Amateur Naturalist: What Is Happening To The Birds? 2

Submitted by Carol A. Clark
on February 16, 2019
- 2:09 pm

The evening grosbeak, beneficiary of changes in the habitats of Los Alamos. Photo by Bob Walker

Amateur Naturalist: What is Happening to the Birds?

By ROBERT DRYJA

Los Alamos County can be categorized as having 12 kinds of habitats for birds.

Five of these habitats are defined by the dominant species of trees growing in them. These vary from piñon/juniper to spruce/fir trees. The piñon/juniper habitat is at lower elevations toward the Rio Grande. The spruce/fir habitat is at the highest elevations toward the mountain tops. There is a mile change in elevation when going from the Rio Grande to the mountain tops.

The other six habitats have special characteristics. These include being marshes, cliffs or the Rio Grande gorge. Bird watchers have provided data to the Cornell Feederwatch program since 1989. They have seen sixty-one species over the years that are associated with 11 of the 12 habitats.

CHART A shows that about 200 to 550 birds were seen annually in the earlier years from 1989 to 2006. The number then increased to about 1,100 annually in more recent years. These is one distinctive peak for 2012 when about 1,500 birds were seen for the year. The statistical dotted line shows a trend in which the counts have increased from about 300 to 1200 annually, or a fourfold increase.

The impression is that birds are prospering despite concerns about climate change, droughts and two major forest fires. Indeed, the peak for 2012 occurs in the year after the Las Conchas fire. (The red line segments in CHART A identify the year after the Cerro Grande and Las Conchas fires.) Did the fire aftermaths actually create habitats that were helpful to birds rather than a detriment?

CHART A shows the overall pattern for all species and all habitats combined. However, what has been happening in specific habitats and for individual bird species? The situation actually is like a joke from statistics. On the average you feel fine when you have your foot in a bucket of ice water and your hand on the stove. Specific species typically associate with specific kinds of habitats when breeding. Mallards associate with marshes and ponds for example. However, there are some species that are associated with all habitats when breeding. Bird watchers have reported seven species that are associated with all habitats.

Chart B shows the annual counts for these seven species. The trend line shown in CHART B is similar to CHART A. The counts remain relatively low until 2009 and then peaks in 2014. The dotted statistical line shows a similar upward trend in the annual counts.

However, what happens when individual species is considered? The count for each of the seven species varies dramatically for the twenty-nine years as shown in TABLE A. The evening grosbeak accounts for nearly two-thirds of the total count.

TABLE A

Count of Species Associated with All 11 Habitats:

Broad-tailed hummingbird ― 4
Chipping sparrow ― 58
Western bluebird ― 81
Northern flicker ― 149
Common raven ― 226
American robin ― 501
Evening grosbeak ― 1,694
Total ― 2,714

CHART C shows a different trend when the evening grosbeak is excluded. Two peaks occur in 2007 and 2012 for the six species. The dotted line is a slowly rising curve that becomes nearly level from 2002 to the present. About 40 to 45 birds are seen annually after starting at about 10 birds in 1989. It appears that the evening grosbeak has been the major beneficiary of the changes resulting from the forest fires, draughts, and climate change while the other six species may be benefiting only somewhat.

CHART D show three more variations in annual counts for individual species when compared to the group counts in CHART A. The chipping sparrow and western bluebird are rarely seen from year to year. However, three annual irruptions occur when 20 to 25 are seen. The northern flicker in contrast slowly increases in its annual count until 2008 when 12 are seen and it then begins to decline. The combined annual pattern for the seven species (the feel fine average) is not matched when individual species are considered (the hot stove or cold water).