Crow thoughts
Jun. 27th, 2022 09:03 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
greenstormAlright. So it's my job as a land steward to create a system that fits into the larger ecosystem. Sometimes that's fun and easy. Sometimes it's challenging. With the crows, obviously, it's challenging.
Here's a first brainstorming run:
Like with coyotes, crows are smart and it makes sense to cultivate a resident population that has behaviours that help me and that don't harm. My friend T had a raven issue (apparently where they are ravens are territorial, here I get a ton of them) and they killed the problem ravens, then had a pair of ravens move in that didn't do those behavioural issues. Having crows here does keep ravens away, which helps for not having farrowing pigs eaten but causes obvious crop problems.
So categorically, options seem to be trying to keep all ravens away through killing them or scaring them (this seems unlikely to work long-term since if I kill them more will move in, and scare-based stuff tends to loose effectiveness over time unless I get a bird-chasing dog or something); training them not to go after my corn; or making my corn inaccessible somehow. A fourth option, giving them something else nicer to eat, isn't a real option because of how population dynamics works: they'll just keep multiplying until they can eat both my garden and my offered decoy food.
I suspect what works will be a combination of these things. I definitely prefer less infrastructure and inputs, and will be working towards breeding corns that the crows tend not to bother (taste? strong roots before a shoot comes up so they can't be pulled? who knows what the plants will figure out) but I need enough seed for heavy selection to make this work.
Right now cost is a bigger issue for me than amount of input, I think. I also like to reduce plastic use, especially short-lifespan plastics.
Killing/Scaring
Killing the current set *might* cause a different set to move in that doesn't have the learning that pulling up corn is fun.
Keeping the pig and bird food extremely tightly controlled so they can't eat any of it ever might help keep the population low and the level of interest in my garden commensurately low. This would involve a bunch of infrastructure: each field would need an enclosed pig feeding structure (or maybe only in winter and early spring, since that's when I'd expect the most starvation to occur). Birds are easier to make an enclosed feed structure for but harder to exclude crows from that structure since they are also birds. There is almost always some kind of food the birds get at when I do grocery pickup at the store, grocery pickup might be a casualty of this or I'd need additional indoor shed space to store the food plus the garbage it makes.
Scaring crows involves movement, noise, and things that look like predators. A dog that chases crows would be great, though keeping it out of the garden would be important and I have trouble imagining how to keep it hostile towards them instead of acclimatizing over time. It's possible that a radio and some gunshot noises or something that sounds like people and bangs, if deployed only during the seeding window, would help keep them away for a season or two before they figured it out. It might be a helpful layer of control but certainly not dependable.
Almost everyone recommends killing one and hanging it up to scare them, or getting "halloween crows" to hang up, whatever those are.
Training
Maybe it makes more sense to call this "convincing" the crows.
If there's something that makes the corn taste bad maybe the birds would stay away from it. Since I do a pre-soak anyhow it wouldn't be difficult to soak it in something. I see there is a commercial repellant called "avipel" that I would need to look into.
The crows aren't eating the kernels at this point, but it's possible that if I low-level poisoned some and set them out (think stomachache, not death) then the crows would leave the corn alone in future, or maybe if I set some out each year before seeding. That has some drawbacks: dose so as not to kill anything is important, I'm neither looking to kill them nor to get bad stuff into the food chain, I'm not sure what would produce that effect, if the poisoning agent had a scent maybe the crows would just not eat whatever smelled like that.
I have limited water pressure and power up there, but there are motion-activated squirting devices that are supposed to also deter deer etc. I'm not sure how well they work, or whether the crows could outsmart them, and they're not cheap, but I've been considering them for a couple years now.
Maybe running an electric fence wire right over the row of corn might shock them if they couldn't avoid touching it when they pulled the corn up? Not sure how well grounded crows are and this would take infrastructure.
Removing Access
Floating row cover is working best for me this year, but it's a consumable plastic item (lasts a couple years) that also costs money. It does make the corn grow faster and protect from frost. They do seem to try pulling the corn up when it comes off but there must be a size where they give up on that. I have 5' wide strips right now, square blankets that would cover most of my garden at once would make it easier to keep bird out from the edges. This costs money.
Piles of twiggy branches may help keep the crows from getting at the beds, or if they can make their way into the twigs (they do move through trees no problem, after all) it can keep them from flying away quickly so maybe they will feel unsafe/I'll be able to get one with a pellet rifle and then they'll feel unsafe.
Netting over the field would also help with harvest time, since I suspect I'll have an even bigger battle there even if I bag each corn ear. This would involve a lot of posts for infrastructure, and I think there are some downsides for small birds (they can get caught in the mesh?). Posts are something like $15-20 apiece right now, this isn't a cheap option.
