A Mite-y Big Problem at Flycatcher Nest

I dislike unhappy stories and enjoy writing about them even less. However, I have to remind myself that not everything is about the birds — Mother Nature is a much more clever scriptwriter than that.

I mentioned in my last post that there were some moving specks on the vinyl siding behind the nest that I suspected might be some kind of bird mite. Here is what my research found.

At the end I share my opinions as to the effect that the mites had on the nestling development and their departure from the nest.

Visual Evidence of Mites

I went back and looked at video footage to look for evidence of moving specks which I would later confirm to be mites. It turns out that a good way to see them is to fast-forward the video and watch closely — the mites are easy to see when moving, especially those on the light coloured vinyl siding.

I found the first mite evidence in the July 19 webcam footage — (hatch-day + 8). On subsequent days, the quantity of mites increasing dramatically, dare I say ‘exponentially’, until the three nestlings left the nest on July 23. While the initial mites were only seen while moving on the vinyl siding, by July 21 large immobile clusters of mites could be seen on the outdoor light fixture.  Here is a picture taken on July 22 with my Panasonic FX-200 camera:

Mites on the Light Fixture

Mites grouping on the outdoor light fixture.

The out-of-focus mites are still visible on the siding behind the nest. More obvious are the the brown patches on the black edge of the light fixture in which individual mites are easily visible. The reddish-brown colour comes from mites that have all taken some blood, probably from one of the nestlings (’empty’ unfed mites are light coloured).

To study the mites more closely, I ran a lint roller along the edge of the light fixture. This was surprisingly effective at removing all of the mites in its path. The sticky lint-roller paper immobilized most of the mites however there were still a number of wandering mites so I sprayed the sample with a mixture of bleach and water to make sure the mites were dead before the sample came into the house.

To demonstrate the mite size and numbers, I took a picture showing a section of lint-roller paper with mites next to a Canadian dime:

Mite Sample

Mite sample acquired using a lint roller.

A dime is about 1.8 cm in diameter so I estimate the density of mites in the high-density area along the top of the sample to be about 200 per square centimetre. After the nestlings had left the nest, there was extensive coverage of the light as well as 4 or 5 patches of packed mites on the siding. Estimating the visible coverage at around 200 square centimetres that would mean about 40,000 mites. This is just the visible areas and the hidden areas on the light fixture. Any mites on the nest or the nestlings are not included though one might expect both to be heavily infected. My best estimate for the total mite count is somewhere between 50,000 and over 100,000.

We have a Wild M11 microscope which I used to get a better look at the mites. Using my iPhone camera, I was able to take some surprisingly good pictures. The following image was taken at the lowest (4X) magnification:

IMG_1757

The wire has a length of about 2.2 mm at this magnification (calibrated with a plastic ruler) making the mites’ length about 0.6 mm. The next image was made at the next highest magnification (10X).  Unfed mites are clear so this looks like a mite that has fed on blood — nestling blood most likely.

IMG_1755

Identification

The two most common North American bird mites are the Northern Fowl Mite (Ornithonyssus sylviarum) and the Chicken Mite (Dermanyssus gallinae) which goes by several other names such as the Red Mite, Red Fowl Mite and Red Poultry Mite. Both are of great interest to the poultry industry because of the costly damage they can do. Both can infect wild bird species. From various sources I have read, I concluded that the flycatcher nest was probably infected with the Northern Fowl Mite.

 

The best reference that I found summarizing issues around bird mites and humans comes from a 2010 document from the PennState, Department of Entomology series of short Entomological Notes simply titled BIRD MITES (accessed July 28, 2017).  Below, I quote a few of the more relevant paragraphs and highlight important sections that helped me handle the flycatcher mite infestation:

Bird mites are very tiny, flattened parasitic arthropods in the order Acari. They belong to two closely related genera in two families; Dermanyssus species in Dermanyssidae (Fig. 1), and Ornithonyssus species in Macronyssidae. Bird mites have piercing mouthparts that enable them to take blood meals from their bird hosts. Although the mites will inadvertently bite people, they cannot reproduce without their bird hosts.

