Hugh Boyd ( editor ) Population modelling and management of Snow Geese Occasional

Pop u la tions of Lesser Snow Geese Anser caerulescens caerulescens in the mid-continent of North America have increased to the point where they are causing serious damage to some Arctic coastal eco sys tems. A recent modelling exercise by R.F. Rockwell and col leagues (referred to as the Original Model) suggested that increas ing harvest rates of adults to approx i mately twice the average level in recent years would lead to negative pop u la tion growth and hence (under certain assump tions) be suf fi cient to control the pop u la tion. However, some of the param e ters in their models appear to have been inap pro pri ate. Based on revised param e ters, which are con sis tent with analyses of recent data, we suggest that an increase of 3.0to 7.3-fold in the harvest, relative to the same period analyzed in the Original Model, would have been required to reduce pop u la tions at the desired rate in 1994. Despite recent increases in harvest, we predict that a further increase of 2.1to 4.7-fold, relative to the estimated harvest for 1997, would be needed in 1999 to achieve this pop u la tion reduction. Wildlife managers need to be aware of these larger targets when con sid er ing appro pri ate measures to control the pop u la tion. Given the uncer tain ties in many parameter estimates, further modelling, combined with ongoing mon i tor ing of pop u la tion size and demo graphic param e ters, will be required to evaluate and refine any man age ment actions.