Peck on some­one your own size! How big­ger birds rule the roost

Daily Mail - - News - By Vic­to­ria Allen Sci­ence Cor­re­spon­dent

IT hasn’t got ter­ri­fy­ing talons, a flesh-rip­ping beak or an enor­mous wing­span.

But the lit­tle spar­row is the big­gest bully in the gar­den – if you’re a blue tit.

Even though there is barely an ounce in weight be­tween them, the spar­row uses that tiny weight ad­van­tage to rule the roost over more del­i­cate ri­vals.

In fact sci­en­tists have dis­cov­ered that size dif­fer­ence – how­ever slight – gen­er­ally gives an air of su­pe­ri­or­ity when the feath­ers start fly­ing over the tasti­est morsels on the bird ta­ble. In the peck­ing or­der of gar­den vis­i­tors, bul­ly­ing house spar­rows and green­finches get the prize bird food such as easy-to- eat sun­flower hearts, a study by Ex­eter Univer­sity found.

Smaller birds, in­clud­ing blue tits, chaffinches and coal tits, are forced to eat tougher, lower qual­ity seeds. De­spite be­ing just two thirds of an ounce (18g) lighter than a spar­row or green­finch, these smaller birds are forced to peck faster and fly away more quickly to avoid a fight.

Ex­perts say the find­ings could help de­sign gar­den bird feed­ers that would ben­e­fit all species. Se­nior study au­thor Pro­fes­sor Jon Blount said: ‘Our find­ings show that larger, heav­ier species get bet­ter ac­cess to food – so if the aim of bird feed­ers is to ben­e­fit all species, we need to in­ves­ti­gate ways to achieve this, such as dif­fer­ent mixes of foods and feeder designs.’

It is es­ti­mated that three-quar­ters of home­own­ers leave out food for wild birds. Work­ing with the Bri­tish Trust for Or­nithol­ogy, re­searchers stud­ied ten types of perch­ing birds at feed­ers in Corn­wall for al­most a month. They were able to de­ter­mine the most dom­i­nant birds by record­ing 816 com­pet­i­tive in­ter­ac­tions be­tween species at feed­ers.

The bul­lies were gen­er­ally big­ger, in­clud­ing spar­rows, green­finches and nuthatches, and won the best ac­cess to pop­u­lar sun­flower hearts. Less dom­i­nant smaller birds, in­clud­ing coal tits, dun­nocks and chaffinches, more of­ten ended up with harder-to-eat black sun­flower seeds.

Big­ger birds were able to spend more time at feed­ers and peck at a lower rate than smaller ri­vals – which were forced to fly away if they met dom­i­nant birds be­cause of the risk of be­ing in­jured or wast­ing en­ergy on a fight, the study pub­lished in the jour­nal PLOS One found.

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