DESCRIPTION

Bird mites have five stages: egg, larva, protonymph, deutonymph and adult. The larvae have three pair of legs; the nymphs and adults have four pair. Adults are about 0.7 to 1 mm in length and are just barely visible to the naked eye. Unless they are moving, they are extremely difficult to see. The color is translucent white until they take a blood meal after which the mites are reddish mahogany to brown. Mite eggs are white, oval and cannot be seen without the aid of magnification. The same applies to the larvae and nymphs.

LIFE HISTORY/BEHAVIOR

Most bird mite species can complete development in five to twelve days with optimal temperatures and host presence. This short life cycle makes it is possible for mite populations to attain tens of thousands of mites in bird nests during the rearing of young birds. If the population is too large (or if the fledglings vacate the nest or perish), the mites will migrate in mass to locate an alternative host. It is during this migration that mites can and do enter the living quarters of people. Some mites (i.e. Dermanyssus gallinae, the chicken mite) can survive for several months without taking a blood meal; the northern fowl mite, Ornithonyssus sylviarum, for several weeks. However, the mites do not appear to survive for more than several days in the reduced humidity (<35%) environs typically found in air-conditioned or dehumidified homes.

MANAGEMENT

Birds should be discouraged from building nests in or adjacent to buildings. Close all openings large enough for birds to enter attics, sof ts and similar areas. Install hardware cloth, sheet metal, or other materials to prevent birds from nesting and roosting on porches, breezeways and other exterior sites. Disrupt nest-building efforts by removing partially completed nests in shrubbery and on air conditioners and windowsills.

If mites are detected in the structure, locate the bird nest source. Remove the nest.

My take home message was to monitor the mites both around and away from the nest and be prepared to remove the nest and sanitize the nest area once the nestlings had left the nest to prevent the host-less mites from moving inside the house looking for new targets. I read some accounts of the problems that resulted from houses that became infected by bird mites (readily available on the websites of many extermination companies) and they definitely made me want to keep the mites outside.

Of Mites and Nestlings

Beside the visual evidence of an exploding mite population, the nestlings became increasingly restless as the quantity of mites increased. Frequent episodes of scratching were noticeable on the webcam videos.

My personal belief is that the nestlings left the nest early, before the were ready to fledge, in large part because of their discomfort from the mites. I know that one nestling perished because I found the body on the morning of July 24. The last sighting of a nestling was on the morning of July 25. The last sighting of the female adult sticking close to its foraging area near our house was on July 25.

One final reason why I do not think that there were any surviving nestlings was the presence of a domestic cat nearby. The day that I found the dead nestling, it was lying in our driveway when I returned home from some errands. I have seen the cat, before and since, in and around our yard. An unfledged nestling hopping in the bushes would have had little chance of avoiding the feline if it were spotted.

 

 

References

I have listed below some of the interesting references that I found online.

[1] This 2005 reference contains some good high-level information on mites: Common Lice and Mites of Poultry: Identification and Treatment.

[2] One of the best short summaries on bird mites that I have found: UW Madison Department of Entomology information sheet.

[3] Good reference from Iowa State University: Bird-Mites.

[4] A good 2014 review article: Mites and birds: diversity, parasitism and coevolution.

[5] A 2014 research article looking at some of the relationships between birds and mites: Repeatability of Feather Mite Prevalence and Intensity in Passerine Birds.
[6] Slides from a presentation showing the Poultry Industry’s views on Northern Fowl Mites.
[7] Washington State University research proposal and status: ORIGIN AND SPREAD OF THE NORTHERN FOWL MITE: A LANDSCAPE GENETICS APPROACH.
[8] Google Books textbook chapter: Global Diversity of Mites.
[9] Countryside Daily article with some information that I did not find elsewhere: Chicken Mites & Northern Fowl Mites: Controlling Infestations.

Pacific-slope Nestlings 10 Days Old

July 21: As of yesterday the Pacific-slope Flycatcher nestlings are 10 days old. Their eyes are opening and feathers are starting to show. They also appear much more restless than in previous days and I’m a little worried that one might fall out of the nest. It’s more than 6 feet down to the concrete steps so a fall would, I imagine, be fatal.

The adult birds spend most of their time foraging and only at the nest for a few seconds every few minutes. So, I thought that I’d try to get a better between-visits picture of the nestlings with my Panasonic FZ-200 camera whose 24x optical zoom lets me fill the image whereas the Logitech 920 webcam, used for my videos, has no optical zoom so cropping is the only way to “zoom in” and that results in a lower resolution image. Here is the best picture that I was able to take:

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I had just focussed on the nestlings, who were alone in the nest, when the adult male flycatcher appeared in the foreground. Because of the low-light I was using a large aperture with poor depth of focus which put the adult bird slightly out of focus. It’s a nice subtle effect.

