By Paul Dye and Arnold Schouten

A unique opportunity presented itself early in 1998 in Washington State; private aviculturists working with professional wildlife biologists and a University for a better understanding of Harlequin ducks. This effort was a logical extension of a study already in progress for a couple of years by university and Department of Fish & Wildlife personnel.

Four Adult and Four Juvenile Harlequins

Harlequin ducks can be seriously affected by degradation of water quality and encroachment of human development in breeding streams. Because they gather in coastal waters and depend on intertidal habitats close to shore they are particularly vulnerable to oil spills. Harlequins have relatively low productivity and lead precarious lives in remote river valleys and along secluded coastlines. A need existed for Immediate studies of their breeding productivity. A great deal needs to be learned about this small sea duck to better understand its ecology and ensure its conservation.

The ability to accurately determine the age and sex composition of wildlife populations is an important tool for wildlife resource managers. Information concerning the age and sex structure of a specific wildlife population is useful for identifying population trends. The age at which Harlequin ducks reach sexual maturity and attain adult plumage has not been proven. No formal studies with known age birds have been accomplished nor have plumage patterns coincidental with age been well defined for spring birds.

It was a natural extension of the field work already underway by the University and wildlife personnel to collect small numbers of harlequin eggs from nests located in and near their study area, in an effort to establish a captive study flock of known age Harlequins. These known age birds could then be used to determine age specific plumage characteristics and development and age at sexual maturity based on progression of bursa involution and blood hormone levels. Additional valuable wildlife management data would be gained by cataloging nest site selections and measuring nest distances from the river, both vertically and horizontally. A side benefit for aviculture would be the opportunity of working and studying side-by-side with wildlife professionals, with the possible result of developing reliable techniques for breeding Harlequin ducks in captivity. When we first learned of the possibility of this opportunity we felt it was a dream come true, as we both enjoy the challenge of working with difficult species.

During a presentation regarding his Harlequin research in Prince William Sound at the 1995 IWWA conference in Seattle, Dan Rosenberg of Alaska Fish & Game stated that photo recording of plumage development in known age captive Harloquins would provide a useful tool for Harlequin researchers. Unfortunately, the current population of Harlequins in captivity is small and widely scattered, with only limited reproduction. As a result, the photographic data that could prove useful is currently unavailable. Our research should provide this photographic data, as well as describe via bursa and hormonal measurements, the age at which sexual maturity is attained for this research group.

For those unfamiliar with the bursa, it is a cul-de-sac like dorsal diverticulum of the cloaca, and is involved in the production of antibodies of developing chicks and ducklings. It is visible by manually exposing the cloaca, as in vent sexing. In chickens, it grows rapidly the first three weeks after hatching, and plateaus until the eighth week when it begins to regress. Involution (shrinking) of the bursa may be influenced by elevated levels of sex steroid at least in males, as evidenced by the fact that caponization enhances growth of the bursa, while elevated levels of testosterone decrease its growth. Research conducted on Ring Necked ducks, Canada Geese and Oldsquaw (Longtails) generally supports the hypothesis that the bursa completes involution and closes at sexual maturity.

The progression of bursa involution will be related to circulating levels of sex steroid hormones and body growth in the Harlequins. 150 micro liters of blood will be collected into microcapillary tubes within 3 minutes of catching each bird. Basal circulating levels of corticosterone, testosterone, estrodiol, and 5-alpha-dihydrotestosterone will be measured by radioimmunoassay technique by personnel at the University of Washington. Because Harlequins delay reproduction until after the first spring, and because of their close phylogenic relationship to the Oldsquaw, we expect to find bursa involution and elevated hormonal levels sometime after the first spring. From the findings of other studies one would expect bursa involution to also be related to initiation of breeding in female Harlequins. If the involution progression is fairly linear, bursa depth may further distinguish second from third year individuals. Once the validity of this technique has been tested using these known age birds, it can be incorporated in the management of wild Harlequin populations.

We made approximately 30 study and collecting trips to 5 Olympic Peninsula rivers during 1998 and 1999. It turns out that our original assumption that we would find enough nests to satisfy our needs simply by devoting days to searching islands and along river banks was naive. In 1998, in spite of many days of rigerous searching, we found only one nest. One of the problems is that the hens often tend to sneak off the nest well in advance of your approach, giving no indication of the nests location. Much of the searching was done in nearly vertical terrain in a rain forest setting, with vegetation so thick you could barely make your way through it. Late that spring, to our chagrin, we resigned ourselves to the fact that we'd probably have to settle for capturing ducklngs, also allowed per our permit, rather than collecting eggs. We were dissapointed, as we felt that birds raised from eggs were more likely to nest in a captive situation than those live-trapped as ducklings.

Unfortunately, 1998 turned out to be a bad year for brood survival due to a high number of river otters, and not that many ducklings survived to a trapable age. We were reluctant to scatter broods less than a couple of weeks old, as the resulting chill was likely to take a heavy toll of the young. We concluded the 1998 rearing season with just 3 Harlequins in hand, one we reared from an egg and two we caught as ducklings. We knew we had to find a more productive method of locating nests for 1999, if our study was to be successful.

Back at the drawing boards we concluded that the only way we were likely to find the number of nests needed to satisfy our permit in 1999 would be to net females, install transmitters, and then using a hand-held receiver, track them back to their nests. We were not certain of the complexity of this method, as we were not familiar with the operatiom of the recievers involved. In many cases the receiver would only get us to the general proximity of a nest, and a lot of searching was still required.

