Flux and Flux: Population Dynamics and Age Structure of Starlings

At Belmont, Lower Hutt, a population of starlings which nested in 500 nest boxes on 1500 ha of pasture land was studied from 1970 to 1979. In total, 750 breeding females and 60 males were individually banded, and of 4006 chicks that Hedged 258 females returned to nest in the study area. In different years, 3-60% of the females attempted a second clutch after a successful first brood. Clutch size of females more than 1 year old averaged 4.48 eggs (4.17 to 4.81 in different years) and declined seasonally in early (4.57), intermediate (4.40) and late clutches (4.06). On average, individual females laid 4.17 eggs per clutch in their first year, reached peak clutch size of 4.77 when 3 years old, and declined steadily to 3.9 eggs at 8-10 years old. Productivity was low: 33 % of 17 326 eggs laid produced young likely to have fledged, equivalent to 1.63 chicks per box available or 1.92 per occupied box. The annual mortality rate of starlings banded as young was only 33% in New Zealand as a whole, compared with 50-70% overseas.