Tuesday, May 24, 2011

Pale Male's Nest, Rats and gulp, Sanitation, Plus Pip Scuttles

Photograph courtesy of Cheryl Cavert

A Tulsa juvenile Red-tailed Hawk having successfully grabbed a rat, now must figure out how to dispatch and eat it.

A hawk this age doesn't know a poisoned rat from Shinola.

Which brings us to a question via the comments section I received from Riverside Park Hawk Watcher Melody Andres--

Interesting theory regarding the possibility of the build up of low doses of poison causing Lola to become infertile. It got me thinking. the Riverside Park single mom is looking better than ever since her mate passed away. The Eyasses born just 4 wks ago look more developed than last year's clutch at that age.

Is it possible that Mom and clan are benefiting from the rats being provided by the Parks Dept.? She is hunting but also accepts the food left for her so we know that at least part of her diet is untainted.

Certainly Riverside Mom and the eyasses are benefiting greatly from the supplemental rats. Everybody is getting all the food they need. It takes the pressure off her time and the energy that she would have to expend hunting alone for everyone. Plus as you say the supplemental rats are poison free were in good health and well fed. I don’t discount at all that most of the rats in NYC carry some poison in their bodies which is detrimental to the health and development of urban hawks.

Humans have been having an inter-species war with Brown Rats (No they didn’t come from Norway.) for centuries and as we have been attempting to exterminate them, evolutionary strategies have developed to win the war on their end.

Rats reproduce at an explosive rate. They become sexually mature at 5 weeks and can breed year round. Gestation is only 21 days and a litter can be up to 14. (And remember in just 5 weeks all of them can start reproducing themselves.)

Rats as a species become immune eventually to every poison we’ve come up with. Because of their high reproduction rate , rats with new combinations of genes are born constantly. Poison is set, many rats die, but those who didn’t die of the poison either by luck or are genetically superior and survive that poison produce young who are more likely to survive the poison as well. The rate of survival for that poison increases with each generation.

How many young do our urban Red-tail pairs produce per year? Zero to three. Because of their extremely low population in the first place at the top of the food chain and their low reproduction rate, Red-tails will never develop genetic immunity to rat poison. The rats on the other hand, eventually can eat poison bait like candy, have bodies full of it, and are not bothered in the least. All it takes is one bad rat per hawk and poof, empty territories.

Plus, and this is my “favorite” survival strategy of rats, when a large fraction of a rat community is exterminated the remaining rats increase their reproductive rate until the colony is quickly back to its previous population.

That is why poison will never ever do the job.

Yes, I said NEVER! And it is true.

The only thing that does work is to cut off the rat food supply. Rats are hierarchical. When the food supply is low , the lower classed rats die first and then on up the social ladder. If they can’t eat, they can’t reproduce.

No species becomes immune to no food.

The whole thing is a no brainer.

Sanitation, sanitation, SANITATION!

Photo courtesy of palemale.com

After sharing a pigeon for dinner, Pale Male and Ginger Lima admire their eyasses, one on each side of the nest bowl. I'm always relieved when they eat something besides rat for a meal.

Tonight Pip isn't sleeping under Violet's wing, but rather up against the front curve of the nest.

Evidently he got chilly, having no nest mates to sleep in a pile with, so he scuttled over to mom for a warm snuggle.

Donegal Browne

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