Good-bye Winter

Spring Already?
February 12, 2017

I started the day at Mesilla Park in Las Cruces vaguely hoping to relocate the duo of Turkey Vultures that had turned up unseasonably early the day before. I was unsuccessful but I feel it is worth a dialogue nonetheless.
The following are screenshots of eBird reports of Turkey Vulture (Cathartes aura) centered around Dona Ana county, New Mexico from December to February (winter records). The first screenshot captures reports from the winters of 1900 to 2015. The second represents the winter of 2015-2016. The third is the winter of 2016-present. Keeping in mind of course that February 2017 is only halfway over. Click on the images to enlarge them.

1900-2015 winter TUVU eBird records

2015-2016 winter TUVU eBird records

2017 winter TUVU eBird records

 One notable pattern is that most records occur in generally the same locations. Mesilla Park (the location of the red 2017 hotspot pin and the blue pin in subsequent years that lies almost in the center of Las Cruces) has a well established Turkey Vulture roost in the warmer months (a period of time that is apparently increasing in length every year). It is also fairly regularly visited by birders. There have been two reports of Turkey Vultures from this location this winter, both of which were substantiated with photos. The first was in from January 12, 2017 (single bird) and the more recent sighting was of two birds on February 11, 2017. It is worth noting that an increase in the number of competent eBird users also has an impact on the number of reports.
Undoubtedly an indication of things to come, it seems likely that Turkey Vultures are following the mild weather upward in both latitude and elevation. Wintering Turkey Vultures in much of California and the Eastern US are not necessarily exciting, but the increase in records at higher elevations is what is telling. Even within New Mexico there are a few small populations of sporadically wintering Turkey Vultures in the eastern portion of the state, but these areas are still generally lower in elevation than Las Cruces. This year's recent record is a full 10-14 days earlier than most early arrival dates for Las Cruces. On one hand this is seems to be a clear result of a changing climate. On the other, it is a testament to the flexibility and adaptability of these birds. By taking advantage of suitable conditions further north, these Turkey Vultures can reduce both interspecific and intraspecific competition on their wintering grounds. Further south these individuals would need to compete with lots of other Turkey Vultures, as well as Black Vultures (Coragyps atratus) for carrion. The problem comes when colder temperatures once again return (as they are projected to do in Las Cruces over the next week). Not only does the cold stress the birds themselves, but it also decreases the rate at which carrion decomposes. This could potentially impact the vultures' ability to detect food. For now it will fall upon a few hardy and adventurous immigrants to winter further northward than usual. Eventually I fully expect there to be a sizable wintering population of Turkey Vultures in the Las Cruces area (and perhaps beyond) within the next decade. At this point its very hard to tell what changes are going to take place with this increasingly chaotic and unpredictable climate we are faced with. This is especially true with bird populations, though likely, southern species will continue to move north, as these Turkey Vultures are apparently doing.

Temperature reading (approx. 31 C) from the afternoon of Feb. 10th near Ft Hancock TX. Its no wonder TUVU are bumping northward and upward in elevation!

Other notable species for the day included an Eastern Phoebe hanging around the garden area of Mesilla Valley Bosque SP and a quartet of Tree Swallows feeding amid the stormy weather and wind at Leasburg Dam SP.

Eastern Phoebe (Sayornis phoebe) MVBSP Feb. 12, 2017

Tree Swallow (Tachycineta bicolor) Leasburg Dam SP Feb. 12, 2017

I then spent the rest of the day at Sunland Racetrack in El Paso hoping to relocate the previously reported Hooded Mergansers (Lophodytes cucullatus) (a species I still have not observed in Dona Ana county, NM). I was unable to find the mergansers, but there were two Eared Grebes (Podiceps nigricollis) on the pond. The extreme winds caused the entire surface of the large pond to froth with white-caps, and the hundred of gulls (99% Ring-billed with a handful of Herring and California) present hunkered down on the water in the middle of the pond. It was not a pleasant stakeout, but on my way back I was able to explore the Santa Theresa area which has staged several historic vagrants for NM but recently seems to go under checked by birders.
The search for Vultures and the sight of swallows certainly made it feel like spring (as did the mild 60 degree weather and horrendous wind). Juxtapose this with lots of lingering waterfowl and gulls and it certainly feels like odd things are afoot climatologically speaking.
Hopefully the doldrums period of late February and early March is brief!