The camera picture also highlights something else not so nice. If you look closely at the vinyl siding behind the nest you can see a number of small black specks. Reviewing the webcam videos shows that these specks are actually moving around. They are concentrated around the nest suggesting that they are some form of parasite associated with nest and birds. I reviewed previous days’ videos but July 21 was the first day that the specks were visible. My suspicion is that they are bird mites which Doctor Google tells me would not be a good thing. More research needed.

Pacific-slope Flycatcher Nest

June 26: This was the day that we noticed the nest being built on top of the light in our front entry way. Our first thought was a swallow because we have a lot of them flying around our neighbourhood though most would have nested weeks earlier.

June 28: We noticed a bird sitting on the nest so I got out my camera and we discovered a Pacific-slope Flycatcher (whose 4-letter species ID is PSFL) sitting on the nest. Here is the picture that I took:

PSFC Nest P1180287

Consulting with Birds of North America Online (BNA-online) I discovered that first broods occur in April or May but some pairs will attempt a second nest around June or July. This was clearly round 2 for these birds.

June 30: I got up on a step-stool, held my iPhone 4s above the nest and took a picture:

IMG_1742

The PSFL was sitting on 3 eggs. Consulting BNA-online again I found out that the most common number of eggs is 4 followed by 3 so we might have a full nest or there may be more to come.

July 2: Only 2 days after the first picture, I took a second and discovered that there were still 3 eggs.

July 5: Another 3 days and there were still only 3 eggs to the bird sitting on the nest was probably incubating the eggs. BNA-online indicated typical incubation periods of 13 to 16 days so, assuming that my first ‘egg picture’ indicated the start of incubation then we should expect the eggs to hatch between July 12 and 15.

July 11: A picture from my iPhone shows that the eggs have hatched:

fullsizeoutput_1f10

The three ‘grubs’ in the nest look pretty helpless so they must have hatched quite recently.  I decided to call July 11 hatch-day 0.

Here is my first video of the adults coming and going, bringing food to the nestlings.

There will be many more videos and pictures to come as the nestlings grow up and fledge. I just hope that they all make it to fly away risking the odds of survival which are not in their favour — I’ve heard that only about one in ten birds survive a year after hatching.

Gulls Eating Sea Stars

Back in August of this year, the 14th to be exact, I was walking along the waterfront in Sidney, BC when I caught a gull red-handed (or red-billed) trying to swallow a sea star. Here’s the sequence of 4 pictures that I took over a half-minute or so:

Gull Eating Sea Star 1 of 4 - P1170385 Gull Eating Sea Star 2 of 4 - P1170386

Gull Eating Sea Star 3 of 4 - P1170387 Gull Eating Sea Star 4 of 4 - P1170388

The gull does not seem to be having a lot of success.

Then, I was looking through some older images yesterday and found another sequence of 4 images taken in March 2016 at Neck Point Park in Nanaimo:

Gull Swallowing Sea Star 1 of 4

Gull Swallowing Sea Star 2 of 4 Gull Swallowing Sea Star 3 of 4

Gull Swallowing Sea Star 4 of 4

The first image shows the gull with the sea star in its mouth. The following three images show the gull swallowing the sea star. It had to extend its neck which, as you can see by the white spot on the rocks appearing in the third image, triggered a ‘movement’.

Unexpected Finds at Buttertubs Marsh

I was birding Buttertub Marsh with a friend last Thursday (November 17, 2016). We were scanning the almost empty pond for waterfowl when Leonel noticed 4 Great Fronted Geese hanging out with some Canada Geese at the far side of the pond. It was the first time that I had seen them there.

Here’s a picture captured with my Panasonic FZ-200 at maximum zoom. It’s cropped as well. You can also see a bird in front just to the right of centre with a neck-band as well. I’ll say more on this guy later.

GWFG at Buttertub Marsh

Four Greater White-fronted geese mixed with some Canada Geese at Buttertub Marsh on November 17, 2016.

