Date: 7/6/26 12:17 pm From: ed pandolfino via groups.io <erpfromca...> Subject: Re: [centralvalleybirds] Purple martins in the Valley again?
And another, potentially important difference between western and eastern Purple Martins is their non-breeding range. Though the sample size is small, a geolocator study in 2012 (Fraser et al. 2012. Proc. RoyalSoc. B. 279:4901) showed that eastern martins wintered mainly in the Amazon Basin, where most of the habitat is intact, while the western birds they tagged wintered in the Atlantic Coastal Rain Forests in eastern Brazil, where the habitat is now present only in isolated fragments (mainly due to enormous sugar cane plantations).
Ed PandolfinoSacramento, CA
On Monday, July 6, 2026 at 11:58:40 AM PDT, Dan Airola via groups.io <d.airola...> wrote:
Useful summary of the genetics study by Alan Baker, Alvaro. Genetic work on the whole North American population is underway now, being conducted by PhD student Victoria Wiley at Columbia University. She presented a brief progress report on her work to the California Purple Martin Working Group last month. I don’t want to try to summarize it for fear of getting it wrong, but my impression was that it largely confirmed the current subspecies separations but showed some separation between Western martins between the Pacific Coast and the Rockies and interior mountain ranges (which Baker was working on, but died before he published).
If anyone is interested in joining the working group, PM me. We meet 2-3 times/yr via zoom
Dan AirolaConservation Research and <Planningd.airola...>/494-1283
On Jul 6, 2026, at 11:39 AM, Alvaro Jaramillo via groups.io <chucao...> wrote:
All
A perspective of the importance of Western Purple Martins. There was a paper done some time ago now (2007) that showed the genetic distinctness of the Western Purple Martins vs the Eastern birds. Note that they did not sample the desert nesting population from US/Mexico. This study having been done a while ago is much less informative than the type of genetic work that can be done today (genomics), it was restricted to mitochondrial DNA which has plusses and minuses. It would be superb to have a modern genetic study, and also include the desert birds as well as perhaps the entire Progne (large martins) genus, with multiple populations sampled. The study suggested that the split might have happened 400,000 years ago between eastern and western. There was some evidence of some eastern genes in British Columbia birds. Yet, not a lot from what I could read. Cutting to the punch line here, martins of different species are quite similar, some nearly impossible to separate in some plumages (usually the adult male plumage). The fact that eastern and western Purple are similar looking (females are separable though), is not unusual in this group. But knowing that they are well separated genetically is intriguing. With further work they may prove to be different species, at least the published data so far does not exclude this possibility. If so, the importance of conservation of the Western Purple Martins becomes even greater as they are perhaps more unique than have been given credit for.
Alvaro
Alvaro Jaramillo
<alvaro...>
www.alvarosadventures.com
From: <centralvalleybirds...> <centralvalleybirds...> On Behalf Of Steve Hampton via groups.io
Sent: Friday, July 3, 2026 9:12 AM
To: <centralvalleybirds...>
Subject: Re: [centralvalleybirds] Purple martins in the Valley again?
I'll add a few more observations from the Pacific Northwest.
- There are lots of Purple Martins but they are largely limited to using artificial nest boxes over or very near (within 20 yards) the water (e.g. at marinas). They are very rare in natural contexts.
- Build it and they will come - when new boxes are installed, they are often fully occupied within one or two years, implying that there is a shortage of suitable breeding cavities and many floaters in the population. This is not surprising, as waterfront homeowners and land mgrs (e.g. local parks, etc.) readily remove snags. Most of the waterfront areas are manicured to some degree.
- Starlings aren't a huge problem here. Because the starlings nest earlier, they are typically feeding young by May 1, when the martins arrive. At our nest box arrays, we either don't install them or we keep doors over the entrances until May 1. However, even it we neglect to do that, starlings are not necessarily a problem (at least in more rural areas). Some of our nest box arrays are installed and managed by older volunteers who do not manage to pass on mgmt to others before they become unable to care for the boxes. Thus, quite a few nest box arrays are abandoned by their human caretakers. At these, starlings typically occupy only one or two boxes out of six to fifteen present, with the martins in the rest. Perhaps in more urban areas, where there are more starlings, this could be a problem -- though it is easier to find people to oversee the boxes there.
- If nest box arrays are put up too far from the water, the martins aren't interested in them and the boxes may be used by House Sparrows and/or starlings.
- Kestrels and merlins (we have local nesting black merlins here) are not too much of a problem either. A colony of 6 pairs of martins seems to be sufficient for them to gang up and attack and chase away a merlin (yes - I've witnessed that).
- Because neonic pesticides are largely confined to commercial ag (with most use in the Corn Belt and in Calif's Central Valley), it does not seem we have that problem here, though it is difficult to tell. For more on how neonics are wiping out even American Robins and Red-winged Blackbirds in the Corn Belt, see eBird trend maps, which I summarize at my Substack post here: Silence in the Corn Belt.
I'm not sure if any of this is helpful for the Central Valley.
On Thu, Jul 2, 2026 at 10:42 PM Dan Airola via groups.io <d.airola...> wrote:
Translocation won’t solve the underlying problem of lack of sufficient insect populations. It could also mess up the genetics. Permits would be required and almost surely wouldn’t be granted.
Populations, although local, appear to be pretty healthy in the coastal forest region (Marin north to Del Norte county).
The real solution seems to be to further restrict neonicotinoid pesticides and let the prey base recover, and the martins will follow. Remember that Sacramento had the largest colonies in western North America in the early 2000s, decades after starlings were established as breeders there. If we don’t lose the tenuous source population and bring the insects back, it could happen again. But starling competition would still be a problem in rural areas that support more starlings. There it will take a gradual expansion to starling proof nest boxes from the few source populations, a multi-decade proposition
Well that’s probably enough about martins for the next year or so!
Dan Airola
Conservation Research and Planning
<d.airola...>
916/494-1283
On Jul 2, 2026, at 7:20 PM, Larry Montgomery via groups.io <telemark22...> wrote:
If Puget Sound is the closest healthy population, do you assume capture and reintroduction would be necessary? Otherwise, I would think it would be good to have similar safe spaces constructed continuously down through Oregon and Northern CA. That would be worthwhile, but a very slow way to bring them back, which is, indeed, a worthy goal.
Larry Montgomery
Sacramento (but sweltering in Maine at the moment)
