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Thursday 13 October 2011

Random Garden (Chicken, Household) Update (2)

Lucretia is latest member of our chicken flock (hospice) to die. RIP Lucretia (Lucy). Lucretia was a Shaver Brown with plumage colour in reverse of our other shavers. She was an older hen whose eggs had characteristic rough, thin shells. She was (ultimately) killed by egg peritonitis, a nasty condition where the yolk of the egg is dislodged from the oviduct into the abdominal cavity causing a massive infection. Shavers are bred to be a super-layers who (so we are told by the vet) often suffer egg-laying related fatalities when they are older, instead of successfully undergoing chicken-menopause and dying of other age related complications.


At the end Lucretia was comfortable, warm, calm, and hydrated at the vet clinic; after determining there was nothing he could do for her, the vet gassed her to death behind closed doors in what we can only assume (and hope) was a humane way. We buried her under a tamarillo bush.

Interestingly, if you look at the background of the above photo you may notice  Plantago (plantain - but I'll call it Plantago to avoid common-name confusion with Musa species) under Lucretia's feet. I'm about 98% sure its Plantago lancelota - I haven't formally keyed it out.

Our chickens have destroyed all forms of greenery within their domain except the Plantago which they will not touch (we supplement them daily with plenty of additional greens from the gardens and property).

As a result Plantago is spreading rapidly throughout their enclosure - the chickens are structuring the plant-community composition within the pen. In terms of food-web theory this would be considered top-down control on plant-community composition by the chickens.

The chickens are inadvertently selecting for the Plantago (more precisely the mechanism and ultimately alleles responsible for its unpalatability). Should a mutant Plantago arise that lacks this chemical and/or structural defense against chicken-browse (and should the chickens decide to sample it) it will be toast. Whatever alleles are responsible for the characters making Plantago inedible are probaly undergoing stabilising selection. At one end alleles resulting in a reduction of unpalatability would be purified by the chickens - those plants (allele sacks) wouldn't live long enough to pass on said alleles to the next generation. At the other end alleles resulting in more extreme (but unnecessary) amounts of defence might involve a resource-allocation based trade-off that would leave those plants at a disadvantage with their con-specifics.

If  some other plant species equally unpalatable to chickens disperses into the pen its frequency may also continue to increase - but that would be determined by its ability to effectively compete with the established Plantago for resources (light, nutrients, space).

Over a much, much longer time period (assuming the chickens continued their brand of top-down control)  other cool interactions could occur: Forms of unrelated plants resembling Plantago might arise (mimicry). Chickens with a taste for/ability to utilise Plantago might also arise (if we added a rooster or two), giving them an advantage over chickens with more restricted diets.


Random Garden Update (1)

Lately I have been abandoning posts about two paragraphs in, because:

1) I get bored and think, why be bothered, a generally interested person could get all they need on this topic via Wikipedia.

2) I realise the idea is too complicated to communicate in a blog format and what I'm actually doing is using the blog to consolidate my own thinking on the issue - which is fine for me, but for a hypothetical reader the results are... not particularly... coherent.

So in an attempt to get back in to the swing of blogging practice i offer/subject you, the reader, to the blogging equivalent of a rant about last nights dream or a tour through a family photograph album.

We have been receiving springtime visits to our home garden from Kererū (Hemiphaga novaeseelandiae), a wood pigeon indigenous to New Zealand. The other evening there were five of these birds up in the plum trees.


Unfortunately, the Kererū are not visiting in order to service our viewing pleasure, they are after food - specifically plum blossoms. This is troubling as for every blossom they feast upon, we lose a potential plum and five beautiful Kererū can demolish a lot of plum blossoms in a week-long course of both morning and evening visits.