One of topics commonly discussed in corvid fora and question frequently asked is what to feed crows, usually referring to birds in the wild, but also to birds cared for in captivity or during rehabilitation. One of the most frequent answers given is that the name carrion crow is a giveaway, and that crows would eat, who would have guessed, almost exclusively any type of carrion.
However, when looking through findings of scientific studies about feeding habits of corvids, confirmed and enriched by individual experiences of corvid rescues and rehabbers, it becomes evident that this answer is not exactly true and would in fact suggest an unhealthy and unbalanced diet.
Jack is a two year old imprinted jackdaw, who came to us in March 2017, having shown deficiency signs at the time of admission caused by an insufficient diet. Jack has been raised by his own and kept in a cage with occasional indoor free flight after being found as an orphan. It was only last year, when he has been joined by a fledgling carrion crow. Jack has also suffered of a condition called cross, crooked or scissor beak, in which the top and bottom beaks do not align properly. This can be caused by genetics, an injury or the inability to maintain the beak’s length and shape by normal honing on rocks or other hard surfaces. It is also thought that an improper hand feeding technique and an unbalanced diet play a role in the development of this beak deformity.
A scissor beak needs frequent trimming, which has been done in Jack’s case carefully and gradually in several short sessions to allow the beak to regrow and reshape into a ‘normal beak’. However, this is not always possible and the success as well as relapse rate depends on many factors. In Jack’s case this has been achieved and the beak is now ‘maintenance free’ for more than three months. Apart from a balanced diet, it is also important to provide any bird with the means to ‘use’ the beak sufficiently, to enable the bird to strengthen the facial muscles and to allow natural wear and tear. Rotten tree stems, pebbles, bricks, rocks, shells, wooden toys, cuttle fish bone and marrow bone dog biscuits are only a few of suitable toys and tools, which help to keep a beak in a good shape and a jackdaw well entertained. Achieving the ‘perfect’ shape of the beak through trimming is obviously important and the prerequisite to solve the scissor beak problem. However, if a scissor beak persist for long, muscles will get atrophic, meaning they become shorter than normal, which can pull even a well shaped beak out of alignment resulting in the beak to continue to grow in an asymmetric fashion. This is why all beak trimming sessions do also involve some degree of physiotherapy to counteract problems caused by muscle atrophy.
Although corvids are generally known as scavengers and omnivores, the diet of the different corvids species does vary considerably, from species to species, and over the seasons of the year. Only about 40% of the rooks’ diet for example consists of animal protein, and those being mainly worms, bugs and larvae. They usually don’t eat carrion, as their beak is not designed and able to rip animal carcasses into manageable pieces. The remaining 60% of the rooks’ diet are plant-based products like fruits, seeds and vegetables. During the winter time, carrion crows prefer seeds, berries and carrion, whilst during the summertime they do mainly live on animal protein like snails, worms, insects, small mammals and eggs.
Hatchlings And Nestlings Up To 3 Weeks
When raising hatchling corvids it is important to feed a purely insect based diet for the first two weeks of their lives. Ideally these birds should be fed on an insect mash consisting of the following ingredients:
Frozen fresh insects like crickets and wax worms
Mineral and vitamin mixture like Korvimin ZVT+Reptile (WDT)
Small amounts of feathers and fur should be added to the mash occasionally, but only when the bird is older than 2 weeks, which will help to produce pellets
Alternatively one can also create a baby food mixture (Modified recipe, original recipe by Samantha Bedford of Bedfordshire Wildlife Rescue) based on the following ingredients:
2 parts ground up (80%) chicken biscuits (Applaws Kitten Food Chicken)
1 part Hagen Tropicana Breeding Mash
1 part Heath’s Prosecto Insectivorous Soft Food
Dried ants, flies and daphnia
Korvimin ZVT+Reptile by WDT (Nutrobal for Birds by Vetark)
Bene-Bac Powder for Birds and Reptiles by PetAg (AviPro Plus by Vetark)
Nestlings Older Than 3 Weeks
When the bird turns 3 weeks, we would start reducing the amount of mash and introduce soaked cat biscuits in addition to the mash fed, which are of an ideal consistency and therefore easy to use for hand feeding. GoCat Chicken and Duck Complete pet food for adult cats (Purina) is well suited for corvids, as it provides the needed high protein contents required. It contains 20% rehydrated meat and animal derivatives, with a minimum 4% chicken and 4% duck (30.0% protein, 10.0% fat content). Tinned dog or cat foods are not a suitable diet for corvids and will most likely cause diarrhoea.
When the birds have fledged, a broader variety of food items will be added to the daily corvid menu, which will be provided in addition to hand feeding in a dish to encourage self feeding. Food will be supplemented with Korvimin ZVT+Reptile by WDT (Nutrobal for Birds by Vetark) to avoid a calcium deficiency. Alternatively one could also grind thoroughly cleaned empty snail shells, which make a good cheap, natural and easily digestible calcium supplement. The basic diet plan for all corvid species consists of:
Soaked cat biscuits (GoCat Chicken and Duck Complete pet food for adult cats (Purina)
Vegetables (fresh corn or maize, corn on the cob or peas)
Fruits (berries, grapes, apple or pear)
Scottish Rough Oatcakes
Good quality bird food seed mix enriched with peanuts, suet pellets and dried meal worms
Live meal worms (larval form of the mealworm beetle – tenebrio molitor) and wax worms (larval form of the wax moth – galleria mellonella)
Dead or frozen fresh insects like crickets, calci–worms (larval form of the black soldier fly hermetia illucens) or natural pinkies (larval forms of bottle flies)
Hazelnuts or walnuts for jays
Occasional food items in particular for crows include dead mice, day old chicks, raw pigeon eggs and cuttle fish bone
Worms and snails must not to be fed to corvids, although being part of their natural diet, as they are carriers of coccidia and worms. Although birds are being encouraged to feed themselves, assisted hand feeding needs to continue until the birds are completely weaned. Fledglings should also be moved into a suitable and spacious aviary, where they can learn to forage and are able to cache food.