About and hour and a half later we were just about done and noticed the Canada Geese swimming more in the middle of the pond without the GWFG. It was Leonel’s good eyes and my FZ-200 to the rescue a second time. The 4 geese were across the pond on the edge of the pond resting, their coloration blending in well with the background reeds.

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VIU Canada Goose Project

I said that I’d come back to that Canada Goose with a neck band in the first picture.

A group from VIU, headed by student Stew Pearce, banded 200 Canada Geese earlier this year and has been following the locations where they have been seen since using information sent in by birders or anyone else interested in helping out. The goal is to learn how the birds move about during the year. You can find out more by going to the VIU Canada Goose Project web-site.

Stew told me recently that geese from the project have been seen and reported from as far away as Portland, Oregon. So, if you happen to see a Canada Goose with a neck band let Stew know using the instructions at the above link.

So, did I figure out what the ID of our find was? Yup! We saw the bird swimming behind some reeds an hour or so after our first encounter and I took a some pictures as the goose swam in and out of view. One of the four was clear enough to ID the goose:

p1170964

 

Our goose’s ID was “096P”. I checked the web-site and discovered that the most recent sighting was November 6 at Buttertubs Marsh. I’m guessing that this guy is not going South this winter.

 

Watching Coot-Looting Wigeons at Buttertubs Marsh

I sometimes wonder why I don’t get bored going to the same birding locations month after month, year after year.  A big part of it is that, on any given day, there is a chance that they will see something different or rare or perhaps even totally new.

This past Sunday, while on an organized outing with a bunch of local birders to Buttertubs Marsh Bird Sanctuary in Nanaimo, I got my “something-new” fix.  In this case is wasn’t a new species of bird — instead it was an inter-species interaction that I had never noticed before – that of an American Wigeon stealing food from an American Coot.

Scene 1: Following the Coot

Coot (Fulica americana) & American Wigeon (Anas americana)

The first of the two species, the American Wigeon (Anas americana), is a duck that is part of the genus Anas sometimes referred to as dabbling ducks.  These duck may feed on land or on the water where they can tip themselves upside down and gather underwater plants up to several inches below the surface.

The second of the two species, the American Coot (Fulica americana), is in the family Rallidae of rails and looks a little like a small black chicken.  These birds may feed on land, by dabbling in shallow water or by diving for plants.

I captured a short video of the food stealing behaviour (kleptoparasitism) with my Panasonic DMC FZ-200 camera.  I may have had too much fun and gotten a little carried away with the presentation.  You be the judge:

At one point there were at least 3 or 4 Wigeon-Coot pairs doing similar food-stealing dances.

On another occasion I watched as a Wigeon tried to manage two Coots at the same time and seemed to spend a lot of time in the middle trying to decide which way to go.  Not a good strategy for a low-intelligence bird it would seem.

Some further comments and other notes resulting from forays into online ‘research’:

  • A 1979 article suggested that the Wigeon is the only duck known to be a regular kleptoparasite (ref [3]).
  • A 1984 article documents Gadwalls stealing food from American Coots (ref [4]).
  • Other ‘dabbling ducks’ in the genus Anas include the Mallard, Wigeons, Teals, Shovelers, Pintails, the Black Duck, the Gadwall and a few others.
  • Wigeons apparently will try to steal food from other diving water birds, not just from coots.
  • Coots, in turn, have been known to steal food from other water birds.
  • Coots will also dive to escape predators (the Coot is one of the easiest birds for the Bald Eagle to catch).

References

A good source of information that I like to use is the Birds of North America online service from the Cornell Lab of Ornithology.  The service is not free but for anyone curious about bird behaviour it’s worth the price in my opinion.  They have a one month subscription that costs $5 if you want to give it a try.

[1] BNA online article on the American Wigeon.

[2] BNA online article on the American Coot.

[3] H. Jane Brockmann & C. J. Barnard,  Kleptoparasitism in birds, Animal Behaviour Research Group, Department of Zoology, University of Oxford, UK
Animal Behaviour (Impact Factor: 3.14). 05/1979; 27:487-514. DOI: 10.1016/0003-3472(79)90185-4

[4] Juan A. Amat & Ramón C. Soriguer, Kleptoparasitism of Coots by Gadwalls, Ornis Scandinavica 15: 188-194.  Copenhagen 1984.