• Chelle Hartzer

Not Spiders (AKA: Down the rodent burrow)

I had every intention to write about spiders. It’s October which means it’s Halloween (my favorite holiday of the year!) and spiders are the best. Then I had to look up something on rats. That lead to thirty open tabs on my browser from numerous different journals and down the rabbit rat hole I went. I’m bringing you down with me: here are five things you never knew about rats.

1. It’s never just one. Okay, rarely it is just one if it was delivered in, but in most cases, if you got one in a trap, there’s plenty more where that came from. Norway rats live in family groups. They excavate large and complicated burrows that in some cases can have over 150 individuals in them. There are adults, juveniles, pups, and pregnant females all together in a burrow system that can have numerous entry and exit points. This makes estimating populations of Norway rats extremely difficult and as a result, controlling these rats is challenging. When trapping and/or baiting, it’s impossible to know how many rats haven’t been caught yet. If treating the burrows directly, it’s also tough to know that the treatment has gotten throughout the entire burrow or if rats have escaped out of their exit holes. It’s like trying to find that needle in the haystack, except you don’t know how many needles there are and you are blindfolded and can’t see the haystack.


2. Traps and bait don’t tell the whole story. We use monitoring devices to track populations and remove individuals from an area. To go back to the haystack example: if you find one needle, how many needles are still there? A study in Spain went into sewer systems in the city of Barcelona and found that the numbers they were seeing and recording, did not correlate well to the baiting and trapping data from the same sewer systems. In other words, there were way more rats in sewers than were being trapped or were eating bait. This does not mean traps and baits are not effective. It just means that using a wide variety of tools to manage rat issues.


3. Rats use tools. A recent study had researchers teaching rats to drive little plastic cars to get a food reward. This was a lab study, but they used two groups. The one group was the typical (pampered) lab rat while the other group was reared in more “natural” conditions. The second group did better and learned faster. This means our native rats could learn better and faster than lab rats. In another study, rats had to use a rake-like tool to get to a piece of food that was beyond their reach. Picture a rat using a stick or something to get to a piece of food behind a pallet or in a corner that’s just out of its reach. They are smart and will use tools.


4. Norway rats and roof rats can be found together. Not nesting with each other, but in areas very close to each other. It used to be that you had one or the other species, not both in close proximity. New field research is showing that as long as they have plenty of food resources, these two rat species are maintaining a truce with each other. Trapping research out of New Orleans, LA is showing shifting populations and finding roof rats and Norway rats in the same areas. Info from other large cities that have copious amounts of available food also shows populations of rats and house mice living in close quarters.


5. Rats are nicer than people. Scientists wanted to see if rats would help their friends in distress. They put a rat in a pool of water, forcing it to swim. The second rat, high and dry, could “rescue” the wet rat by opening a door, or it could open another door and eat a piece of chocolate. In more cases than not, the dry rat chose to help the soaked rat escape before going for the piece of chocolate. I’m not going to lie, if it was dark chocolate I might have second thoughts about rescuing someone... Aside from being a fun experiment, this shows that Norway rats are going to help their comrades instead of leaving them to fend for themselves. As a population, this makes Norway rats harder to control.



6. Rats are tough to capture. Even for professionals. Even when the rat is radio tagged! A single rat was let loose on a small island for researchers to see where it went and track its movements. All was going well. Until the rat decided to swim a quarter of a mile to another island. Oops. It managed to evade capture for 18 weeks despite an “aggressive combination of detection and trapping methods.” If anyone has ever dealt with that single rat in a building after all the rest of them have been eliminated, they know how tough that last sneaky scoundrel is to get.


Let’s recap: managing rats is like finding an unknown number of needles moving around in a haystack that you are blindfolded and can’t see while simultaneously knowing those needles are smart and working against you and helping other needles. This is why an integrated approach that focuses on prevention and keeping the rodents out in the first place is key. If you are dealing with rat issues, contact us here, we can help. If you are looking to review your rodent control program, contact us for an independent assessment*. Stay tuned for spiders next week.


*haystacks and needles specifically excluded!

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