The bird with the silvery eyes

In his most amusing book King Solomon's Ring, Konrad Lorenz described his experiences rearing a veritable menagerie of different animals including jewel cichlids, water shrews, a raven, cockatoos geese and ducks. His intention was to develop an intimate relationship with them and understand their behaviour and communication. He reared the birds himself then set them free. This allowed him to have very tame animals that could be observed from close quarters. The longest chapter is devoted to his colony of Jackdaws (Coloeus monedula), which he started by hand-rearing more than a dozen of them. He ringed his Jackdaws with colour and metallic rings and named them accordingly to their ring colours. This chapter is a vivid account of Jackdaw behaviour. Lorenz was of the opinion that you had to get under the animal's skin to understand their actions, and his fascinating account shows that he got very close to feeling like a Jackdaw and he was definitely treated by one with a male that adopted him as his partner and insisted in feeding him chewed worms.

Flying together
Jackdaws are very sociable corvids, they like to fly in tight flocks. The members flock feed together and breed together in loose colonies in natural holes in cliffs and old trees and in buildings commonly using chimney pots. He described the "kia" call as equivalent to "fly away with me" and a longer version he learned to distinguish "kiaw" as "fly back home with me". His first jackdaw, Jock found dark birds flying away from him irresistible, and would often pursue a Hooded Crow away in his walks with Lorenz. Adults use this instinct to entice young to fly with them and will keep a close eye "looking over their shoulders" as they do so, to make sure the young can follow. Lorenz noticed how adults adjusted their flight and made it slower when fledglings were flying with them, making it easier for the young to follow.

The rattling reaction
One of the most surprising discoveries made by Lorenz was the instinctive basis of the rattling reaction and how . He found by chance - by taking his black swimming trunks from his pocket - that a dark floppy object held by something was a very strong signal that started a furious attack. His tame jackdaw attacked his hand drawing blood. The pecking was accompanied by loud rattling calls. In other occasions - such as when he intended to ring the young jackdaws in his colony, he observed that holding the feathered young will draws the members of the flock together into a rattling reaction. This presumably has the function that a predator that catches a jackdaw receives such a severe punishment. The memory of the offender is imprinted into all the members of the flock participating in the rattling reaction and will persist for years and form the basis of local traditions that will be passed down generations. As the rattling reaction was elicited when Lorenz held feathered young for ringing, he decided to dress up with the only outfit he had at hand - a devil costume -  and climb onto his roof to ring the young jackdaws. A sight that shocked some of the people of his village one day.

A pecking order
The jackdaw flock has a precise stable hierarchy. There is a pecking order in which "very high caste jackdaws are most condescending to those of lowest degree and consider them merely as the dust between their feet" according to Lorenz. Males, which are larger than females are higher in the rank. High ranking jackdaws always takes the weaker side when intervening on disputes, which helps maintaining the cohesiveness of the colony. The way Jackdaws assert their dominance is by raising the neck pale feathers.

A pair of jackdaws basking in the early morning sun

Lifelong partners
Jackdaws are socially monogamous and pair for life. Pairs form on the individuals' first spring, although they are unlikely to breed until their second spring due to a shortage of nesting sites. The partners in a jackdaw pair are together all year round and support each other loyaly in any dispute. The rank of a new female partner automatically rises correspondingly in the female's rank order, a refinement of Lorenz discoveries explained in the later monograph on Jackdaws by A Roell. Lorenz said he was surprised how quickly all jackdaws in the colony knew of the rise in rank of the new partner of the recently arrived alpha male. But not only that, the female also knew that now she stood over everybody else! The male will show the female a nest site by calling her with "zink" calls. The bond between the pair is shown by allopreening, usually by the female which will preen her partner's neck, particularly his silvery feathers. The female also will beg for food and the male will courtship feed her as he will in time feed the young. Both male and female share the building and defence of the nest and the rearing of the young but only the female incubates. During incubation, the male will feed the female.

The few pairs of local Jackdaws now sitting on their nests remind me of Lorenz entertaining book.

More information
Konrad Lorenz (1954). King Solomon's ring: new light on animal ways Methuen, London Other: 0415267471

Röell, A. (1978). Social Behaviour of the Jackdaw, Corvus monedula, in Relation To Its Niche Behaviour, 64 (1), 1-122 DOI: 10.1163/156853978X00459

The hybrid goose in the park

I have known this goose since 2005. It is a hybrid between Canada Goose and possibly Greylag, and it turns up every winter in my local park. Today, it behaved gallantly, chasing away other geese and ducks while its partner, a Canada goose, fed.

The hybrid goose holds the pair of Canada away from the food source, allowing his partner to feed unmolested.

This goose is a large bird, with a mixture of features from both species (see photos of Greylag and Canada below), with the white patch on the face of the Canada, the pink legs of the Greylag and a beak half, black half pink.

