Bird Tracks (eBook)

INTRODUCTION

BIRD TRACKS FOR TRACKERS AND BIRDWATCHERS

Collared Dove tracks.

As naturalists and trackers, we stare at a lot of mud and sand and dust, picking out the tracks to tell the stories of (most often) the mammals that passed by. This gives us an intimate understanding of their day-to-day lives even when the animal is long gone. Birds leave their tracks in these same places and – naturally – we want to be able to read their stories too. However, what we found with the bird tracks we were seeing was that we always came away with questions. Either we couldn’t identify a track because the available books didn’t help, or we were looking at a track we thought we knew – like Blackbird or Carrion Crow – and wondering what the difference was between this track and that of a Song Thrush or Rook, and again the books couldn’t help.

So, this book came about principally to try and answer a question. What birds can be identified accurately to species level using only their tracks? Various publications in a number of countries have looked at bird tracks, and they have all helped to reveal the answers for some species, but none of them – in our view – have looked at the full range of birds of the British Isles and northern Europe in the kind of detail that we needed, and which we have attempted to present here.

Unlike our other mammalian friends, birds are easy to see and call or sing frequently, so the best way to discover which birds are in an area is by watching and listening, and that will always be the case. But, birds do leave tracks (and signs, such as feeding signs, feathers, nests and egg shells) that sometimes show us new things about the species (how it moves, what it’s eating, where it’s moulting and nesting), and occasionally give away their presence when we haven’t seen or heard them. For example, the tracks of nocturnally active birds (such as Owls, Woodcock, Stone-curlew, etc.) can reveal their occurrence, feeding habits and ecology during daylight when they are no longer active or even present. Waders in particular often use different sites to forage during the night, to roost at high tide or as traditional moulting areas (see Burton and Armitage, 2005, as an example), and tracking can help us discover those sites.

Tawny Owl tracks.

In addition to seeing and hearing birds, bird tracks are part of the evidence picture (along with other signs) and in this respect they enrich our understanding of what a species is doing, how it is living, and therefore also help strengthen our appreciation of that bird. It seems that within the birdwatching and ornithological community there is very little use of bird tracks and signs, and we feel that some might be missing out on an integral part of the story.

Stone-curlew museum specimens.

As trackers, we know that obvious features of the feet of certain birds allow us to make an accurate, species-level identification, but we wanted to see how far this concept could be taken. Would it be possible, for example, to tell Great Tit tracks from Nuthatch tracks, or House Sparrow from Chaffinch. With this question in mind, we also recognise that many species rarely spend much time on the ground, and still more are so small and light that they seldom leave tracks when they do venture down. Therefore we can ask the question: if a certain species only leaves infrequent, very hard-to-identify tracks, how useful is that knowledge in the real world? However, in exploring how far we can take bird track identification, we have looked for minute differences between tracks and studied their morphology in detail and feel we have shed some light on what is possible, what is not, and what may (or may not) have utility in the field. We are firm believers that tracking is about finding wildlife not just tracks, so utility is key!

COLLECTING TRACKS AND GATHERING DATA

We started this bird track journey with lots of questions that the available literature could not answer for us. It was clear that we needed to gather first-hand data and find tracks for which we were 100 per cent positive of their identification. This meant taking a number of approaches.

Firstly, we did a lot of birdwatching! Watching birds along rivers, at puddles, on beaches and then searching for their tracks. Where there were birds but no tracking substrate, we set out track traps of sand (mostly of children’s play sand, which is preferred because it is non-toxic), clay or anything really that would take the tracks of a bird. We placed track traps under bird feeders in gardens, out in the woods, by lakes – indeed, anywhere where we thought we had a chance of witnessing a bird landing. We then sat, watched and waited for birds to land, at which point we would rush out immediately before the tracks spoiled or got confused with another species.

We were lucky enough to gain access to some captive birds including Birds of Prey, Owls and Waterfowl. Waterfowl, in a private collection, were enticed across sand with the promise of food – the trick here being to try and do it one species at a time! In the case of the Birds of Prey and Owls, these were encouraged by their handlers to land on and move across track traps. The tracks were then photographed. We have also spent some time making plaster casts of the tracks, which gives yet another medium to study the accuracy of our findings.

We looked at and photographed the feet of birds in the hand (mistnetted under license for the purpose of ringing), and also the feet of museum specimens (at the British Natural History Museum in Tring). The museum specimens were useful in helping interpret what we were seeing in the tracks, determining the proportional length of toes, toe pad arrangements, length of nails, etc. They were also helpful for answering questions such as which species (Waders, Ducks, Gulls, etc.) have a Hallux and which do not? Is webbing present or not? Where does the webbing start and finish? That said, the dried-out feet of dead birds can’t be used to anticipate what a track from the living bird would look like, so we have only used this information to interpret or confirm what we were seeing in the field.

Little Tern museum specimens

A variety of track casts

Track traps

Comparing a track cast and its impression.

Studying the feet of a captive White-tailed Eagle

Sand and clay around bird feeders to capture tracks

Track traps

Captive Birds of Prey helping us with track research.

We have referred to all the available published sources, a selection of which are shown below. Occasionally the photos published therein have proven very helpful, and some of them are reproduced (with permission) here. Where we have struggled to find the tracks of certain species (primarily those that are more common in mainland Europe than here in Britain) we have requested track photos from other trackers, all of whom we would like to thank wholeheartedly for their generosity (and all of whom are listed in the Acknowledgements).

Blue Tit in the hand.

Bird tracks literature.

TRACK DRAWINGS

All the drawings in this book have been drawn electronically on a tablet using the free app Sketchbook. Essentially, they have been traced from track photos – following their features and shadows precisely. The app allows for multiple photos to be used (in separate layers), so each drawing is (most often) a composite of features from multiple track photos. One single track photo rarely shows all the features that we ideally want to illustrate, so merging features from multiple photos has hopefully created an accurate ‘average’ representation of a particular species’ track. What becomes clear when tracing track photos is that even tracks from the same individual bird in the same substrate can present differently, with toe angles varying dramatically and features (such as nails, toe ends, Hallux, Metatarsal pad) showing and not showing. In spite of this, we have tried to show the most common presentation in the track drawings. It’s worth keeping in mind, however, that the fewer photos we have had to work from, the greater the chance that the drawing might not be the perfect average we were striving for.

Perfect image of a Blackbird track.

A few brief words about track photos. If you ever decide to draw animal tracks from photos you will quickly find that the quality of the photo is paramount. A good track photo requires a good track – a track that is in substrate that holds the details and is not too deep. The photograph needs to be taken from directly above the track, ideally in neutral light (with not too much strong shadow). And a scale of some sort in the photo (ideally a ruler) is essential.

ANALYSING BIRD TRACKS

CONTEXT

Before getting too absorbed by the actual features of the track you’ve found, it is worth zooming out to a landscape level and refining your list of suspects that are likely in your location, the habitat you’re in and the time of year. Many species are very specific in their preferences, and this may vary regionally and seasonally. For example, Curlew tracks are frequently encountered in upland areas and also can be found both on the coast and in fields. Where John grew up in north-east England, he frequently spotted Curlews on boggy farmland, not somewhere he expects to find them now in his adopted south coast county of Sussex. Many species are also migratory and may not even be in the country at the time you...