BIRD POPULATIONS - Birdpop.org

IS AVIAN BREEDING SUCCESS WEATHERING THE STORMS?lower than predictions made using data fromprevious years. Robin, Dunnock and Wren,appeared to be particularly badly affected,exhibiting reduced clutch and brood sizes andincreased failure rates, as did Reed Warbler. It isinteresting to note that ringers participating inthe Constant Effort Site scheme (CES,www.bto.org/goto/cesnews.htm) also reportedlower proportions of juveniles of these species intheir catches in 2007. CES and NRS results werenot in agreement across the board. Nestrecorders found little evidence for the reductionin productivity of Blue Tit and Great Titapparent from the former data set. This discrepancysuggests that weather conditions mayalso have influenced post-fledging survival andillustrates the importance of combining a rangeof techniques when investigating trends in aviandemography.THE IMPORTANCE OF BEING TREND-YWhile the annual fluctuations in breedingsuccess provide a fascinating insight into theprocesses that determine the number of offspringthat birds are able to produce, it is the long-termtrends in productivity that are of greatest use toconservationists. The NRS Concern Listhighlights those species that have demonstratedrecent declines in both abundance and someaspect of productivity (Fig 1). While no newspecies have been added as a result of the latestanalyses, a recent increase in mean brood sizes[137]