Polytunnels, either high or low tunnels, with either mesh or actual poly on them: these are expensive, they'd mess with my breeding a little bit (if I used poly they'd be warmer so I'd get better crops), they'd need irrigation inside. On the other hand they'd do the job, they could function as barriers to cross-pollination so I could control that better, high tunnels might be good overwinter spaces, I could grow way more stuff, they're generally great. These would also need irrigation if they have poly on them.
Hilling, which I did this year, involves pulling soil up against the stem once the corn is a couple inches tall. If only the leaves are sticking out, the birds can't grab the base of the stem to strategically pull out the roots and the plant is less likely to be injured, plus they just don't seem to go after them as much once hilled. This is cheap, a little labour intensive, and only works once the corn is a couple inches tall so it needs to be got to that point to start (maybe through row cover or a bad smell/taste).
Deep planting is what I tried doing this year, putting the seed in deep and tromping the soil down around it fairly firmly so it's not easy to grab the seedling and pull up the root but instead the top just breaks off. The crows wait until rain/watering when the soil is soft to pull, but it seems to still help and allows for some regrowth at least.
Mulch isn't precisely a barrier, but I tried putting fresh green mulch down in the hopes the crows would have trouble seeing the new sprouts to pull. Because they slowly walk across the field from one end to the other this didn't help much; they're not just flying over and spotting things that way. Also I know the infrared on dying plants (like ones cut for mulch) is much different than on healthy ones and I'm not sure how crows' vision is.
It's possible a deep straw mulch would be helpful at obscuring the seedlings until they were too big to pull. It would soften the ground, making it easier to pull. On the other hand it would add organic matter and retain moisture so it would be good for the plants, and big bales of straw are relatively cheap, though they're labour-intensive and need to be bought the fall before.
Someone mentioned that they plant into their weeds, making a little 8" wide opening and putting in several kernels of seed, then only weeding the rest of the weeds when the corn is a foot high or so.
I've noticed that two plants growing close together are less likely to be pulled up than plants evenly spaced. Maybe put 2-3 kernels together per foot, instead of spacing 4-6" in the row?
The crows didn't really touch my Saskatoon White. I wonder if that was a fluke or if it means I should just grow more Saskatoon White?
Here's a first brainstorming run:
Like with coyotes, crows are smart and it makes sense to cultivate a resident population that has behaviours that help me and that don't harm. My friend T had a raven issue (apparently where they are ravens are territorial, here I get a ton of them) and they killed the problem ravens, then had a pair of ravens move in that didn't do those behavioural issues. Having crows here does keep ravens away, which helps for not having farrowing pigs eaten but causes obvious crop problems.
So categorically, options seem to be trying to keep all ravens away through killing them or scaring them (this seems unlikely to work long-term since if I kill them more will move in, and scare-based stuff tends to loose effectiveness over time unless I get a bird-chasing dog or something); training them not to go after my corn; or making my corn inaccessible somehow. A fourth option, giving them something else nicer to eat, isn't a real option because of how population dynamics works: they'll just keep multiplying until they can eat both my garden and my offered decoy food.
I suspect what works will be a combination of these things. I definitely prefer less infrastructure and inputs, and will be working towards breeding corns that the crows tend not to bother (taste? strong roots before a shoot comes up so they can't be pulled? who knows what the plants will figure out) but I need enough seed for heavy selection to make this work.
Right now cost is a bigger issue for me than amount of input, I think. I also like to reduce plastic use, especially short-lifespan plastics.
Killing/Scaring
Killing the current set *might* cause a different set to move in that doesn't have the learning that pulling up corn is fun.
Keeping the pig and bird food extremely tightly controlled so they can't eat any of it ever might help keep the population low and the level of interest in my garden commensurately low. This would involve a bunch of infrastructure: each field would need an enclosed pig feeding structure (or maybe only in winter and early spring, since that's when I'd expect the most starvation to occur). Birds are easier to make an enclosed feed structure for but harder to exclude crows from that structure since they are also birds. There is almost always some kind of food the birds get at when I do grocery pickup at the store, grocery pickup might be a casualty of this or I'd need additional indoor shed space to store the food plus the garbage it makes.
Scaring crows involves movement, noise, and things that look like predators. A dog that chases crows would be great, though keeping it out of the garden would be important and I have trouble imagining how to keep it hostile towards them instead of acclimatizing over time. It's possible that a radio and some gunshot noises or something that sounds like people and bangs, if deployed only during the seeding window, would help keep them away for a season or two before they figured it out. It might be a helpful layer of control but certainly not dependable.
Almost everyone recommends killing one and hanging it up to scare them, or getting "halloween crows" to hang up, whatever those are.
Training
Maybe it makes more sense to call this "convincing" the crows.
If there's something that makes the corn taste bad maybe the birds would stay away from it. Since I do a pre-soak anyhow it wouldn't be difficult to soak it in something. I see there is a commercial repellant called "avipel" that I would need to look into.
