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| From Grassland songbirds in a dynamic management landscape: Behavioral responses and management strategies by N.G. Perlut, A.M. Strong, T.M. Donovan, N. J. Buckley |
The data is the reproductive success for a single year, not life-time success. So a success rate of 2.0 MIGHT be replacement if the birds live for several breeding seasons and yearling mortality is not excessive.
Both species require a 65 day interval to successfully hatch and fledge their young.
Every species and seedline of forage has its own, optimum time for cutting. In general, there has been a very strong trend away from later-maturing forages and more frequent cuttings of hay fields.
For instance, Timothy was the default grass species for much of the east for hay. Timothy grass pollinates at about 1500 Growing-Degree-Days which is when most farmers would cut it. In Michigan, that falls at the end of June or very early-July.
More recently, Orchard Grass has been a popular choice for hay. It pollinates during the first week of June...which is when farmers will go out to cut hay.
This is a small thing and almost invisible to city-folk, but it makes a huge difference to the birds.
Management Intensive Grazing was also looked at. Savannah Sparrows had a reproductive success of 230% and Bobolinks had a reproductive success of 180%.
Translating the data to other locations
I looked through my blog to see if I could identify some clear markers for the two later dates on the chart. June 20 in Ithaca, NY is not the same from a biological standpoint as June 20 outside of Louisville, KY.
June 20: 600 GDD-b50. Orange daylilies are blooming in most, roadside ditches. Most elderberry bushes are in bloom. Chestnut trees are blooming.
July 1: 1000 GDD-b50. Very first Japanese beetles spotted. Potato beetles populations are spiking.
My understanding (and someone correct me if I'm wrong) is that orchard grass is a really poor substitute for timothy. Livestock will shun it in favor of timothy. I was told this by a Vermont dairy farmer with 50+ years of experience. The definition of horsepower developed by James Watt was supposedly based upon the amount of work a draft horse on a diet of timothy hay could perform throughout a day.
ReplyDelete"In the British Imperial System, one horsepower equals 33,000 foot-pounds of work per minute—that is, the power necessary to lift a total mass of 33,000 pounds one foot in one minute. This value was adopted by the Scottish engineer James Watt in the late 18th century, after experiments with strong dray horses, and is actually about 50 percent more than the rate that an average horse can sustain for a working day."
Timothy is preferred feed, certainly for horses. I suspect for the following reason:
"Timothy is unique among grasses in that during the autumn it develops a corm, a bulb-like structure from an elongated internode. Water soluble carbohydrates, mainly fructans (chains of fructose sugars with a terminal glucose sugar) fill the corm in the spring past the flowering stage."
What you say is true. Timothy is one of the best grasses. However, for reasons that I sometimes could or could not determine year after year different grasses, and different varieties of all crops; corm, alfalfa or clover or trefoil or varieties of apples and cherries, or garden vegetables would do better than the others. And usually for no discernable reason. So that's why I , and most other old farmers that I have ever known plant different varieties things that will do well together and be able to provide crops when the other varieties didn't do as well. My rule is never plant just one variety of anything in the woods, orchard, pasture, hay field or garden. That way you will not have a total crop failure. ---ken
DeleteWhich is why the "pasture mix" I used to use was a mix of timothy, red clover, and trefoil.
DeleteEven then, orchard grass crept in, as did a certain amount of alfalfa. Nature will convert monocultures into mixes for fields that aren't tilled annually. And beginning tilling tends to bring up the weed seeds that lay dormant for multiple years.
Where I used to farm, getting enough drying days was hit-or-miss, which is why fields heavy in clover and alfalfa were difficult to get high quality hay. If you can't get it dry, your bales are going to mold.
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