endemic species in China, and the medicinal value is relatively large, such as northeast rabbit, grass rabbit, plateau rabbit and snow rabbit.
Grass rabbits are also known as desert hares, cape hares, Brown hares, Arabian hares, and some places also call them Mongolian rabbits, jumping cats, mountain jumpers, European rabbits and so on. It is widely distributed in Liaoning, Kyrgyzstan, Hei, Mongolia, Jin, Shaanxi, Ning, Qingdao, Gansu, Xin, Hebei, Lu, Henan, Anhui, Suzhou, Hubei and other northern Yangtze River areas, and is also distributed in Qianhe northern Yunnan and eastern Sichuan. It is this kind of grass rabbit (referred to as the hare, the same below) distributed in the northwest region of Liaoning.
1.2 Habitat
Hares mainly inhabit low-lying areas, woods, meadows, fields, shrubs and forest edges on both sides of ditches near farmland, and the main activity time is at night, and the visual and auditory senses are more developed. It feeds mainly on trees (bark, young branches, saplings), weeds, crops and wild vegetables, and is more harmful to large seedlings in nurseries, young trees in afforestation fields and crops. Studies have shown that where the following 3 conditions are met, the number of hares is high, and vice versa. The first is to have an environment where you can hide, such as young trees, shrublands, and wastelands with short trees. Second, it is possible to look at predators without affecting the area of escape. The third is the area where there is a water source and food nearby. Compared with water, hare food is more readily available, especially in dry seasons such as late autumn and early spring, where the importance of water is more prominent. In addition, female rabbits who are breastfeeding also need to drink enough water every day. Thus, the area of severe water scarcity of hares
Populations are generally relatively small.
1.3 Life habits of hares
Hares have never had an absolutely fixed habitat. Except for the simple and fixed nest during the nursery period, the rest of the time is a wandering life, but the range of its wandering activity is relatively fixed, and it does not easily escape the area where it lives (about 3 km radius). In spring and summer, it often lives in shrubs (grass) and dense young forests; in autumn and winter, when the grass and trees wither, the hare's hiding place may usually be a lump of soil, a bush of shrubs, or other suitable places. The hare will use its front paws to dig a shallow small hole to hide itself, this kind of hidden hole is commonly known as "cube", the length and width are about 30 and 20 cm, the front end is flat and shallow, the back is gradually deeper, and the end is about 10 cm deep, in the shape of a dustpan. When the hare hides, it usually only hides the lower part of its body, the back ridge is flat or slightly higher than the ground, and it is invisible by virtue of its good protective color throughout, leaving or fleeing after foraging or being frightened, digging again when hiding, and sometimes using the old "kuni" to hide.
The hare is known for its alert nature, tight concealment, better visual and auditory vision and hearing, rapid escape, strong reproductive ability, and despite its large number of natural enemies, it can still maintain its population longevity. Hare camp day and night life, like to walk on the "rabbit road" (has been walked many times on the fixed animal path), the folk "set rabbit" to take advantage of this feature. It has been active all night since near dusk, and sometimes it has not returned to the nest until dawn. During the spring estrus courtship chase period, there are also cases of activity when there is a cloudy day or drizzle and there are few passers-by [3-4]. On weekdays, only when it is disturbed during the day, it will suddenly escape from its hiding place, but immediately return to the place where it thinks it is safe to dig up a "kunai" to hide. Hare digging "cubes" is extremely fast, usually only takes a few minutes to complete. Hares have a very sensitive sense of smell and chase courtship during the breeding season with an excellent sense of smell. In addition, hares will apply glandular secretions from the nose to the trunk or branches from time to time, or use the odorous gland secretions from the anus to the ground, which is used as a geographical (point) sign, and then identify the way forward by the taste of the secretions. Hares are omnivores, and their food types depend on habitat conditions, mainly nibbling on saplings (young trees), young branches and leaves, bark, shrubs and various crops. It generally prefers to eat the leaves, tender grasses and wild vegetables of trees and shrubs; in winter and early spring, it mainly eats tree branches and young bark, eats grass roots, and occasionally eats lichens, which often causes serious harm to forestry when the population is too large. Hares living near orchards and farmland will eat the trunks of fruit trees at the base of fruit trees, steal vegetables, especially like radishes and newly unearthed bean seedlings in spring, often nibbling in pieces, especially harmful.
In terms of reproduction, the estrus season of male rabbits generally begins in December, but the breeding season occurs sooner or later depending on the estrus status of female rabbits. Mating is usually a number of male rabbits competing to chase a female rabbit, courtship competition is fierce, each other or with the hind legs of the kick, or with the mouth to bite, or with the claw scratch. Mating may also be possible during lactation. Female rabbits mostly give birth in shrubs and next to graves, and sometimes use the nests (holes) of other animals to give birth. The temporary nest is laid with weeds, and the lower abdominal hair is laid on the grass before giving birth to litters. Newborn rabbits are hairy, have open eyes, and can move freely.
