These berries, belonging to the yellow cultivar of holly Ilex europaeus 'bacciflava', are the only berries left in my garden after weeks of freezing weather. All the scarlet holly berries disappeared within a week of the first snowfall, along with all the other red berries, but the birds have completely ignored these yellow fruits. As far as I can tell, they haven't eaten a single berry.
Birds' vision is much more sensitive to the red end of the spectrum (bird-pollinated flowers are almost always red) and it's tempting to speculate that these yellow fruits simply aren't visible to the blackbirds and thrushes that stripped all the other berries. But I'm sceptical about so simple an explanation. They quickly find and eat the blueberries that I try to grow in autumn, which reflect light at the short-wave blue end of the spectrum, and yellow berries are much closer to the red end of the spectrum. So maybe there's something else that makes yellow holly berries unappealing to birds, even when they are on the verge of starvation in a winter such as this..........
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