- Criticises the approach advocated by DelGiudice (1996) in assessing animal condition from the urea nitrogen:creatinine (UN:C) ratio from ungulate urine in snow. There are problems of actually defining condition, nutrition and stress, and high urea-nitrogen in fact may indicate good forage or advanced starvation. The UN:C index has not been validated against the true parameter (condition) that it supposedly reflects, and even if we accept the validity of this index large variation in the population will require large sample sizes to detect critical differences. G.D.DelGiudice, M.R.Riggs, I.D.Mech and U.S.Seal (pp 698-70) reiterate their views, and emphasising that the degree of winter nutritional restriction will have the major influence on shape and scale of the UN:C curve of winter-pastured wild ungulates. Monitoring techniques are not at present intended to yield precise estimates of percent body mass loss and fat depletion.