Blood parameters provide little information that can’t be gained from gross examination of the carcass. Gross examination of birds dying from malnutrition or starvation is sufficient for a diagnosis providing other disease entities are investigated and ruled out.
Prevention Supplemental feeding of starving wildlife is an alternative to allowing wildlife species to die. This, however, involves a philosophical question of maintaining wildlife populations at a level above their normal carrying capacity, interfering with nature’s checks and balances on populations and encouraging transmission of diseases (bovine tuberculosis). It may also be cost prohibitive. If a feeding program is to be used to maintain a high plane of nutrition it needs to be started early in the winter, continued throughout, and a surplus of food must be provided. If food is not provided (especially in ruminants) until malnutrition is in its advanced stages, the animal will probably die anyway. This is because once food is made available, the ruminant must be able to live in a negative energy balance for up to 2 weeks, before its digestive tract can adjust to the new diet and change to a positive energy balance.
Generally, starved ruminants do not eat large quantities of food when sudden access to unlimited food occurs. However, due to an altered microbial population in the stomachs, it is possible to observe mortality in deer when shelled corn is overeaten. The reason for this is that lactic acid from the fermentation of starch accumulates to toxic levels. High quality palatable feed is essential in a feeding program: feed which contains readily available carbohydrates, roughage, minerals, and vitamins. Pelleted formulated feeds are the best ration that can be provided for ruminants. Elk can survive on high quality second or third cutting alfalfa but deer have greater difficulty in obtaining adequate energy from roughages like this that are high in fiber. If baled hay is all that is provided for deer, it must be high quality alfalfa fed at a level where the deer do not have to consume anything but the leaves and small stems.
Supplemental feeding of birds is usually only done for songbirds but does occur with waterfowl species and turkeys under certain circumstances. The feeding of waterfowl during the winter may encourage alterations of normal migration patterns and possibly be of disease importance. Avian species respond faster to the providing of food once physical condition has been affected. Consequently, if the necessity arises, supplemental feeding can be started at anytime and probably be successful.
The plane of nutrition animals are on in the winter influences the severity of mortalities due to starvation, the reproductive success of the females, and the animal’s resistance to disease, parasitism, and predation. Deaths attributable to starvation may have a great and persistent effect on a population, not only due to the loss of individuals, but also due to the disruption of fertility and reproductive success.
In mammals, the effects of starvation on a pregnant female and her fetus(es) may be seen in utero, or after birth. Pregnant females catabolize their own fat and protein reserves during periods of food deprivation. The fetus is protected by these actions and continues its development. If a pregnant female is forced to withstand prolonged malnutrition, however, the fetus may die and be resorbed or aborted. A fetus that is not resorbed or aborted, but survives and continues its development to term, may be born small and have a reduced chance of surviving. This is especially true if malnutrition occurs during the third trimester of the pregnancy. These small offspring will probably have difficulty in suckling and the female may not permit them to do so, thus rejecting them. It is, however, possible that a malnourished pregnant ruminant will maintain its pregnancy until it dies from starvation.
The ability of the malnourished animal to resist bacterial and parasitic infection is markedly reduced when the body’s immunological system has been compromised by the animal’s malnourished condition. In conclusion, malnutrition and starvation can be significant influences on a population of animals, but usually this effect is short term and the population returns to its normal level.