Constant companions: Wild zebra finch pairs display extreme spatial cohesion

Many animals maintain long-term monogamous partnerships, but the extent to which partners interact varies substantially and has implications for the scope of cooperation between pair members. Zebra finches are monogamously paired for life, raising questions as to if and how they maintain pair cohesion in the absence of having territories and in the absence of long-range signals. While zebra finches are the best studied songbird in captivity, their social and spatial behaviour in the wild is poorly understood. Determining pair cohesion in songbirds to date has almost exclusively been studied only at specific locations, such as nesting or feeding sites where bird presence can be logged incidentally, without quantifying broader movements. Here, we used automated tracking to continuously monitor the movements of radio-tagged zebra finch pairs during a period with breeding activity. We reveal extremely high pair cohesion with pairs using nearly identical home ranges and maintaining close spatial proximity throughout the day. This characterisation of extremely high spatio-temporal coordination of zebra finch pairs provides novel and important insights into the operation and benefits of monogamous relationships in highly mobile taxa, such as birds.