The crows aren't eating the kernels at this point, but it's possible that if I low-level poisoned some and set them out (think stomachache, not death) then the crows would leave the corn alone in future, or maybe if I set some out each year before seeding. That has some drawbacks: dose so as not to kill anything is important, I'm neither looking to kill them nor to get bad stuff into the food chain, I'm not sure what would produce that effect, if the poisoning agent had a scent maybe the crows would just not eat whatever smelled like that.
I have limited water pressure and power up there, but there are motion-activated squirting devices that are supposed to also deter deer etc. I'm not sure how well they work, or whether the crows could outsmart them, and they're not cheap, but I've been considering them for a couple years now.
Maybe running an electric fence wire right over the row of corn might shock them if they couldn't avoid touching it when they pulled the corn up? Not sure how well grounded crows are and this would take infrastructure.
Removing Access
Floating row cover is working best for me this year, but it's a consumable plastic item (lasts a couple years) that also costs money. It does make the corn grow faster and protect from frost. They do seem to try pulling the corn up when it comes off but there must be a size where they give up on that. I have 5' wide strips right now, square blankets that would cover most of my garden at once would make it easier to keep bird out from the edges. This costs money.
Piles of twiggy branches may help keep the crows from getting at the beds, or if they can make their way into the twigs (they do move through trees no problem, after all) it can keep them from flying away quickly so maybe they will feel unsafe/I'll be able to get one with a pellet rifle and then they'll feel unsafe.
Netting over the field would also help with harvest time, since I suspect I'll have an even bigger battle there even if I bag each corn ear. This would involve a lot of posts for infrastructure, and I think there are some downsides for small birds (they can get caught in the mesh?). Posts are something like $15-20 apiece right now, this isn't a cheap option.
Polytunnels, either high or low tunnels, with either mesh or actual poly on them: these are expensive, they'd mess with my breeding a little bit (if I used poly they'd be warmer so I'd get better crops), they'd need irrigation inside. On the other hand they'd do the job, they could function as barriers to cross-pollination so I could control that better, high tunnels might be good overwinter spaces, I could grow way more stuff, they're generally great. These would also need irrigation if they have poly on them.
Hilling, which I did this year, involves pulling soil up against the stem once the corn is a couple inches tall. If only the leaves are sticking out, the birds can't grab the base of the stem to strategically pull out the roots and the plant is less likely to be injured, plus they just don't seem to go after them as much once hilled. This is cheap, a little labour intensive, and only works once the corn is a couple inches tall so it needs to be got to that point to start (maybe through row cover or a bad smell/taste).
Deep planting is what I tried doing this year, putting the seed in deep and tromping the soil down around it fairly firmly so it's not easy to grab the seedling and pull up the root but instead the top just breaks off. The crows wait until rain/watering when the soil is soft to pull, but it seems to still help and allows for some regrowth at least.
Mulch isn't precisely a barrier, but I tried putting fresh green mulch down in the hopes the crows would have trouble seeing the new sprouts to pull. Because they slowly walk across the field from one end to the other this didn't help much; they're not just flying over and spotting things that way. Also I know the infrared on dying plants (like ones cut for mulch) is much different than on healthy ones and I'm not sure how crows' vision is.
It's possible a deep straw mulch would be helpful at obscuring the seedlings until they were too big to pull. It would soften the ground, making it easier to pull. On the other hand it would add organic matter and retain moisture so it would be good for the plants, and big bales of straw are relatively cheap, though they're labour-intensive and need to be bought the fall before.
Someone mentioned that they plant into their weeds, making a little 8" wide opening and putting in several kernels of seed, then only weeding the rest of the weeds when the corn is a foot high or so.
I've noticed that two plants growing close together are less likely to be pulled up than plants evenly spaced. Maybe put 2-3 kernels together per foot, instead of spacing 4-6" in the row?
The crows didn't really touch my Saskatoon White. I wonder if that was a fluke or if it means I should just grow more Saskatoon White?
no subject
Date: 2022-06-28 08:48 pm (UTC)are you using plastic row cover, or frost cloth? we've gotten frost-cloth to last 5-6 seasons with care before.
halloween crows are feathered stuffed toys folks use for decoration - some are pretty realistic and might work as decoys. also maybe decoy owls? do owls eat crows? those are used in pigeon management here.
no subject
Date: 2022-06-28 10:45 pm (UTC)Right now the birds eat from dishes that are inside structures, but the doors on the structures are open (and the geese hate going inside, which I sympathize with)
I'm using what I know of as floating row cover. It's a spun, semi-opaque lightweight material that can sit right on top of the plants without harming them, lifts while they grow, and lets water and light through. It's easy to put holes through accidentally, which is fine if I just handle it gently, but the bigger the piece gets the easier it is to rip off the edge just trying to lift it. I know there's a thicker and thinner kind, mine is a little bit thicker than many. 6 seasons would make me pretty happy! I expect I can get 3-4, this is the second season and some of it is ok and some will need to be discarded from the learning process (if you fold it together and it freezes, for instance, it will tear when you try unfolding it. Or if there's a big rock on it. Or...)
