Individual study: Supplementary food shows mixed effects on fledging success and survival in Florida scrub jays Aphelocoma coerulescens in scrubland in Florida, USA
Reynolds S.J., Schoech S.J & Bowman R. (2003) Diet quality during pre-laying and nestling periods influences growth and survival of Florida scrub-jay (Aphelocoma coerulescens) chicks. Journal of Zoology, 261, 217-226
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Provide supplementary food for songbirds to increase reproductive success
A randomised, replicated and controlled cross-over trial in a dune and scrubland system in Florida, USA, in 2000 and 2001 (Reynolds et al. 2003), found that that 21 female Florida scrub jays Aphelocoma coerulescens provided with high-fat, low-protein (HFLP) supplementary food and 21 females provided with high-fat, high-protein (HFHP) food laid significantly larger clutches than 55 control females in 2000 but not 2001 (2000: approximately 3.7 eggs/clutch for HFLP diets, 3.2 eggs/clutch for HFHP and 2.8 eggs/clutch for controls; 2001: 2.7 eggs/clutch, 3.1 eggs/clutch and 2.8 eggs/clutch respectively). This was due to earlier laying, discussed below. Clutches on the HFHP diet had a tendency to have larger third-laid eggs, but other eggs were not significantly different in size between treatments. Feeding began in early- or mid-January and continued until females began laying, usually six to eight weeks later. Food consisted of food pellets containing 19.3% fat and with a protein content of either 3.5% or 34.5%.