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Posts Tagged ‘habitat’

The lone mason bee I saw last week.

Last year I started raising orchard mason bees (Osmia lignaria), which are cute little solitary bees that live in holes in masonry or wood, or in the case of my bees, in paper straws made specially for them. At least, in theory mine live in straws.

Keeping mason bees is a much simpler affair than keeping honey bees. Mostly it’s just providing nesting space (straws or reeds), mud (they use it as dividers between eggs), and pollen during their active period, which is in the spring. After they’ve laid all their eggs or their wings are too tattered to fly, which is around when most fruit trees stop flowering, the adults die, and you put the straws which are now full of  eggs and larva somewhere warm and protected from birds, beetles, and mice. Then in the fall, you pop the straws in a refrigerator until a few weeks before the fruit trees begin to bloom in the spring. In the fall, you’d generally also want to open up some of the straws and check for pests, which only takes a few minutes.

Since last year was my first year raising mason bees, I slightly screwed up this process, and when I put the straws inside in mid-summer, I put them in the basement, but I should have put them somewhere warmer. This Spring, I put some of the tubes out in March, and some in April. Until today, I though I may have killed them all, because I had only seen a single bee hanging out around the bee house, and I should have at least 60 cocoons. Usually in the spring, the males emerge first, and hang around the nesting holes until the females emerge, so they can mate with them. Then the females go out and gather pollen and mud, lay eggs on top of piles of pollen, and seal off the eggs with a wall of mud, and then repeat the process until they die a month or two later.

Because I thought I had killed off all my orchard mason bees, and it’s too late to order more this year, I decided to try summer mason bees, Osmia californica. Californica bees are very similar to orchard mason bees, except they emerge later in the year, they use chewed up leaves instead of mud to separate their eggs, and they prefer aster-type flowers. I got my little carton of 20 californica bee cocoons in the mail today from Crown Bees, and I was surprised when I opened it that it smelled distinctly like flowers.

Osmia californica, with my index fingertip for scale.

There was also one little bee that had emerged from his cocoon during shipping that was crawling around in the box, so I carefully slotted the carton into the mason bee house I made last year, and got to watch him crawl out to the roof of the house to sun himself. I started taking photos of him crawling around covered in the pollen that had rubbed off on him as he made his way through the other cocoons, and it didn’t take long to notice that there were some orchard mason bees also flying around near me. I couldn’t figure out why they seemed to be bouncing off the wall next to the bee house, instead of flying into it, so I stood back a few feet in case I was in the way. This is when I realized that they weren’t accidentally missing the bee house- they’re heading for old nail holes in the wall instead. It makes me wonder if the others are either just late to emerge, or are perhaps nesting in my wooden shingles. I’m not sure why they’re shunning my paper tubes, but I’m glad to know they’re not all dead.

This little orchard mason bee is hanging out in old nail holes instead of in the paper straws in the mason bee house. This one looks like like a male to me, so he’s just hanging out, but if I’m wrong and it’s a female, it may be depositing pollen and laying eggs in that hole.

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The bees are free

I had been waiting to take my tubes of mason bees out of the cheese drawer in the fridge and put them into the garden until I had enough pollen to feed them, and that day has arrived. One of my viburnums has been providing me with clusters of white flowers all winter, but one shrub isn’t enough of a feast for the approximately 40 mason bees my garden will be hosting. Also, since this is my first year keeping mason bees, I’m not even sure if they’ll like the viburnum flowers. This weekend I noticed that the creeping myrtle (Vinca minor) and blue bells (Hyacinthoides non-scripta) have bloomed, and if the bees are willing to venture across the street, there are plum trees and forsythias in full bloom.

I opted to make my own bee house, and because I’m still a beginning wordworker, I made a 3-D model of it first in Sketchup, Google’s 3-D drawing program. Sketchup is a fun program for planning out woodworking projects, once you get past the learning curve of how different it feels than most 2-D drawing software, or even other CAD software. I’m having doubts that it’s a good overall garden planning tool, but I’ll save that discussion for another post. If you’re interested in making a similar bee house (or it could also easily be converted to a bird house), it would be possible to make a very similar one with only a miter saw, or maybe even a circular saw, but I wanted fancy miters on the corners, which would have been tricky without a table saw. The french cleat I used to mount it also could be tricky without a table saw.

I filled the house with mostly EasyTear straws that I got from Crown Bees, because they’re cheap, clean, and hopefully won’t be a hassle when it’s time to open some straws and check on the bees in the fall. I also added a few bamboo sections, mostly out of curiosity whether the bees would use them. The sticks you can see jutting out here and there I added to give visual cues to the bees to help them figure out which straw is theirs. I added the blocks of wood on top so that a bird or other animal wouldn’t find it convenient to nest right on top of a tasty food source. The house is mounted against a wall that gets great morning sun, and right above the garden with my peas and raspberries.

The final ingredient the bees will need is mud, but that certainly won’t be a problem to find in the coming weeks in Seattle!

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The other day I was browsing Etsy for garden art, and came across some beautiful whimsical bird feeders, and was about to buy them when I thought, “Wait- should I even be feeding the birds?”