Huh, I guess I don't usually participate in Halloween except to restock my year's worth of reasonably-sized candies, I am not sure I've seen those. I know they sell solar-powered moving decoy owls, I think with the dead crows they don't need to move to be scary. Heh. Whereas anything stationary gets observed and if it doesn't move for long enough it becomes just background.
The crows definitely have a watching network all through the neighbourhood, and will call up and down the street if there's food or a threat. It was maddening to have them make the food-call from my cornfield at first light at 4am, it really did disrupt my ability to go back to sleep and they just scattered if I went up there and then regrouped when I came back to the house. Ugh. But I suspect they'd communicate abotu fake owls. There are also all kinds of weird eye things (balls, hanging shiny things) that are like very abstract pieces of owl designed to scare them away.
no subject
Date: 2022-06-28 11:00 pm (UTC)i have heard that taking whole or partial CDs and stringing them up so they flash in the sun can help deter birds; idk if it's true. that might have also been against pigeons.
we cut the holes into the trash can with a sawzall. handy thing, that. we have a cheap battery-powered one we got a yardsale that has held up remarkably well. then stuffed the elbows in, and caulked around the seam to hold it in, since pushing them through stretched it a bit. i'll have to take a closer look at it but i'd estimate the holes are at 8", 11", 14" off the ground.
no subject
Date: 2022-06-28 11:30 pm (UTC)Looking at the different thicknesses of floating row cover/frost cloth, some looks very transparent - pretty sure crows would learn to rip through that. I'll need to stay with the thicker stuff I can't see seedlings through directly.
Caulk! That makes sense. The elbows have a slight flare on their edges, I was wondering how they'd hold in. Caulk makes sense. Thank you.
no subject
Date: 2022-06-29 04:02 pm (UTC)no subject
Date: 2022-06-29 04:16 pm (UTC)no subject
Date: 2022-06-29 04:19 pm (UTC)no subject
Date: 2022-06-30 02:47 am (UTC)With electrified wire, it would be difficult to keep it from sagging too low without lots of additional posts. And if it *did* sag too low, or the corn grew too fast, the corn would get fried. It's probably already too much infrastructure with one line, but maybe if you had *two* wires, one on each side of the row, so the corn poked up through it?
If you already have an electric fence, you could pretty easily do an experiment where you put some crow-attracting food under a line and see if the crows are grounded enough to get zapped by it. Or just watch how they deal with it.
On the learning/aversives front... we had a problem at one point with deer jumping over the electric fence, and my dad used a nasty trick he'd heard about: Wrapping a twist of aluminum foil on the wire at intervals, with a dab of peanut butter on it. Deer is attracted by the peanut butter, takes a lick, gets the bejeezus zapped out of it, and usually smashes the wire in the process but then avoids the fence entirely after that point. Similarly, you could put out a real electric wire along a row and wrap it in tinsel (?), let the crows learn about that, and then just stretch some tinsel between posts for additional rows as fake wires and maybe they'd avoid those too.
I wonder what size netting you would need. I feel like it would be big enough that small birds wouldn't get tangled easily.
no subject
Date: 2022-06-30 04:13 pm (UTC)And yeah, using most of these only for a little while a year seems important. No sense wasting however long I have before they learn.
I don't see the plants that grow up along my electric fence nowadays being harmed. I have a bunch of little solar-powered energizers that I use for the pigs, so I could certainly experiment.
Yeah, for bears here you fill tuna cans with wet cat or dog food and hang them on the electric. Otherwise the bears just plough through the fence without stopping long enough to notice.
Oooh, I like the fake electric fence idea. Hm. I wonder if they'd be like the pigs, and test it once in awhile just to be sure, and then learn which rows were ok?
Small birds seem to get tangled in everything when they're flying. :(
Floating row cover will definitely be the easiest...
no subject
Date: 2022-07-01 12:51 am (UTC)As for the actual sprinklers, he says Contech is good, but expensive (or at least the model he got some years back was); Hoont is also good, and is less expensive; Hav-a-heart is no good.
I'm really surprised your plants don't get fried! Any plants that touch the garden's electric fence for long die back by a few inches. (Parmak Solar Pak 6, both the energizer and the fence are well-grounded. The fence encloses 3000 sq ft and has 4 grounding rods, in case you're curious.) Not sure why it doesn't kill the whole stem, come to think of it... maybe the spark finds the larger xylem channels eventually.
How many row-feet of corn are you needing to protect, anyhow? I realized I don't actually have a sense of that.