Hares give birth to 3 to 4 litters a year, and the mother rabbit will be pregnant in early spring and February. The gestation period is generally 45 to 48 days. 2 to 3 litters per litter in February to March, 4 to 5 litters per litter in April to May, 5 to 7 litters per litter in June to July, the number of litters increases with the month is because it is related to the richness of food and the gradual warming of the temperature. In the event of drought in spring and summer (which is the norm in northwest Liaoning), the survival rate of young pups will be higher, and the number of hares will increase sharply after autumn, and vice versa. In general, after deducting mortality, a single female rabbit can breed 6 to 9 young rabbits in an average of 1 year. The average lifespan of a hare is 8 to 10 years.
Hares have thick fur to withstand the cold, so they can live in the open air. Hares usually moult once in April and October, and in summer the back and buttocks coat color is close, mostly short needle hairs, and in winter, soft villi increase, while long needle hairs are exposed on the side of the body. The hare has developed and strong hind limbs, and can run for 1 to 2 km continuously, and then successfully evade the pursuit of predators. When chased by predators, the hare's escape and avoidance countermeasures are to run quickly and stop intermittently, and the route is tortuous. Its foot movement is characterized by two forefoots arranged in an alternating arrangement anteriorly and anteriorly, with the two hind feet symmetrically parallel. Whether running or jumping, the hare maintains a basic posture, that is, the hind legs are extended to the front legs, using its strong hind leg pedaling force to make the body jump both high and far.
It was observed that hares had 2 different kinds of feces: one that was not normal, called the gastric sac, was a small spherical moist soft feces wrapped in mucous membranes and excreted from the cecum; the other was normal feces, in the form of a regular spherical form (no longer eaten after excretion). The test results showed that the above gastric sac (soft feces) contained 4 to 5 times higher content of V B1 than normal feces, so that the feces can be eaten (swallowed) by hares immediately after being excreted. It is precisely because the hare has this special re-digestion function that it can ensure the key task of survival in the harsh environment of not eating food for a long time.
2 Traditional rabbit pest control technology
In response to the rabbit nibbling disaster, the competent government departments and relevant forest technicians have developed a number of prevention and control measures [2], such as brushing special anti-rabbit gnawing agent or whitening agent plus paprika powder, collecting rabbit feces and urine and adding water to make a paste brush tree trunk, brushing the trunk with animal oil (or fishy odor) with adhesive, sprinkling avoidant (smell avoidance, smell must escape, etc.), applying avoidant (animal blood or bone gel solvent, mutton oil and kerosene or engine oil mixture, etc.), mixing bait trees or planting substitutes (alfalfa or other pastures), Pit digging control or moderate deep planting (sinking 20 to 30 cm deep), afforestation of large-scale seedlings (more than three years old), trunk wrapping of glass silk bags and waste newspapers and hard plastics, etc., creating conditions to attract small predators (owls, eagles, falcons, eagles, snakes, weasels, ocelots, foxes, etc.), burial mound method, setting up wire sets or pullnet covers on rabbit lanes (when the area is large), trapping with rabbit cages and bait (carrots or apples), wicker basket cage method, battery wire shock (commonly used in orchards), Restricted hunting under strict supervision, the release of botulinum toxin or estrogen and sterile agents to kill rabbits, the use of pathogenic microorganisms (bacteria or viruses) to kill rabbits, the application of regulatory forest protectors (GM- and SM-series), etc. In addition, there are also related invention patent authorizations (pig skin + sodium hydroxide + sulfur + lime + diesel) and so on. Practice has proved that the above emergency measures are very necessary and have certain results, which can be summarized into ecological regulation law, biological control law, protection avoidance method, physical killing method, chemical control law, envelope protection law and space barrier protection law.
3 Young tree trunk base nested threaded plastic pipe anti-rabbit gnawing technology
The technical route of rabbit gnawing of nested threaded plastic pipes at the base of young tree trunks is shown in Figure 1.
Figure 1 The Technical Route
In principle, this technology is a physical protection method, but it also meets the comprehensive conditions of "simple operation, once and for all, one-dimensional multi-efficiency, low cost, and environmental friendliness". On the basis of the rabbit bite height survey, the minimum length of the casing is determined. Carry out local tests of single tree species (including comparison between methods) and cross-regional tests of multiple tree species, promote them while testing, summarize experience in a timely manner, and refine the best operation techniques. Use technical training and on-site guidance for large-scale applications. In the process of experimentation and promotion, it was found that in addition to the reliable effect of anti-rabbit gnawing, this method also has multiple functions such as anti-sunburn, anti-frost damage, anti-pest, disease prevention, livestock hazard prevention, drought resistance and water retention, etc., which is of great promotion value. In addition, it is necessary to systematically summarize the research results in recent years and submit them to experts for identification (recognition) in order to lay the foundation for comprehensive promotion.