THE MONITORING AVIAN PRODUCTIVITY AND SURVIVORSHIP (MAPS) PROGRAM 2002 AND 2003 REPORT

DeSante, David; Kaschube, Danielle

This report summarizes results of the Monitoring Avian Productivity and Survivorship (MAPS) Program during 2002, when 505 stations were operated, and 2003, when 456 stations were operated. Changes in adult population size and productivity (i.e., reproductive index, defined as young/adult) between 2001 and 2002 and between 2002 and 2003 were derived from constant-effort data from 417 and 349 stations, respectively. Adult population sizes increased significantly in 2002 at the program-wide scale and, with varying significance, in each of the seven MAPS regions except the Alaska/Boreal Canada Region. In contrast, productivity in 2002 decreased significantly at the program-wide scale and in all regions except the Alaska/Boreal Canada and South-central regions, where it tended to increase. The patterns of changes in both adult population size and productivity in 2003 were nearly exactly reversed from those in 2002, with substantial and generally significant decreases in adult population size program-wide and in all regions except the Alaska/Boreal Canada and South-central regions; and a significant increase in productivity program-wide and increases of varying significance in five of the seven regions. These generally alternating, out-of-phase patterns in productivity and population size have been characteristic of MAPS data for many years and suggest density-dependent population regulation in which (a) increased productivity in a given year leads to increased population sizes the following year through increased recruitment of young birds, and (b) the increased population sizes suppress productivity through increased competition for food or other resources needed for reproduction. That these patterns of changes have not been consistent in all regions in all years suggests that density-independent factors may also drive changes in productivity and that other factors besides productivity (e.g., survival of young and adult birds) also drive annual changes in adult population size. We used modified Cormack-Jolly-Seber (CJS) mark-recapture analyses, with ad-hoc betweenand within-yr transient models, on 12 years (1992-2003) of data pooled from 550 stations operated for at least four consecutive years to estimate program-wide and regional annual adult apparent survival and recapture probabilities and proportions of residents among newly captured adults for over 180 species. The mean number of stations per region contributing data (79) and mean number of species per region for which survival rates could be estimated (62) were 15% and 5.4% greater, respectively, than the analogous means (68 stations and 59 species) for the previous 10-yr (1992-2001) analyses. The increased number of stations and years of data resulted in continued increases in the precision of survival estimates: the mean number of species per region with CV(survival)<30%, <20%, and <10% increased by 11%, 11%, and 31%, respectively, using 12, rather than 10, years of data. As in previous years, a pattern was detected in which mean regional adult survival rates decreased with increasing latitude; they also were higher for the two western regions, lower for two eastern regions, and lowest for the two central regions. For each of the seven regions, survival estimates for species for which CV(survival)<30% were lower for the 12-yr (1992-2003) than 10-yr (1992-2001) data set, continuing the pattern noted in previous reports and suggesting that survival has been decreasing in each region. For all species pooled at the program-wide scale, we used (a) chain indices to estimate a highly significant 12-yr (1992-2003) decline in adult population size of -1.86% per year, and a widely fluctuating temporal pattern in productivity with a decreasing tendency of -1.02% per year; and (b) both time-dependent and linear trend CJS models to estimate a significant 10-yr (1993-2002) decline in adult apparent survival of -0.83% per year. These declines in vital rates will...

THE MONITORING AVIAN PRODUCTIVITY AND SURVIVORSHIP (MAPS) PROGRAM 2002 AND 2003 REPORT

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