An Exceptional Set of Eggs of the Wood Duck.
ONE of the prettiest spots in San Joaquin County is located in the extreme north-west portion of the county and is known as "Forest Lake." Previous to last year I had never visited the lake and as the name seemed to suggest a likely place for birds, I inquired of the farmers living in the vicinity as to the prospects of finding ducks breeding there and was informed by all that this was a favorite haunt of the Wood Duck. (Aix sponsa.)
I therefore determined on a trip to the place and April 29, 1900, in company with my brother and a friend, we started from Lodi on our wheels about 5.30 A.M. and reached the lake about 8.30 A.M. Dismounting we immediately strapped on our baskets, arranged the other necessary collecting apparatus and started along the north side of the lake, keeping a sharp lookout for any suggestion of a nest.
We had not proceeded far before a male Wood Duck arose from the water's edge and beat a hasty retreat. Thinking that his nest might be in the vicinity we began a thorough search and were soon rewarded by finding the nest located in a deserted home of a Redshafted Flicker and placed about twenty-five feet up in a white oak tree. The tree was quite large but after a difficult climb my brother reached the opening and inserting his hand drew the female bird from the nest. He informed ts that the nest was full of eggs, which fact was made very evident after he had taken out twenty-one eggs and landed them safely on terra firma.
The number of eggs in the set led me to believe that the nest was occupied by two pairs of birds, but after a thorough search of the lake I failed to find but one pair, notwithstanding the fact that I had been informed that the birds were quite uumerous in the locality. However I was well pleased with my prize and after taking several sets of Swainson's Hawk (Buleo swainsoni) started homeward.
I now have the eggs before me and my belief in the double occupancy of the nest is made stronger by the fact that nine of the twenty-one eggs are somewhat darker in color than the remaining twelve and are also, as a whole, slightly larger, as the following measurements will show
- 2.06 x 1.50
- 2.12 x 1.50
- 1.93 x 1.56
- 1.93 x 1.50
- 1.93 x 1.50
- 1.93 x 1.50
- 2.06 x 1.50
- 2.03 x 1.47
- 2.00 x 1.56
- 2.00 x 1.56
- 1.87 x 1.43
- 1.93 x 1.47
- 2.00 x 1.50
- 1.93 x 1.47
- 2.00 x 1.47
- 2.00 x 1.50
- 1.93 x 1.50
- 2.00 x 1.50
- 1.93 x 1.50
- 1.93 x 1.47
- 1.93 x 1.43
Taken in their order, the first nine measurements are those of the dark colored eggs while the remaining twelve are of the light color.
Incubation had already commenced in four of the dark colored eggs and in six of the light color, thus showing that they must have been laid by the same bird or by two birds occupying the nest at the same time. Had incubation been more advanced in one color than in the other, I would have been led to believe that the pair of birds found in possession of the nest must have driven the first pair away and continued adding to the number of eggs already in the nest, but the state of incubation in the two colors has shown that such could not be the case.
After considering all the points in favor of the theory of two pair of birds occupying the nest at the same time, it seems to me that they are stronger than those in favor of one pair of birds, as the best point for the latter theory is the lack of another pair of birds in the vicinity, while the number of eggs in the set and the difference in color and size are certainly good points in favor of the former.
This is the first instance I have had brought to my notice of a decided difference in color and size of a large set of eggs of the Wood Duck and may only be in this case a freak set. However I would like to hear further notes on this subject from other members of the Cooper Club.
Stockton, Cal. WALTER B. SAMPSON.
