March 29, 2016
Attack of the ravens
It's always something with chickens. Both chickens and eggs are easy prey to a variety of predators and scavengers. In the past few years we've had dogs and skunks eating the chickens and squirrels stealing eggs. This spring ravens (and perhaps crows as well) decided to get in on the game and go after our eggs. And once one raven finds a reliable source of food, you can bet that others will follow. Indeed, a few days after we spotted the first raven they started coming two or three at a time.
Not quite the haul we were expecting.
The first sign of trouble was a steep drop in the number of eggs collected and finding the wool that lined the nest boxes strewn about the ground. At first we thought it was squirrels, but seeing a raven with an egg in its mouth revealed that we faced a bigger problem.
Initial attempts to fight back
Our chicken coop.
Once we knew the source of the problem, we could get to work solving it. Our first attempt was to seal any openings in the coop with chicken wire and leave the door to the yard closed. That worked for a day, but the roof of our coop is a plastic sheet, and the ravens soon started punching holes in it.
When the ravens want in, they find a way.
We could have protected the roof as well, but that would be a lot of work and wouldn't be a long term solution, since we didn't want to lock the chickens out of the yard long term. ravens being much cleverer than chickens, it's hard to imagine a way to give the chickens access to the yard without giving the ravens access to the coop.
The door to the yard
Several other attempts were made to keep the ravens out or drive them away, none successful.
A solution is found
It became clear that we couldn't keep the ravens away from the nests. But maybe we could hide the eggs. I tried roll-out nest boxes. Not knowing if this would work (and thus preferring not to dismantle our current nest boxes), I built an add-on that could fit onto our existing nest boxes.
The old nest boxes
The nest boxes with the roll-out add-on.
They were a big success! With the raven predations, we were lucky to get a handful of eggs a day. The day after installing the add-on, I was greeted by the following delightful sight:
In the two weeks prior to installing the add-on, we'd collected an average of 5 eggs per day, and that was with checking every hour or two in an attempt to beat the ravens to an egg or two. In the two weeks after installation, we averaged 16 eggs per day.
Roll-out nest box add-on design
The base and walls, with the lid sitting behind them.
Most of the dimensions of the add-on were determined by the dimensions of our nest boxes. The variables were the angle of the base and the height and depth of the egg compartment. Looking online 8° was a typical slope, so I used that. The height of the egg compartment is 2.5'', or about 0.75'' higher than the width of our largest eggs. I made the depth 10'', which I figured would be deep enough to prevent a raven from reaching the eggs.
I wasn't sure if our chickens would like to lay on bare wood, so in one nest box I used a 0.5'' thick rubber mat, and in another a rubber mat with some straw on top. The third was bare wood with a light scattering of straw. I used wool from our sheep to cushion the bottom of the egg compartment. The egg compartment was locked with a simple latch.
Feedback from the hens
The hens took to the new nest boxes well enough. They did start laying about half their eggs in random places, which luckily the ravens don't seem to have found. I'm not sure whether that's out of dislike of the new boxes, or due to lack of room (three boxes aren't enough for 28 hens).
There is some room for improvement. First, the straw quickly slid into the egg compartment. Second, I noticed that the hens were scrabbling to keep their footing on both the wood and the rubber. Third, about 1 in 30 eggs found in the roll-out nest boxes were broken. Finally, dirt (and occasionally poop) started to accumulate in the egg compartment.
I built the second set of roll-out nest boxes with modifications based on what I observed from the first one. Since the rubber base didn't seem to help, I left the wooden base bare for now. Tests with our eggs showed that they would roll on a 5° slope (even if the base was dirty). To make them easier to clean, instead of screwing on the bottom wall of the egg compartment, I attached it to the side walls with two 1/4'' bolts. To clean the nest boxes, I slide the bolts out, remove the bottom wall, and sweep out the dirt.
The removable bottom wall
The second set was painted to slow the wood's deterioration. The first set was modified according to the new design and painted. The 5° slope works fine for the eggs, but the chickens still didn't seem comfortable, and even with 6 boxes available were still laying some of their eggs on the ground. I'll try some nest pads to see if those will help.
In addition to being a solution for our raven problem, the roll-out nest boxes will come in handy in case the egg-stealing squirrels return or a hen decides that eggs look tasty. While chickens can be a hassle, they provide excellent exercise for one's ingenuity and patience.
May 1st: I added some upside-down linoleum sheets to the nest boxes. The chickens seem much more comfortable and are laying most of their eggs in the boxes now. The eggs still roll into the enclosed area.
A cut linoleum sheet ready to go into a nest box. The small indentations help the chickens get a grip.
July 1st: egg-stealing squirrels have returned, but unfortunately the roll-out nest boxes don't help. The squirrels seem to be climbing into the enclosed area and taking the eggs.