What are scientists saying about bird feeders? It definitely can make a difference in both the survival and behavior of birds, but calling those changes good or bad is tricky.

A few of the effect of feeding birds that researchers have figured out:

  • Feeding birds during the winter and spring can cause birds to lay their eggs earlier, lay larger eggs, or have larger clutches. Both laying earlier and larger eggs tends to increase hatching and survival rates. Like all the other results I’ll mention, some bird species seem more susceptible to these changes than others. The magnitude of these effects also depended on the quality of the food provided to the birds- in a study of Florida Scrub Jays, birds fed high-fat high-protein diets layed first, birds fed high-fat low-protein diets layed next, and the control group that had only food that they foraged layed last. Extra food makes the most difference in tough environments such as cold winters and poor-quality habitat.
  • Adult birds sometimes feed their chicks the human-provided food, or sometimes eat the provided food themselves, which allows them to give more of the food they forage to their chicks. Unsurprisingly, when the chicks themselves receive the human-provided food, high-quality food has a positive effect on the growth of chicks, but low-quality human-provided food can have a negative impact on the growth of chicks. This is one of the clearer lessons in whether feeding birds is a good idea- for those who are tempted to toss bread crumbs or other human food out for the birds without considering whether it is nutritious to birds, consider that you may be doing them more harm than good.
  • Fast growth in chicks is considered good, but once birds are adults, many bird species regulate their weight to balance their perceived risk of starvation with the ability to get away from predators quickly. At first glance it may seem like if feeders aren’t constantly full, we’re messing up the birds’ body-weight calculations, or if they are always full birds might become dependent on them, but we should remember that most birds expect to get food from several different places. Even when easy food is available in a feeder, most birds will also keep track of several other patches of food, expecting some of them to disappear now and then. This lack of dependency was confirmed for black-capped chickadees in a study during a Wisconsin winter, where feeders were suddenly withdrawn, and chickadees that had previously used the feeders did just as well as ones who hadn’t. The authors point out that since the study was done in a rural area, where natural food may be more available than urban areas, the results might not hold true for cities. Since Seattle gets very little snow in the winter, I’m guessing that even the city gardens in my neighborhood have plenty of natural food for little birds like chickadees to get by.
  • Some folks are concerned that bird feeders increase the number of little birds getting eaten by predators. It turns out that how many birds are caught by predators depends on how and where your feeders are set up. Overall, though, researchers actually think that little birds get eaten at feeders less often than they would in the wild. The biggest predators at feeders are hawks and cats, though if you have eagles or snakes in your yard, they might be your biggest suspects. The feeding setups with the highest levels of hawk predation are near deciduous woods, have large feeding areas, year-round feeding, and lots of feeders. Cats got the most birds when bird feed was on the ground. If you want to prevent your cat from eating birds, put a bell on your cat, and keep bird food off the ground. Especially since bird feed on the ground is also rat food.
  • Researchers know that some diseases and harmful microbes spread through feeders, including mycoplasmal conjunctivitis and salmonella. To prevent this, take your feeder down and give it a good washing with hot water and soap, making sure to thoroughly rinse out the soap. For the same reason, wash your hands after handling bird feeders.
  • The ranges of several birds has expanded in the last 50 years, as bird feeding has become more popular, and some bird populations are overwintering in places they used to migrate away from. There are a few things that could explain these behavior changes, but feeding of birds is the most likely cause for many populations. All of the earlier issues I mentioned set off little red flags in my brain, but as someone who’s studied how plants, animals, and diseases spread, changes in range and migration patterns set off big warning bells. Messing with the physical location of species tends to wreak havoc in ecosystems, and though I’m not a bird expert and can barely guess what changes have occurred due to these behavior changes, I’m not excited about contributing to this experiment, even though those feeders were adorable.

While all this research has convinced me not to put a bird feeder in my garden, it leaves out the main reason other people choose to have them- they like to see birds. Just like owning a dog doesn’t make economical or environmental sense, there are other, more social benefits to having animals around to entertain us. My squeamishness about causing ecological change may also be misplaced, since gardening is at its heart, creating my own little ecosystem. I think I’ll take the middle ground this time though- I’ll design the plants in my garden with feeding the birds in mind, with native berries, seeds, and flowers making a strong showing and a clean pool of water in the bird bath year-round. Maybe I’ll even get those little bird feeders, but hang them empty as garden art and let the plants feed the birds.

References

[1] M.C. Brittingham, S.A. Temple, “Does Winter Bird Feeding Promote Dependency?,” Journal of Field Ornithology, vol. 63, 1992, pp. 190-194.

[2] E.H. Dunn and D.L. Tessaglia, “Predation of Birds at Feeders in Winter,” Journal of Field Ornithology, vol. 65, 1994, pp. 8-16.

[3] G.N. Robb, R.A. McDonald, D.E. Chamberlain, and S. Bearhop, “Food for thought: supplementary feeding as a driver of ecological change in avian populations,” Frontiers in Ecology and the Environment, vol. 6, Nov. 2008, pp. 476-484.

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