Fecundity data for midcontinent sandhill cranes, 2003-2006

Midcontinent sandhill cranes (Antigone canadensis) are the most abundant management population of cranes in the world and have a broad breeding range. Four breeding segments of midcontinent sandhill cranes have been designated based on spatial and temporal distributions throughout the year, including Western Alaska-Siberia (WA-S), Northern Canada-Nunavut (NC-N), West-central Canada-Interior Alaska (WC-A) and East-central Canada-Minnesota (EC-M). WA-S and NC-N cranes primarily are composed of the lesser sandhill crane (A. c. canadensis) subspecies that breeds in the arctic, whereas WC-A and EC-M cranes are composed primarily of greater sandhill cranes (A. c. tabida), birds which breeds in northern parts of temperate and subarctic regions. Existing information on annual recruitment rates come primarily from ground surveys conducted on fall staging areas in Saskatchewan during the 1960s and 1970s. It is unclear whether recruitment rates have changed over the past several decades during a period of a marked increase in harvest and changing climate and land use. More recent data described in the metadata file were used to estimate fecundity of sandhill cranes to parameterize a population dynamics model. The model was developed to evaluate effects of varying harvest rates on population dynamics, including consequences of differential harvest of segments. These data also were used to compare estimates of annual recruitment derived from fall age ratio surveys with those from individually marked individuals.