PEI wildlife leave all sorts of signs that they’ve been around: tracks, scat, dens, nests, and feeding spots, among others. Some of my favourites are bird pellets: coughed-up bundles of stuff the bird couldn’t digest. It may sound gross, but it’s actually quite useful for both birds and researchers.
Owl pellets (Photo 1) are probably the most famous, but Owls are by no means the only birds to have them. All birds of prey – including Eagles, Hawks, and Falcons – produce pellets, as do Herons, Gulls, Terns, Cormorants, Kingfishers, Swallows, Shorebirds, Crows, and Ravens (Raven pellet, Photo 2). Although meat-, fish- and insect-eating birds are the ones most likely to eject pellets, virtually all birds can from time to time.
Without teeth, birds are left to tear their food into bits small enough to swallow or just swallow it whole. Hydrochloric acid, the digestive enzyme pepsin, and slimy mucus (collectively called ‘digestive juices’) work together to start softening the food before it’s pushed along to the gizzard. The gizzard is a muscular part of the stomach that acts a bit like our teeth. With the help of grit picked up by the bird, the gizzard grinds food into smaller pieces so digestive juices can break it down even further.
Unfortunately for the bird, the gizzard does an incomplete job on teeth, bones, fur, feathers, and some of the tougher plant material. Teeth or bones could tear the bird’s intestines; fur, feathers and tough plants could cause a blockage – either of these situations could be fatal for the bird. For this reason, birds’ digestive systems are adapted to be able to compact this indigestible material and send it back up and out the mouth rather than through to the other end.
Pellets from Ravens and Raptors (birds of prey) are larger and more tightly packed than those of other birds and so they are both easier to see and longer-lasting in the environment. As a result, they are the pellets most commonly found. Although the pellets shown here are roughly the same size, Owls are strictly carnivores and theirs will contain only teeth, bones, fur, or feathers. Ravens are omnivores; their pellets may have some animal material but more often will be mostly tough, indigestible plants and seeds. You can see bones sticking out of the Owl pellet and plants in the Raven pellet.
Bird pellets are both useful and fun! Researchers use pellets to learn more about the diet of the birds that left them and the ecology of the area. Pellets can reveal not only what the bird has been eating, but also information about its prey (for example, changes in the abundance of certain prey in the pellets point to changes in those populations in the environment). Additionally, dissection of bird pellets is a fantastic educational tool for kids (ok, adults too!). While finding pellets ‘in the wild’ can be challenging, you can purchase kits that come with both pellets and guides to help you pull them apart and identify the contents.
Bird pellets are another cool part of PEI untamed!
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