It’s the time of year when we buy, and send, Christmas cards and there is a wide selection to choose from. A common subject is the European robin (Erithacus rubecula), that first appeared on cards in Victorian times and which achieved popularity by association, postmen of the time wearing red coats [1, 2]. Those of us with long memories remember the pleasure that letters from loved ones could provide, with the postman/postwoman as the agent of that pleasure. Their visit was sometimes keenly anticipated.
Robins have been named by UK residents as our favourite bird. They appear to be friendly, approaching close by when we are gardening, and we enjoy the idea that “our” robin comes back each year to maintain the friendship. However, their interest is opportunistic, as they are looking for food that gets turned up, rather than wishing to make contact with us, and the friendly bird we know year on year is not always the same one. Although a robin has been recorded to live for 11 years, most die within a “couple of years” [3], and, for some reason, cards with images of dead robins (and other small birds) were popular in Victorian times (see below for a well-known example).
Robins are unusual in holding of a territory throughout the year, with a male and female sharing a territory during the breeding season [4]. Territories are defended by singing and, if necessary, by fighting, and the scene shown on at least one design of Christmas card is very unlikely, as adult robins in such close proximity would certainly result in challenges that could lead to death of a participant in a fight.
The life of robins set me thinking about longevity in birds of various species and I found two interesting papers on the subject that use data from ringed wild bird populations. Placing rings on birds’ legs enables recorders to determine their range, and the distances that they fly, and, understandably, there are more records for common short-lived birds than for less common long-lived birds [5]. Nevertheless, Lindstedt and Calder showed a positive correlation between longevity and body mass of birds of a wide range of species in North America. They further showed that, on average, captive birds lived longer than wild birds, the latter facing greater challenges in finding food and coping with climatic conditions. The longest-lived wild bird (recorded at 37 years) is an albatross [6], with a captive cockatoo living for 80+ years, although the records for many large wild birds are likely to be eclipsed once we have more ringing returns.
A further study by Sæther [7] confirmed the positive relationship between survival rate and body mass in natural populations of European birds, so it is no surprise that the European robin, being a small bird, is short-lived and produces large numbers of offspring to compensate for this mortality rate: larger birds, on the whole, are likely to produce fewer offspring. Perhaps Victorian Christmas card designers knew more about the mortality of robins than most of us do today?
[2] https://scottishwildlifetrust.org.uk/2019/12/why-do-we-associate-robins-with-christmas/
[3] https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/robin/threats/
[4] https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/robin/territory/
[5] Stan L. Lindstedt and William A. Calder (1976) Body size and longevity in birds. The Condor 78: 91-94.
[6] https://web.stanford.edu/group/stanfordbirds/text/essays/How_Long.html
[7] Bernt-Erik Sæther (1989) Survival rates in relation to body weight in European birds. Ornis Scandinavica 20: 13-21.