Our first location of a pair of Harlequins that were good candidates for transmitter installation occured in early May 1999. We stopped to scan a river with our binoculars and immediately spotted a pair. Our excitement grew when we observed that the female was aggressively searching out nest sites. She repeatedly investigated cavities in a vertical cliff just a short way upstream from the rivers mouth. We moved a short way upstream and erected our net out of sight of the pair. It took a good deal of teamwork to maneuver the pair into position for the catch. Whenever possible we attempted to catch both members of a pair and band them both in addition to installing the transmitter on the female. In this case we found that this pair had already been banded and had been observed as mates in previous years. Immediatly upon capture the birds are placed in holding bags while the transmitter installation equipment is assembled. A hood made from a baby sock is placed over the females head to keep her quiet while we install the transmitter. A location just behind the neck is prepared for a small incision by removing a few feathers and disinfecting with alcohol. The transmitter mounting clip is inserted into this incision which is then closed with a drop of super glue. A drop of this same glue is applied to the bottom of the transmitter, which is then pressed against the skin below, giving a second attachment point and preventing the transmitter working loose during rigerous activity. This installation provides a secure mount, while having no long-term affect on the bird, as normal epidermal rejuvenation causes rejection within months.

Harlequin Female with Transmitter Installed

While we were installing this first transmitter we also monitored the net, just in case another pair of harlequins became entangled. To our amazement a hen mallard barrelling upstream at high speed ripped right through the net like it was'nt even there. Right behind her followed a beautiful mature Bald eagle in full persuit. Upon seeing the movement of the net from the mallard's encounter, the eagle was able to flare up and over the net, just evading it by inches. It was a marvelous wildlife drama to behold, and less than 50 feet away.

That was the first of 10 such transmitter installations we managed to successfully complete that spring, and although we caught several additional females we limited the transmitter installations to hens we determined were sexually mature using the bursa measurement technique.

One day, while hiking along one of the rivers looking for a pair to net, we accidentally flushed a female off her nest. It was an untypical site, even though it was located on an island surrounded by white water, in that it was located right out in the open under a small Grand Fir tree. She had 7 eggs, two of which we collected for artificial incubation and rearing.

With the help of a rugged portable receiver our nest search went well, and in spite of a few dissappointments we managed to collect the number of eggs allocated by our permit. The dissapointments included two hens captured in the lower part of their river, including the one from the "eagle incident", that appeared to abandon their nesting attempt after fitted with a transmitter. In both cases, these hens went back to the salt water and did not attempt to nest that year. Another hen, whose bursa measurement indicated that she might not as yet have reached sexual maturity, was tracked from an airplane to a location 9 miles from the nearest road. An all-day hike proved unproductive, and we concluded that she most likely was on a scouting expedition possibly for a nest site to use the following year. A report from the Canadian Wildlife Service indicated that she had been recaptured near Vancouver Island that fall, minus her transmitter, a good testimonial to our installation technique.

Another hen exhibited an advanced brood patch when captured for her transmitter installation. Had it not been so late in the day we would have left her alone for an hour after release and then returned to monitor her location. Instead we returned a few days later to find that her eggs had already hatched, and she had a brood of 5 ducklings on the river.

Over the years harlequins have proven to be much more difficult to breed in captivity than they are to rear. Unlike the similar Old Squaw (Longtail) duck, they begin eating quite readily. We started them on a diet of Mazuri Waterfowl Starter, a small extruded pellet with xx% protein. From 14 collected as eggs and 2 as ducklings during the 2 years we raised 11 that are still doing well as of this writing. As required by our permit, blood has been drawn from these birds for DNA identification, and to establish a baseline for future hormonal measurements. An additional benefit we received is that baseline DNA, bursa and hormonal data has been collected on the privately owned adult Harlequins we had in our possession prior to this scientific project. This allows us to accurately track their genetic heritage and their propensity for reproduction in the coming breeding season, prior to our study birds coming-of-age.

Bursa measurements taken on the young males in March 2000 have already provided some surprises to the biological community. It had previously been expected that the bursa of male and female Harlequins would involute at approximately the same age. At 10 months of age 5 of the 6 males are exibiting a significant reduction of bursa depth, while the females are not. This indicates that some of the aging data heretofore used in the field may have been erroneous, although more data needs to be assessed. We presented a paper to this effect at the Harlequin Working Group Symposium in Blaine Washington this spring.

Group of Young Harlequins in Breeding Enclosure

We each have somewhat different facilities that we feel  should be adequate to encourage breeding of these difficult birds. As a result of our collecting and rearing success we are both in the process of building additional facilities and could use advice from those readers who have previously experienced breeding success with this species. Options we are considering are potential benefits of isolating pair-bonded pairs to their own private quarters vs maintaining them as a small group to stimulate competition and more agressive courtship, possibly maintaining them in a group setting with other seaducks only during the off-breeding season. Heavily vegetated enclosures vs a more open environment is another consideration we must address, as well as the use of nest boxes, brush piles or cavities as potential nest sites.

As we stated at the beginning of this article, this effort began with a unique opportunity to use our avicultural abilities to contribute to an understanding of this beautiful species. So far it's turned into a marvelous adventure, rife with hard work, that we hope will benefit Harlequins, both in their wild habitats and in a captive environment.