Breaking Down Science: An Article On Bird Migration And Climate Extremes

Ah, migration – what a wondrous time of year. The seasons are changing, birds are moving, and scientists are science-ing, or rather researching. However, none of this research is worth it if it’s not accessible to everyone. Articles can be heady and full of jargon that is confusing unless you are very familiar with the field of study. The article I’m going to write about is called “The implications of mid-latitude climate extremes for North American migratory bird populations” by Sorte, Hochachka, Farnsworth, Dhondt and Sheldon (hence forth referred to as Sorte, et al.). Basically, the researchers of this article took a bunch of data from eBird over a five-year period, and analyzed it to look at effects of climate extremes at mid-latitudes (see map below) on migratory bird species. They looked at short-distance vs. long-distance migrants occurring over non-marine areas; and used eBird checklists that were complete and that used either stationary, traveling, or area sampling methods of bird observations. It should also be noted that they did not look at anomalies such as accidental species (birds that got lost while migrating) or species associated with primarily marine environments (seabirds).


Mid-latitudes are located around 45 degrees North and South.

In case you weren’t aware, extreme weather and weather events are expected to increase over time. So, buckle up, fellow humans, the weather is going to get weird and it could be problematic for our fellow creatures, specifically migrating birds. The results of this study showed that basically some longer-distance-migrating species experienced climate-related stress during spring migration (primarily the month of March in this study) and then had a low productivity during the summer months (AKA breeding season for most creatures in the Western Hemisphere in non-tropical areas). However, the species that had a shorter distance to migrate seemed to show some resilience and flexibility when it came to dealing with the stress of climate extremes because they could detect changes and adjust. Migration is cued by seasonal changes, so if the changes occur at atypical times and birds follow those cues, then it can be problematic when extremes occur.

Why are these climate extremes a problem for migratory birds? Well, for species that have a long distance to migrate, these birds are expecting the weather to be a certain way upon arrival, and are unlikely to be able to detect and adjust for seasonal climate extremes during migration. If it’s incredibly hot or cold or there’s an intense storm, that will take away precious energy resources typically used for breeding. This will result in getting allocated to feeding and/or protecting themselves, and keeping warm or cool when they normally would not have to.

Enjoy this blackpoll warbler, who breeds in boreal coniferous forests of Canada and Alaska in the summer. In the fall, these birds fly 1500 miles nearly non-stop down to eastern South America. This species is a long-distance migrant.

While this study looks at a lot of data and presents interesting findings that are probable, I believe more research needs to be done. Since everyone and anyone can submit to eBird, there are varying skill levels and not all observations may be accurate. I think that perhaps if this study only contained checklists from well-known, experienced birders, scientists, and researchers, then the data may be more credible.


Fantastic Friday: Creches

Today this French-based term isn’t about a tableau for the birth of Jesus, or a British daycare or nursery. This is about animal behavior and the communal care and raising of young. This is a behavior that is exhibited by some bird species, particularly aquatic-based birds such as ducks, geese, eiders, penguins, and cormorants.

Female Mallard with ducklings. Washington, D.C. May 2016. Photo credit: Heather L. Kostick
Female Mallard with ducklings. Washington, D.C. May 2016. Photo credit: Heather L. Kostick

So, how does this even happen? Well, in some cases it’s just parents feeding the wrong kid, like in the case of cliff swallows who are colonial nesters. In other cases, there could be a territory dispute between females with young in tow, and a mix-up of children happens, and they end up with a different mother than they arrived with. However, sometimes it’s just moms teaming up and taking the “it takes a village” approach to parenting. Sometimes even non-breeding females will assist with the care of the young. I observed an example of a creche in D.C. when I was in town for the National Geographic BioBlitz, when a female Mallard had three ducklings in tow, and one of them was decidedly younger than the other two (not pictured). A National Park Service ranger informed me that it’s very common in the Constitutional Gardens to see that sort of thing, and that it was probably poor parenting on the other hen’s part that led to the hen I saw with the mixed-ages young.

So, this is mostly a bird behavior, but there are mammals, such as humans (ever drop know a kid dropped off to a daycare center?) and lions, that exhibit this behavior. It’s pretty cool to see instances of what could be considered adoption and/or daycare in species outside of Homo sapiens.

A little more information and examples:

Brandt’s Cormorants


African Lions 1

African Lions 2 

Thesis Stuff: June Bioblitz A Success

Holy hoonah! That phrase about sums up my June bioblitz for my capstone work, which was a success if I do say so myself. I’m still working on the species count, but it’s looking like we will break last year’s 299 record. Until I have a pretty chart or graph to post, take a look at some pictures from the day.

(photo credit: Heather Kostick)

Mama tree swallow peaking out of her nest box - sorry for bothering you, mama, but I was chasing insects.
Mama tree swallow peaking out of her nest box – sorry for bothering you, mama, but I was chasing insects.
fairy ring fungi in mint
fairy ring fungi in mint
Sphinx attracted to the mercury lamp sheet
Sphinx attracted to the mercury lamp sheet