Denise and David Hamilton
Hi all, A quite a while back I asked if anyone else is seeing less numbers of White-tailed Kites and G. Eagles while out birding. Thank you to all those who responded! Below are all the responses I received if you care to read them.
It is my impression that White-tailed Kite populations are volatile.
They certain can exploit vole population explosions: I've seen 76 in a
single roost at Pt Reyes during a vole eruption. So they can move
around. We're coming off (hopefully) a nasty multi-year drought as well.
Just from my personal observations: I am still seeing lots of White-tailed Kites. I see them in Sonoma & Solano Counties regularly. But during raptor counts during the migration along the Sonoma Coast I did notice less Kites this year then in past years. Probably due to rodent populations.
As for Golden Eagles. I also see them, I would say more then in the past in both Sonoma, Lake, & Solano counties as well. I don't do a lot of Napa birding. In fact I saw an adult Golden Eagle today along the Hwy 101 corridor between Petaluma and Cotati.
It is well known that Bald Eagles do in fact tend to push out Golden Eagles where the habitat is more suited for Bald Eagles. This may simply move Goldens back to their more suited habitat as well or may help keep population in check?
i have pictures from sept 2009 of 30 kites on fenceposts, together.
i have pictures of 10-12 on one tree at tolay lake, probably also in september.
there are often kites at the area betw shollenberger and ellis creek, and also las gallinas sewer plant.
I do not generally respond to birding emails, but I just returned yesterday from 5 days of traveling (not all birding) through parts of Santa Clara, Alameda, Sacramento, Yolo, Napa, Sonoma, Marin, SF and San Mateo Cos. without seeing either a White-tailed Kite or a Golden Eagle. I ran into a couple claiming to have seen Golden Eagles flying over Bodega Head (I saw TVs near in time.)
In fact, I made four driving trips to No. Cal. in 2014 without seeing either a White-tailed Kite or a Golden Eagle, other than a WT Kite at Kern NWR in mid-November.
I blame all disappearances on people, without a showing of proof, for destroying "good" habitat and creating "bad" habitat -- good habitat for ravens, crows, Cooper's Hawks and other adaptable creatures that distort the natural order. In mass, we are generally oblivious to the consequences of our actions.
I do monthly Raptor Surveys in Madera, Merced and Mariposa counties on a regular basis. There were fewer raptors in general this last year which in my opinion is due to less prey due to drought, over grazing and habitat loss for both prey and predator. We have especially noticed a lack of kites and harriers in areas where we would see them on a regular basis in prior years. This last year we noticed a drastic drop in raptor numbers as the summer approached and on through the fall. Many of the fields were over-grazed plus many of the grassland areas on our routes had a change in use to agriculture.
I am a volunteer survey participant so this is just an opinion from being involved for the last 5 years. We have noted that as the grasslands were revived by the rains and the rodents and insects returned that the numbers are slowly improving ( winter surveys in general usually produce higher counts though), However the numbers have not increased to the previous years totals.
As far as eagles we have noticed a change in numbers but we still get about the same ratio of Bald vs Golden overall.
I work on a vineyard near Paso Robles from August-October each year. In 2011 there were barn owls nesting or roosting is every one of the 360 boxes on the 2300 acres. In 2014 I saw three roosting in boxes. There were still barn owls to be seen flying at night, but I’m thinking the drought is the major cause. In 2013 I saw a shocking number of instances where great horned owls had eaten barn owls, but It seems as though that happens because the great horned owls are also under strong pressure from the same forces. Here in the Sacramento area I have been seeing lots of peregrine falcons and prairie falcons this year, and have seen a couple times that what a peregrine seemed to have been eating was a kite. I have not noted any decrease or increase in sightings of golden eagles.
White tailed Kites have not diminished in Marin's Lucas Valley over the years. Eagles have never been prevalent here.
My thoughts are that the proliferation of power lines and urban sprawl means that Red-tailed Hawks can now out-compete those raptors that hunt from the air. Red-tails hunt from perches in tall snags and on power poles. Harriers, Kites, Rough-legged Hawks, and Golden Eagles hunt from the air--aerial-platform-hunters versus stationary-perch-hunters. Ranchettes means that the large expanses of open country have been subdivided into smaller and smaller fragments--perfect for Red-tailed Hawks.
I wouldn’t call this sold statistical evidence, but if you look at a species map on ebird and compare the number of locations that White-tailed Kites and Golden Eagles were found in 2014-2015 versus 2013-2014 you will see that there were many more White-tailed Kite sighting locations in 2013-2014 than there were in 2014-2015. For Golden Eagles there were a few more sighting locations in 2013-2014 versu 2014-2015. This does match your experience.
I had been meaning to post a query about white-tailed kites myself. They are normally fairly common/abundant in southern Sonoma County and frequent the same spots year round; there is a pair in my neighborhood (they have regularly fledged 2 broods a season for many years), a pair in the park (Crane Creek Regional Park) where I walk most days, and numerous individuals that I regularly see around the area. For at least the past month though, and probably quite a bit more, I hadn't seen or heard a single one anywhere. I was wondering what could have wiped out every kite in the area without touching the other raptors--I continue to see Red-tail hawks, red-shouldered hawks, kestrels and harriers as often as ever and in all the usual spots. Then this morning on my walk in Crane Creek, there were two kites perched together in an oak. Later, as the fog lifted, I saw them hunting & heard their calls. I'll be curious to see if the others reappear . . . Does anyone have ideas on what is going on with them?
The tallies for White-tailed Kite and Golden Eagle for the Sonoma Valley CBC were definitely low this winter. We counted 36 kites which is 50% of the preceding nine-year average and a new all-time low (versus the record high of 118). We recorded four Golden Eagles, 56% of the preceding nine-year average and the lowest total since the first two years of the count.
In May 2014 there was a report in the Davis Enterprise newspaper about a new potentially fatal mite disease affecting our local Golden Eagles.