The great crocus robbery

A common complaint of gardeners at this time of year is the mysterious disappearance of yellow crocus flowers, and the finger of suspicion is often pointed at the local house sparrows. It’s not entirely a coincidence, nor is it undeserved. As spring blossom starts to brighten the garden and attract our attention to the show of fresh colours, so the males of many bird species start to display brighter colours too to attract the attention of females.

Last year’s young blackbirds get their first breeding opportunities and acquire the bright yellow bill and eye-ring that help attract a mate. The coloured feathers of some species also start to look a bit brighter – male chaffinches, blue tits and great tits seem to look just that bit brighter in the spring sunshine, and the male house sparrow’s black bib begins to look bigger and bolder too.

A young male before the breeding season (left) and one in full breeding condition (right).

The reason for all this, of course, is the need for males to demonstrate to females that they are the fittest, strongest and most reliable partners available to ensure the females can raise healthy young. Females are understandably choosy; they want their young to survive to adulthood and so pass on their genes.

The grey tips of this sparrow’s plumage are wearing off to expose the black underneath. Males need a bold bib to impress a female.

The theft of yellow crocus flowers (and my red runner bean flowers later in the summer) is actually an important part of this process. Chemicals contained in red and yellow flowers are known to be associated with an efficient immune system in birds, and also help produce yellow and red plumage. So the female blue tit is looking for the male displaying the finest yellow as he’s likely to be healthy and a good bet for helping with chick feeding.

Just what a female blue tit is looking for: the bright yellow suggests this is a ‘fit’ male, and his bright blue crown possibly means he has a ‘good’ territory with plenty of food.

Another reason for the feathers looking brighter is that the duller tips are wearing away to reveal deeper colours underneath, like the chaffinches pink breast – just when they are needed. It’s why the male sparrow’s black bib is also getting bigger, the dull grey feather ends are wearing away and females are attracted by the best bibs as that is another sign of the owner’s fitness. More daylight hours also stimulate the males to sing. Our resident garden birds have no competition from summer migrants yet, so evenings are full of their territorial song. Some blackbirds, song thrushes and, particularly, robins will sing well into the night if there is a nearby light source. The nightingale that famously sang in Berkley Square was almost certainly a robin: our evening shopping visits to Lidl at this time of year are always brightened by Tovil’s own car park ‘nightingale’ singing its heart out as we struggle with bags to the car (below!).

Finally, a reminder that any necessary trimming of hedges and shrubs should now be done very carefully, and only after first inspecting them to check there are no nests under construction or already in use. All birds are protected by law, along with their nests and eggs, and it is an offence to disturb them once they have started breeding. This includes the humble sparrows – even if they have devoured your crocuses!