That's when I heard the tell-tale sound of whistling wings overhead.

"Ducks!" I said. "Stay still."

Ryan's eyes were as big as saucers as the flock of 30 ducks or so circled the pond once, then set their wings and began rocking from side to side as they glided in to make a landing.

"That was cool," Ryan said in a hushed voice as the ducks swam among the goose decoys.

Cool indeed.

The first leg of the 2005 duck season opens Saturday in Pennsylvania's South Zone, which includes Lancaster County, and runs through Oct. 15.

Unfortunately for local duck hunters, the summer drought could make finding ducks a bit of a challenge this year.

On Sept. 29, the Susquehanna River was just 3 feet deep at the Harrisburg monitoring gauge. That's as low as it's been in three years.

John Dunn, the Game Commisison's chief waterfowl biologist, said low-water conditions across the state this summer have taken their toll on Pennsylvania ducks.

"The current drought appears to be affecting the distribution and possibly production of young," Dunn said. "We had average spring breeding populations and good water in wetlands at that time, but things quickly dried out and may have impacted brood rearing conditions for ducks."

The drought even had an impact on duck research in the state this year.

"Our statewide banding totals were off at least 40 percent from last year as many of the wetlands we trap were dry or had very little water," Dunn said.

Ever the optimist, however, Dunn said the outlook for the coming season is not all bad.

"On the plus side, there appears to be a lot of natural duck food available so if we get any water before the season starts we could hold a lot of migrants," he said. "Low water can make finding ducks difficult, but if you can find water and food you can have a very successful hunt."

All duck population estimates from the spring 2005 statewide survey were statistically similar to the 10-year average.

The number of mallard pairs was estimated at 95,685, compared with the average of 99,814 pairs.

The southeastern and southwestern parts of Pennsylvania had the highest densities of breeding mallards.

The trend in mallard pairs, according to Dunn, has been stable since liberal hunting seasons were initiated in 1995.

There were no black ducks observed in the state on survey plots for the second consecutive year and only the third time in 16 years.

Black ducks have been observed at very low densities since the survey was initiated in 1989. However, numbers of black ducks banded in Pennsylvania during August and September have also been declining in recent years.

Breeding black ducks in Pennsylvania are increasingly rare, which Dunn says is cause for concern.

There were 60,536 wood duck breeding pairs estimated during the 2005 survey compared to the average of 49,137 pairs. Wood duck densities were highest in northwestern and southwestern Pennsylvania. Estimates of total blue-winged teal (2,746) were down 68 percent from the annual average, while total green-winged teal numbers (7,089) were 60 percent higher than average.

It should be noted, Dunn said, that an unknown number of migrating teal are counted on this survey each year and may lead to wide fluctuations in estimates not related to breeding populations.

In looking at duck populations on a regional basis, mallard breeding pair estimates for the northeastern United States declined by 7 percent from 2004. Wood duck pairs increased 13 percent from 2004 and the black duck estimate declined by 14 percent.

Last year, Pennsylvania licensed about 23,500 duck hunters. That's down 27 percent from 2003.

Those hunters who did get out last year enjoyed a banner season. Pennsylvania's estimated total duck harvest of 138,000 birds was up 11 percent from 2003.

Of the total number of ducks put in the bag, biologists estimate 71,600 were mallards, which is 19 percent more than hunters took in 2003; 27,700 were wood ducks, which is similar to 2003; 5,600 were black ducks, which is down 20 percent; and 5,000 were green-winged teal, which is down 30 percent.

So just what is the problem with Pennsylvania's black duck population?

Researchers in Penn State's College of Agricultural Sciences have found that the growing scarcity of black ducks is not due to habitat problems in northern nesting grounds, but rather to them successfully breeding -- with mallards.

"Until relatively recently, black ducks were an isolated offshoot of the much larger mallard population. Since 1940 or so, hybridization of black ducks and mallards has resulted in fewer black ducks," said Margaret Brittingham, professor of wildlife resources, who conducted the study along with Judith Mank and John Carlson from the School of Forest Resources at Penn State.

Some scientists argue that black ducks were never a true species, but rather a color morph or subspecies of the mallard population.

However, by looking at museum specimens of black ducks and mallards collected before mallards were common in the East and comparing them with modern specimens, the researchers could determine if mallards and black ducks were always genetically very similar or whether this similarity had occurred recently.

The Penn State scientists conducted DNA tests on 135 duck wings obtained from the Atlantic Flyway parts count done by the U.S. Fish & Wildlife Service. The wings, collected from hunters from Maine to South Carolina, came from 45 mallards, 42 black ducks and 48 hybrids. To examine DNA from ducks taken before 1940, researchers collected feathers from museum specimens.

"What we found from DNA testing was that historically mallards and black ducks were very different genetically, and they have become much more similar in recent decades due to hybridization," said Brittingham. "Because the mallard population is so much bigger to begin with, the effect is greatest on the black-duck population. In looking at the DNA of modern specimens, black ducks are no longer very distinct from mallards, and we are losing the unique species known as the black duck.

"We believe that's why we are seeing fewer of them, and we are concerned that without preventing hybridization, conservation of black duck habitat will not be sufficient to preserve this species."