A Canada goose

 A Greylag

 I think the hybrid is a male. He is paired with a female Canada and travels with a Canada flock. Hybridisation is a fascinating issue. In a puritanical view of species - which were created, would not change and could be nicely put into separate drawers - hybrids, were viewed as oddities: unnatural, often sterile, hard to put away in a neat drawer. This view has changed a lot lately. Recent genome sequencing data have shown that we humans seem to be a melange of different hominid isolates that mixed when they met; polar bears and brown bears have been shown to have often interbred during the Pleistocene; Carrion Crows and Hooded Crows do it; Willow Grouse and Rock Ptarmigan do it as well. There are many more examples. Natural climatic changes, such as during ice ages, often brings species together facilitating hybridization. Human introductions, placing species that previously didn't come together in the same areas can also promote hybridisation. Hybridisation is not only more frequent in nature than previously thought, but can also fuel species diversification and adaptation.
 Geese hybridisation is interesting as, when young, goslings undergo a phenomenon called imprinting. After hatching, goslings have a sensitive period during which they attach themselves socially to any moving stimulus, and follow it. This usually happen to be their parents, but they will eagerly follow people when goslings are hatced in an incubator. Even their mating preferences are determined to some point early in life, as goslings imprint on the adults that rear them - this is called sexual imprinting - and, when adults, will try and find a mate of the same species of the individuals that reared them. In nature, errors can happen. For example when individuals practice egg parasitism - laying eggs on another species' nest - or a brood from another species is adopted or brood amalgamation, when goslings from  different species pool together and the adults of one of the species take care of them.
 What happens to the fostered brood when they grow up? They imprint on their foster parents, which rear them as if they were their offspring, but they still look like their biological parents. Eric Fabricius carried out an experiment in the wild to examine the effects of sexual imprinting on hybridisation in geese. He swapped all eggs from two nests of Canada geese by Greylag eggs. The cross-fostered Greylags migrated with their Canada parents and upon returning to the breeding ground the following spring they paired up:

Of 35 returning birds, all 16 females paired with greylag goose males (100%) whereas of 19 males 5 paired with Canada goose females (14%) and the remaining 14 with greylag goose females (74%). The pair bonds generally persisted as long as both birds were present, but after loss of a partner, the remaining bird usually re-mated. Even when this happened several times during the lifetime of a male, the new mate was always a Canada goose female, showing that the males were sexually imprinted to this species. The Canada goose females which had mated with the greylag ganders also remated when widowed, but their new mate could be either a Canada goose or a greylag goose.

All cross-fostered females paired with Greylags. They looked like greylags, so they weren't courted by Canada males, just Greylag males. The pattern in the males is interesting, as they probably actively courted Canada females - and some accepted them-  but they were also found attractive by greylag females and they ended up pairing with them. Only the category of cross-fostered males pairing with Canada are likely to father hybrid offspring. What happens to the hybrid offspring is interesting as they do look intermediate between species. If is still unclear if hybrid CanadaxGreylags are fertile. The hybrid in the park then probably had a cross-fostered dad. He appears to have no trouble keeping a mate, and if he is always as considerate in his behaviour as today, she might as well keep him.

References
Fabricius, E. (2010). Interspecific Mate Choice Following Cross-fostering in a Mixed Colony of Greylag Geese (Anser anser) and Canada Geese (Branta canadensis). A Study on Development and Persistence of Species Preferences1 Ethology, 88 (4), 287-296 DOI: 10.1111/j.1439-0310.1991.tb00283.x


Edwards, C., Suchard, M., Lemey, P., Welch, J., Barnes, I., Fulton, T., Barnett, R., O'Connell, T., Coxon, P., Monaghan, N., Valdiosera, C., Lorenzen, E., Willerslev, E., Baryshnikov, G., Rambaut, A., Thomas, M., Bradley, D., & Shapiro, B. (2011). Ancient Hybridization and an Irish Origin for the Modern Polar Bear Matriline Current Biology, 21 (15), 1251-1258 DOI: 10.1016/j.cub.2011.05.058


Quintela, M., Thulin, C., & Höglund, J. (2010). Detecting hybridization between willow grouse (Lagopus lagopus) and rock ptarmigan (L. muta) in Central Sweden through Bayesian admixture analyses and mtDNA screening Conservation Genetics, 11 (2), 557-569 DOI: 10.1007/s10592-009-0040-9

Greylag Geese watching

 In the last couple of weeks, a small flock of a dozen greylag geese has started to come to the local Park. Greylags are one of the most interesting local birds to watch. Once they land, the orderly formation breaks and pairs separate and noisily settle scores before starting their feeding with ritualized neck posturing. Despite being in a flock, pairs are usually quite easy to spot, they follow each other and the gander is slightly larger than the goose. When showing aggressiveness, one of the pair members lowers its neck and shows the beak to its opponent, with the partner following close. On quiet times, where no people are feeding the ducks, greylags head up to the large grass spaces of the park to feed. These are no wild geese, if you show some interest in them, they are likely to come closer to check if you have scraps, or even come right to you to demand some depending on their personalities. To watch them doing what if comes naturally to them you need to feign indifference. Today I watch six of them grazing.

Konrad Lorenz, the Nobel prize, carried out long term behavioural studies on hand-reared greylag geese to allow close approximation. His geese - which were individually named - lived free but did not migrate, so he could study them year round. Lorenz describes geese behaviour in detail in his book 'Here I am - where are you?' Lorenz first discovered the phenomenon of imprinting on geese, by which newborn birds attach themselves to the first moving object they see after hatching. The description of his first, serendipitous, realisation of imprinting is quite moving: 

'After the first gosling had hatched and dried, I was unable to resist the temptation of removing the delightful creature from under the foster mother and taking a closer look. As I did so, it gazed at me and soon began to utter its single syllable lost calls [...] I answered with a few comforting sounds. [...] Eventually, however, I had enough of this babysitting and placed the gosling back under the wings of the brooding domestic goose and started to leave. I should have known better.' 

The gosling started making distress calls and when Lorenz starts moving away, it follows him. Lorenz did a lot of babysitting from then on! 

The Greylag goose triumph ceremony (from one of Lorenz's papers on the behaviour of the Greylag geese).