Consistent with other evidence of global warming, birds in the UK are laying eggs earlier in the year, scientists at the British Trust for Ornithology have found. Their new study is one of the first to show long term changes in the ecology of many species simultaneously, according to the ENDS Daily news service. Of 65 species studied, 20 showed a statistically significant trend towards earlier laying over the 25 year period 1971-1995, while only one laid significantly later. The study follows other recent work showing that the growing season of plants in the northern hemisphere is beginning earlier. Food availability is one of the main factors affecting egg laying and earlier leaf-break leads to more insects, meaning more food for birds.