I have received numerous questions regarding White-crowns "Gambel's and 
Eastern races, ticks, etc.  Hopefully this will help some.

  From Hilton, B. 1991 article for WildBird magazine
Since 1982, I've banded birds at Hilton Pond near York, SC, and through 
mid-April of this year I've handled 17,018 individuals from 110 species. 
During my first 18 months of banding, I detected no large ectoparasites on 
the first 1,700 birds, but in the winter of 1983-84 I found ticks on the 
heads of three Purple Finches, two Dark-eyed Juncos, a Field Sparrow, and a 
Carolina Wren. I was curious about this, but seven parasitized individuals 
out of another 2,000 birds didn't strike me as a major threat to the local 
avifauna.

The next winter (1985-86), there seemed to be even fewer ticks, with only a 
Rufous-sided Towhee and a Purple Finch showing parasites, and the winter of 
1986-87 was similar with just one Northern Cardinal and two Purple Finches 
carrying ticks. In strong contrast, since 1987-88 ectoparasites have 
increased drastically, and if the past winter of 1990-91 is typical of 
what's to come, ticks soon may be infesting Carolina birds in epidemic 
proportions. Of 345 Purple Finches I banded in 1991 from January through 
March, 41 of them were tick-infested--almost as many in one winter as the 
49 I caught with ticks in all the years from 1982-90!

Albert Conway, a fellow bander who has studied birds for more than 50 
years, sees a similar increase in ticks on birds he bands at Catawba, SC. 
Conway's grassy property is more open than mine and he gets more Dark-eyed 
Juncos. In 1987-88, 13 of his 51 juncos had ticks--an incredible 25% 
infestation rate for the species.

I'm in a quandary to explain the apparent increase in tick populations in 
Upstate South Carolina. My guess is that three relatively mild winters in a 
row have failed to knock back ticks that usually lie dormant all winter in 
the soil and most often succumb to cold weather. (In that regard, wouldn't 
it ironic if one of the first natural indicators for global warming turned 
out to be the tick!)

Among 17,018 birds banded, I've detected ticks at Hilton Pond on 157 
individual birds from 16 species, which is about a 1% infestation rate. As 
might be expected, most ticks occur on ground-feeding birds, and if I 
include only those types and ignore the warblers, kinglets, and more 
arboreal species, the rate comes closer to 2%. Since 1982, I've found ticks 
on the following:
Purple Finch (90 birds)
House Finch (18)
Northern Cardinal (15)
Dark-eyed Junco (15)
Rufous-sided Towhee (8)
Field Sparrow (2)
Blue Jay (2)
Song Sparrow (1)
American Robin (1)
Brown Thrasher (1)
Northern Mockingbird (1)
Carolina Wren (1)
Fox Sparrow (1)
White-throated Sparrow (1)
American Goldfinch (2 recaptures only)
Tufted Titmouse (1 recapture only)
Arachnologists--specialists who study spiders, mites, ticks, and their 
kin--have described several species of avian ticks. Some appear to infest 
only birds, while others spend parts of their lives on small mammals such 
as rodents and rabbits. One apparently bird-specific tick (Ixodes brunneus) 
was reported by the late Charlie Blake from 11 kinds of birds he banded 
near Durham, NC. I suspect it is this species that shows up most often on 
my birds at York. A few local birds, however, have borne the deer tick--a 
species known to cause Lyme disease, or "tick arthritis."

There's little doubt a tick can be detrimental to its bird host. Nearly all 
ticks I've seen on birds have been attached near eyes, ear canals, crowns, 
or foreheads--the sorts of places where a beak can't nip. A bird probably 
has trouble scratching off ticks with its claws, so it's easy for the 
parasite to hang onto a bird's head while taking a blood meal. (Some ticks 
become so engorged with blood that they're visible on birds at feeders; if 
you encounter ticks on birds--especially on species other than those 
mentioned in this article--please send that information to the "Letters" 
column at WildBird. Also mention the geographic location and time of year.)

I've caught several Purple Finches with up to four ticks, but the 
record-holder was infested by a grand total of eight--all swelled to more 
than 3mm in diameter. Several ornithologists and parasitologists I've 
talked with are undecided about whether these ticks transmit diseases from 
one bird to another, but just the blood loss caused by eight ectoparasites 
around a bird's eyes and brain probably can disrupt normal activities.

When I first captured that eight-tick purple finch, I removed all the ticks 
and preserved them in alcohol. I also banded the bird, noted that both sets 
of eyelids were swollen nearly shut, and released the finch with little 
hope of seeing it again. I was pleasantly surprised when this particular 
bird hopped into my traps two weeks later. On close examination, I found no 
new ticks, and the fact that the bird's eyelids were in perfect shape was 
all the rationale I need to continue plucking parasites from every bird I 
catch.


  I haven't gotten the tick IDed yet.
Jeanette sent a couple cool pictures (and the above article) from a banding 
station in South Carolina with Purple Finches with a very engorged 
ticks.[See photos below]
Cheers
Dave