The Dec. 17, 2020 Patagonia Christmas Bird Count left some concern about the reduction of bird numbers compared to past bird counts. Specifically, the consensus from volunteers who participated is that the sparrow count was significantly down from past years with the exception of the white-crowned sparrow at a record 667 individuals. No new-world sparrows were observed in the western portion of the count area in San Rafael Valley.
Bird populations have declined by more than a third since the 1970s. Grassland-dwelling birds, including sparrows and meadowlarks, are especially vulnerable and, in some species, have lost much more than a third of their populations.
The most likely reason for these dangerous declines, according to the Scientific American article ”Silent Skies: Billions of North American Birds Have Vanished,” by Jim Daley, Sept. 19, 2019, is due to the fact that “intensification of agriculture is happening all over the world, [as is] increased use of pesticides, as well as the continued conversion of the remaining grass and pastureland – and even native prairie” to cropland.
Since Christmas Day, 1900, the National Audubon Society Christmas Bird count has been collecting data on bird populations and species which provides valuable information worldwide on population trends of birds. Knowledge of bird species and population trends provides valuable information about the health of the environment.
The Patagonia Count, started in 1963, takes place in 7.5-mile radius circle with the center near the intersection of Harshaw Creek Road, Harshaw Road, and the San Rafael Valley. Once established, the designated count area remains the same every year for accuracy of bird population trends.
This year in the western area of the count circle, in San Rafael Valley, only a few house sparrows were found near a ranch house. House sparrows are an old-world species that were introduced from Europe into New York City in 1851 and arrived in Tucson by 1903. The remaining sparrows that are found in southeastern Arizona are considered new-world sparrows indigenous to this area.
There are 23 species of sparrows who are naturally occurring in southeastern Arizona. Of these 23, the historical data of the Patagonia count shows that 16 of these sparrow species have been identified during the past Christmas Bird Counts.
Data available from 2014 through 2020 shows that, overall, the species counts and individual counts have remained consistent. Species counts range from a low of 131 in 2014 to a high of 142 in 2017. Individual numbers of birds during these years also remains consistent with a low of 5,291 in 2019 and a high of 6,482 in 2015.
The recent count was alarming in that some species regularly counted in abundant numbers have dropped. For example, the chipping sparrow has fallen from a high of 875 individuals in 2014 to 199 individuals in 2020. This seems alarming, although their conservation status in North America shows the population of chipping sparrows as common and widespread.
The lark sparrow generally had numbers from 50 to 100 from 2014 to 2017, but dropped to only seven individuals in 2020. In recent decades populations of lark sparrows have disappeared completely from former nesting grounds east of the Mississippi but is still common and widespread in the West according to National Audubon.
One likely explanation for the lower counts in the survey is the prolonged drought and lack of grass for forage, especially in the western area of San Rafael Valley. Most passerine birds counted in that area were at one small water source.
In summary, the species of sparrows historically counted during the Christmas Bird count were not significantly lower than past count trends, other than the lark and chipping sparrow. Interestingly, almost all the grassland sparrow species counted, other than the lark and chipping, have population declines in their normal habitat throughout North America. Declines in population are attributed to habitat loss due to grazing and farming. Tracking population trends requires decades of data, so a few years of declines or increases does not confirm a problem but does raise a red flag for further observation and conservation awareness