Date: 5/5/25 7:22 am From: Pete Sole <pete...> Subject: Re: [MBBIRDS] This year's migration numbers/lateness
Hi Abram,
Thanks for the insight! Much appreciated.
I wonder though, given the variability over time, if the averages are
even representative of the data. Not to get in the weeds on the math,
but if the standard deviation is high, then looking at the average could
easily lead to wrong expectations. One example, I wonder if El Niño, La
Niña, and in-between years, lead to noticeably different migration
patterns (numbers and timing), given their effect on weather (rainfall).
Many factors to ponder. Some quite complex with feedback loops and
subtle downstream impacts. Yet somehow, the birds still manage to
migrate. 🙂
Thanks again for sharing,
Pete
On 5/5/25 6:39 AM, Abram Fleishman wrote:
> Hi Carol and Pete,
>
> The historical lines on birdcast come from the 1995-2017 period. As
> with any average, there are high years and low years and the average
> draws the line through the middle. There may even be average years
> that the line represents really well. But I like to think about our
> rainfall in Santa Cruz county (or California in general) when thinking
> about this stuff. With our rainfall, we normally have wet years or dry
> years and both of which are quite far from the average rainfall. Only
> occasionally do we get years that hit the average.
>
> I imagine the same thing is happening with bird migration. There are
> many contributing factors like the previous breeding season’s
> reproductive success, the fall migration and then winter survival
> rate, and then spring migratory corridor and survival. All these are
> affected by weather (storms can kill, but rains lead to strong food
> resources, winds and storms can push and pull birds during migration)
> along with a host of other factors. This is all just to say that
> averages are just one piece of info, to ask the question of how this
> year stacks up to past year we would need to seem more data.
> Specifically yearly values or trend lines.
>
> The birdcast team has put some great info here:
> https://birdcast.info/about/review > <https://birdcast.info/about/review/?_gl=1*m513m6*_gcl_au*NDUyMDExOTM0LjE3NDU1NTYyMTA.*_ga*MTk0OTIyMDUwMy4xNzQ1NTU2MjEw*_ga_QR4NVXZ8BM*czE3NDY0NTA3MDYkbzIyJGcwJHQxNzQ2NDUwNzI5JGozNyRsMCRoMA..> >
> Hope this helps interpret the birdcast info,
>
> -Abram
>
> Sent from my phone
>
>
> On Mon, May 5, 2025 at 00:48 Carol Pecot <carol.pecot...> wrote:
>
> Good thoughts, Pete, thanks. Thanks also for mentioning the 7
> simple actions link, it is a good one! Jane Orbuch made some
> posters in a larger format, and we usually display them at birding
> events. On the topic of planting natives = more caterpillars =
> more baby bird food, Doug Tallamy’s Homegrown National Park park
> is awesome: https://homegrownnationalpark.org/.
>
> By the way, this coming Saturday will be a small Migration event
> at Natural Bridges. If anyone is interested in helping in some
> way, please contact me.
>
> Carol
>
>
> > On May 4, 2025, at 9:59 PM, Pete Sole <pete...>
> wrote:
> >
> > Hi Carol,
> >
> > I'm no expert. I don't know how far back the "historic" data
> goes. But my suspicion, is that data older than perhaps 10 or 20
> years, reflects migration patterns that may no longer be present.
> That is why when I look at data on ebird to try to tease out
> trends, I try to limit the data to the last 10 years. If nothing
> else, we know that land use and climate patterns have changed
> significantly in the last 50 years. Not to mention the estimates,
> that we have lost some 2.9 billion birds in North America since
> 1970. (source: https://www.birds.cornell.edu/home/bring-birds-back)
> >
> > Regardless, here are 7 suggestions to help avian species:
> >
> > https://www.3billionbirds.org/7-simple-actions > >
> > My 2 cents,
> >
> > Pete
> >
> >
> > On 5/4/25 8:57 PM, Carol Pecot wrote:
> >> I was looking at the BirdCast dashboard (
> https://dashboard.birdcast.info/region/US-CA-087) and saw that the
> graph of the “Total Birds Crossed” seems to show about 1/2 the
> number of birds compared to the historic amount for our county.
> Does that seem correct, or might that be a late migration that
> people have been mentioning? If late is the case, then maybe it
> will continue rising more steeply…?
> >>
> >> Does anyone have other information on this?
> >>
> >> Carol Pecot (We now have M & F BH Grosbeaks, and got a
> Wilson’s Warbler about a week ago)
> >>
> >
>
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