June 30, 2012:
White-winged Dove Range Map*
Enlarge
The Northward Expansion of the White-winged Dove in New Mexico along the Río Grande.
The White-winged Dove (Zenaida asiatica) was observed on the Dixon CBC for the first time in 2010. It appeared again in the 2011 count.
The table below shows historical data from New Mexico Christmas Bird Counts along the Río Grande Valley. These changing northern limits of the year-round range are
shown on the map at the right.
If you consult range maps in various field guides, you will find a great variation in the described breeding and wintering ranges. This is clearly a result of the rapidly changing
distribution of the species. Range maps created before 1980 will show the year-round range reaching only about 50 miles into southern New Mexico (Just north of Las Cruces), with the breeding range extending another 10-20 miles
north. Most maps produced closer to the turn of the century still show the year-round range barely reaching into New Mexico, but show the breeding range reaching as far north as Albuquerque.
This is the case for the original Sibley's published in 2000. However, when Sibley published his guide to the western birds in 2003, the range map had been
updated to show the year-round and breeding ranges in Río Grande Valley to be identical.
When the Las Cruces CBC was begun in 1975, small numbers of wintering
White-winged Doves were observed. As you can see in the data, by the 1990s many birds were over-wintering and by 2000 the year-round population had exploded into the tens of thousands.
The further expansion north is clearly shown in the data. Though the Albuquerque and Santa Fe counts have been active since the early 1960s, the first wintering White-wingeds were not recorded in
Albuquerque until 1994 and in Santa Fe until 1998. As you can see, the first records in the Española CBC were in 2005. The Espanola count has been active since the 1950s.
There is a new Peterson's guide out now with recently updated range maps. The new map shows the Rio Grande valley year-round and breeding ranges as being the same and reaching as far north as Santa Fe.
Additionally it shows a major northward expansion of the breeding range on the east side of the Rocky Mountains into southern Colorado with the year-round range on the plains reaching as far
north as Clovis, NM.
What we appear to be witnessing is a range expansion being led first by migrants into new territory, followed by some over-wintering groups forming year-round breeding populations.
In general, we know that the migration of birds is driven primarily
by food. If there are changes in the distribution and/or migratory patterns of a species, it is likely that there are changes in food availability in the areas involved.
If this is the case here, might it
be related to
changes in agricultural activity? Might climatic changes be involved as well?
Source of data: National Audubon Society (2010). The Christmas Bird Count Historical Results [Online]. Available http://www.christmasbirdcount.org [January 2011]
|