Catoctin Winter Bird Count

What they are and what they tell us about bird populations,
distributions, and the effects of climate change

David Smith
Frederick Bird Club & Audubon Society of Central Maryland

(2/24) Folks interested in birds have many ways to express that interest these days, with access to vast sources of information at our fingertips. Some folks are casual observers or photographers of birds; others like attracting birds to their yards with food, water, or shelter; while more hard core bird enthusiasts or "birders" as they are called participate in more active bird watching pursuits. These can include trips to nearby or distant areas to look for birds or it can include participation in various seasonal bird counts.

In Maryland, birders have two statewide organizations whose focus is birds. The National Audubon Society (NAS), which has been around for more than a century, is focused primarily on bird conservation and advocacy. There are five active chapters of NAS in Maryland in the District of Columbia, plus a statewide organization. The local chapter is the Audubon Society of Central Maryland, which includes all of Frederick County and portions of Carroll, Howard, and Montgomery counties.

The chapter supports two 100+ acre sanctuaries in eastern Frederick County with seasonal fundraisers, including birdseed sales and a native plant sale. The chapter board meets irregularly to conduct business. The Maryland Ornithological Society or MOS, which was first started in 1945, seeks to promote the study and enjoyment of birds. Many chapters of the MOS occur primarily at the county level. In Frederick County, the Frederick Bird Club is the active local chapter of the MOS. The club meets the first Thursday of each month at 7 p.m. between September and May for talks on birds and other areas of natural history. In addition to meetings, there are bird walks and the aforementioned seasonal bird counts.

This time of year finds Frederick County "birders" involved in several types of winter bird counts. The first of these is the Audubon Christmas Bird Count run by the NAS for well over 100 years. Prior to 1900, many Americans participated in what was referred to as the Christmas "Side Hunt." Teams would go into the field, rifles in tow, and whoever brought in the most birds and mammals won the event. Around the turn of the twentieth century, the appreciation, rather than the exploitation, of nature was beginning to gain popularity, and many people began to question the practice of the holiday "Side Hunt." In 1900, Frank M. Chapman, an ornithologist at the American Museum of Natural History in New York and an early officer in the newly formed NAS, proposed a new practice designed to count the numbers of birds over the holidays rather than shoot them. This practice, referred to as the "Christmas Bird Census," spread throughout the country and soon replaced the hunt with a tally of all birds in winter.

The census, now known as the Christmas Bird Count, has continued since 1900, and is now conducted throughout the Western Hemisphere, though the vast majority of counts occur within North America. Counts are a single day tally of the numbers of individuals of all species of birds from within a circular area with a 15-mile diameter. They can be run on any day between December 14 and January 5, but must first be registered with Audubon and specific protocols followed, before the data will be accepted. Information about the count, including count data, can now be viewed electronically by visiting the Audubon Christmas Bird Count website at: www.audubon.org/conservation/science/christmas-bird-count.

The 2019 count next December will mark the 120th season of the Christmas Bird Count. Folks living right here in Northern Frederick County may not realize that a Christmas Bird Count has occurred in their backyard so to speak for over 60 years! The Catoctin Mountain Christmas Bird Count was started in 1950 by John Richards, a professor of Physics at The Mount. Centered just outside of Thurmont, Maryland, the count includes much of Northern Frederick County and a small piece of southern Adams County, Pennsylvania and western Carroll County.

The 66th Catoctin Mountain Christmas Count was held on Sunday, December 16, 2018. Considerable rain had fallen in the previous days causing the larger rivers to flood their banks, making driving and birding in some areas a challenge. Even so, the current count compiler, Kathy Brown, reports that 63 species of birds were found on the day, slightly higher than the previous year. Kathy reports that this total included species not seen every year, such as Lapland longspur, rusty blackbird, purple finch, and eastern phoebe.

While the Christmas Bird Count has occurred in early winter since its beginnings, many birders over the years noticed that some birds are still migrating in early winter, having not yet reached their true wintering grounds. For this reason, many states have adopted additional counts later in winter when all but the most nomadic of bird species are finally settled in for the winter. In this way, the count would reflect true winter bird distributions. In Maryland, these midwinter bird counts were begun in the mid 1980s. Counts are done on a countywide basis on a given day generally between mid January and early February.

