Thermal image of rooftop nighthawk eggs (green ovals at the pointy end of the blue pencil) right after a female had left them. Not too bad at 98 degrees Farenheit.
I’m coming out as a climate scientist. There, I said it.
It seems absurd I have to say it, but that is the way of things these days. I study a bird that’s extremely heat tolerant, but even they have their limits. The mean maximum operative temperature (i.e. temperature experienced by the organism which incorporates wind effects) for Common Nighthawks in my study 2014-2016 was 132.8 degrees Fahrenheit. I can’t really avoid the topic.
So, I have to look at the trends in temperatures, wind, cloud cover, and rain over time for my region and decide at what threshold these extremely heat tolerant birds can no longer survive.
The prognosis? Mean temperatures in the Great Plains are expected to increase by 3.6°C to 6.1°C over the next 100 years (Preparing for a changing climate: the potential consequences of climate variability and change: central Great Plains. Colorado State University, 2002). For an excellent graphic that illustrates the temperature trends by global regions, check this out.
Sites where CONI satellite transmitters were deployed. Source: Elly Knight, WildResearch
Phew! Try to say that 10 times in a row! Common Nighthawks are given the CONI abbreviation in the American Ornithological Society bird checklists. Put that together with the concept of migratory connectivity and voila! You get CONIctivity!
Ahem. So, one question for many neotropic migrant (birds that migrate from the New World tropics) researchers: What is happening to these birds the rest of the year? For Common Nighthawks, this is important. In a previous post, I detailed the 9-month process that is the migration of this species. The Cornell Lab of Ornithology site, eBird, has done a very good job of tracking migration by species based upon birders’ data.
However, if we want real time data, by the bird from a specific region, that will require satellite transmitters, which I detailed in a previous post. The great thing about this technological development is that we are not required to recapture these birds to download data. Nighthawks are very difficult to capture. They do not passively fly through nets when going from point a to b, their vision is extremely advanced, they are mostly active at dusk and dawn, and they tend to fly high unless they are actively defending a territory.
So, a team of researchers across North America (see picture above) set out this summer to attach transmitters at a number of locations and luckily we had a few tricks up our sleeves to catch these wily birds.
For this study, we hope to answer some needling nighthawk questions. In particular, in some of these regions where they breed, nighthawks are increasing in numbers, and at others they are decreasing. Is this a function of where they breed or their migration path? We’ll find out in the coming year if the birds follow much the same path and timing, and where they stop and turn around.
Lady Sisyphus and a male who might be trying to persuade her to abandon her eggs and start a new clutch with him. She is not having it.
For nighthawks this was an unusual season. This year, only 14 of last year’s 22 breeding females returned to their rooftop. They could be at other rooftops, they might have died during the migration season, or they might be skipping the nesting season and just hanging around. This is my last field season in South Dakota, so I will never know.
Nighthawks returned 2-3 weeks later than last year, possibly due to the May Gulf of Mexico storms (that also wiped out some early nests on the Gulf).
On the flip side, June was a very mild month. So many of the chick and egg die-offs associated with high-wind thunderstorms and heat waves didn’t happen for the first brood this year.
And one lucky bird, whom I have named Lady Sisyphus (pictured above), finally hatched an egg, the first in five attempts. The chick died, sadly, but hey, that’s progress.
What do birds do during an eclipse? Much depends on the day cycle of the species. Is its diurnal, nocturnal or crepuscular?
As usual, Cornell Lab of Ornithology put out a great post on this subject.
- Diurnal aerial insectivores like Purple Martins dropped from the sky and roosted.
- Chimney Swifts that start circling their roost site at dusk began to do so.
- Crepuscular nighthawks were active.
- Nocturnal migrants dispersed.
More locally here in South Dakota, Dr. KC Jensen, of SDSU, reported the dawn chorus of many birds.