Fota Frameyard Blog

Gardening, Nature and Heritage from Fota House

A Murder of Crows

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Crows get a bad rap. Is it deserved?  They can be noisy as they gather in large, sociable groups for the evening roost. Farmers justifiably hate them because Ravens can kill lambs or eat seeds and root vegetables. We often attribute human characteristics to birds and animals and in the case of crows we use words like – raucous, aggressive, cheeky, quarrelsome, devious or even call them vermin. To this list we can add more positive adjectives like – intelligent and playful, with the ability to learn how to use tools. Whatever we think of them, they feature large in our lives, whether we live in the city or the country. And Fota is no exception, where they live in the high trees and feed on the expansive lawns.

Rooks flying over the Walled Garden and on the lawn of Fota House

The Corvid family is made up of Rooks, Jays, Magpies, Ravens, Jackdaws, Hooded Crows, Carrion Crows (rare in Ireland) and Choughs. At Fota it’s mostly Rooks that we see.  

The Corvus frugilegu or Rook (Rúcach) is a strong, muscular bird, somewhat untidy looking. Its black plumage can have a purple/blue tint. Comically, it has the distinguishing feature of its ‘trousers’ formed by the thick, thigh feathers on its legs. The adult birds have bare skin around the base of the bill.  Juveniles don’t have this feature, which only develops in the spring of their second year.  

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High-rise rookery at Fota

Rooks build large, untidy nests high up in the trees. From late Winter, early in the New Year, they can be seen breaking off twigs from nearby trees and carrying them back to the rookery, which is like a noisy building site. They can even be seen mischievously stealing twigs from other nearby nests. They like to nest beside other rooks and the colony can look like a densely populated built up high-rise!

The hen lays and incubates the eggs which are smooth, glossy and light blue, greenish-blue or green with dark spots.

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Rooks’ eggs

Both parents feed the young after they have hatched. The young ones fledge after about a month. 

Rooks at Fota can be seen foraging on the grass and they like to eat worms and insects, turning over leaves with their strong beaks. But rooks are opportunists and seem to eat anything that comes their way. They can also be seen carrying crustaceans from the nearby shores of Great Island and dropping them onto the paths to break them open. 

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One of the Fota rooks foraging in the long grass

When the birds come to roost at night they can be seen landing in pairs. It seems that they pair for life, but then their lives can be short.

The species is widespread and abundant in Ireland breeding in all areas, it is only absent from the centre of towns and uplands areas. 

Here is a gallery of some of our rooks:DSC_0327

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In mythology, crows feature a lot. The Norse god Odin used two crows – Hugin and Munin, representing thought and memory – as his daily observers of the world. In Irish mythology, the  goddess Badb features in the story of Táin Bó Cúailnge, taking on the form of a crow or raven  as she causes terror amongst the forces of Queen Medb. We have Aesop’s Fables to tell us  how intelligent and resourceful these birds are. One of the most popular of these is the story of the Crow and the Pitcher. In this story the thirsty crow couldn’t reach the water at the bottom of the jar, and proceeded to fill the pitcher with stones to raise the level so that he could drink. This story was told to demonstrate the moral that “Necessity is the mother of invention”.

But scientist have spent many years studying corvid behaviour in relation to their resourcefulness. The Journal of Experimental Biology describes some of these experiments where corvids not only used tools but also showed the ability to select the correct tool to access a worm in a tube. “The rooks were able to select stones of the right size and shape to fit into the tube, and would also go and get appropriate stones if none were provided near the apparatus. These behaviours indicate that the birds were able to select tools that were functionally relevant to the task. If the rooks were not given access to stones, but instead to a novel stick, all the birds immediately picked up the stick and solved the problem using this new tool. When provided with a combination of a functional stick and a non-functional stone (or vice versa), the birds chose the tool that would enable them to get the worm, reinforcing the interpretation that the functional aspect of the tool was fundamental for their choice.

Amazingly, the rooks were also able to show `metatool use’, in which a tool was used to get access to a tool that would, in turn, gain access to the worm. This reveals that the rooks could recognise that a tool can be used on a non-food item, and that they were capable of hierarchically organizing their behaviour, resisting the temptation to try to get the food immediately. This is something that monkeys find extremely difficult. Success rates in this test were very high – nearly 97% and all birds solved it on the very first trial.

Finally, the authors tested the ability of rooks to make their own tools, either by removing side-branches from a stick, so that it would go into the tube, or by making a hook that would enable them to get the worm directly (the birds had already shown they could use an existing hook to this end). In both cases the birds showed spontaneous tool creation, manufacturing a hook or changing the shape of the stick.” 

While these laboratory experiments show us how intelligent the rooks are, other observations in the wild re-enforce this.  In Norway and Sweden, fishermen make holes in the ice and drop their fishing lines through them into the water. Crows have been seen picking up the line and walking backward as far as they can, pulling the line out of the hole. The crow will do this as often as it needs to bring the end of the line to the surface, as well as the bait or the hooked fish. 

But the best way to get to know these fascinating birds is simply to observe them. It’s easy to do this because they are everywhere, they are loud and large and while generally wary, they’re not shy and don’t let human activity interfere with what they do. They simply are themselves, whether you like them or not. One afternoon as a group of us walked back from the Frameyard, we were watching at a large group of rooks on the lawn and one volunteer remarked “Sometimes I think they’re the Smith-Barrys” and it’s easy to see what she meant. These rooks own the place, perching proudly on the tall trees and chimneys and strutting in their fine feathers across the lawn. But it’s a nice idea to think that the Smith-Barrys are still around, keeping an eye on us as we work to preserve their heritage at Fota. 

 

Photo of rooks’ eggs: http://birds.nature4stock.com/?cat=1&paged=26

References:

science.jrank.org/pages/1886/Crows-Jays.html

http://jeb.biologists.org/content/212/17/v.2

http://www.birdwatchireland.ie/IrelandsBirds/Crows/tabid/403/Default.aspx

https://www.irelandswildlife.com/know-crows-identify-corvids-bto/

 

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Author: fotaframeyardblog

We are volunteers who work at Fota House Frameyard in County Cork, Ireland.

2 thoughts on “A Murder of Crows

  1. Great piece. And yes, they do get a bad rap!

    Like

  2. This is a particularly brilliant feature, and the photos of rooks at Fota are simply breathtaking in their precision.

    Like

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