The Frederick Bird Club did not have a midwinter bird count until 1995 when I organized the first count. I have served as the county count coordinator ever since. The 2019 Frederick County Midwinter Bird Count was the 25th consecutive midwinter count. We had a team of over 30 people that spread out throughout Frederick County to count all birds within the fields, forests, rivers, ponds, and cities and towns. It was a cold day, but dry and calm. Most still water was frozen, but the rivers and creeks were flowing. We managed to find nearly 30,000 individuals of 88 species, including one species, American Woodcock, which had not been previously reported during the first 24 years of the count. The woodcock, an upland shorebird with short legs, a long stout beak, and an odd aerial courtship display, was the 135th species of bird observed on the count.

Over the years, we have seen some truly amazing species of birds. Most are the usual species that are either year round residents or regular winter residents. However, in some years we have had species that are considered irruptive, meaning that they do not normally stray this far south in winter, but because of failed food resources farther north, they must go farther afield to survive. These have included snowy owl, crossbills, redpolls, and northern shrike. Other oddities have arrived after being blown way off course during their migrations, including a northern lapwing from Europe, a white-winged dove from down south, and a rufous hummingbird from out west. Still other species are unusual because they normally leave our area before winter sets in, but may remain in our area in some years. These have included brown thrasher, gray catbird, common yellowthroat, and chipping sparrow. A brown thrasher was present during this year’s count, only the sixth time it has been recorded in 25 years.

One very noteworthy thing about both the recent Catoctin Christmas Count and Frederick County Midwinter Count is that the numbers of Carolina chickadees and tufted titmice were at historic lows. For the midwinter count, the tufted titmouse numbers were 64% below the previous 24 year average. The Carolina chickadee numbers were even more dismal, with a 71% drop over the 24 year average. Both of these species are considered quite common throughout the state so why did we see such an unprecedented decline over the preceding year? Some have speculated that it has to do with one of the worst nesting seasons in history during 2018.

So why do we intrepid birders leave the warmth of our homes and risk frostbite every year to count birds in winter? The answer is to better understand how bird populations and distributions are doing over time and to see how these have changed with changes in land use and climate. Long term data sets, such as the Audubon Christmas Bird Count and MOS midwinter counts, are ideal for showing these changes. One example is the chickadee and titmouse declines observed this year. Another example observed over a longer time frame is of a formerly common wintering sparrow in our area, the American tree sparrow.

This species has been declining in the Piedmont region by -4.63% per year over the past several decades. At the other extreme, the black vulture, one of two primarily scavenging birds of prey species in our area, has been increasing by 6.73% per year over that same time. This species was not even observed on the Catoctin Christmas Count until 1976, but is now seen every year and in increasing numbers. What becomes apparent from looking more deeply into the Christmas count data is that with average temperatures generally increasing over the past several decades, a species like the American tree sparrow is no longer migrating as far south in winter as it once did. This species breeds near the tree line in far northern Canada and Alaska and generally winters across most of the northern US south to North Carolina and Tennessee in the east. However, the greatest increase in the percentage of wintering American tree sparrows (3.66% per year) is for birds in the boreal taiga plains of north central Canada, suggesting that these birds may be remaining farther north rather than migrating to our area.

Sadly, these winter counts have also noted the extirpation of some of our former bird species, such as the northern bobwhite. This smallest eastern chicken-like species was once a common sight in the rural farmland of Frederick County. However, with changes in farming practices in the 1960s and 1970s, including the removal of hedgerows between fields, these birds no longer are found in the county or even within the region. They have never been recorded on the Frederick Midwinter Count and the last bobwhite was observed on the Catoctin Christmas Count in 1983.

So I hope you now have at least an appreciation for those of us who brave the elements each winter to document the birds that call our neighborhood home. While it can sometimes be an uncomfortable day in the field, it is nevertheless interesting to see what species are still within the various patches of habitat within the count circle or county. And knowing that the data help to explain observed changes in winter distribution or population sizes and may someday help to guide conservation practices, makes it all the more rewarding. If you are interested in knowing more about the birds in Frederick County, consider joining the Frederick Bird Club or Audubon Society of Central Maryland. You can find out more about the Frederick Bird Club, and the MOS as well, by visiting the chapter website located at www.frederickbirdclub.org. You can find out more about the Audubon Society of Central Maryland and Audubon Maryland/DC by visiting the website at www.centralmdaudubon.org.