
Global warming-induced migratory bird body size reduction and shape change - bookofjoe
https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.13434
======
shealutton2
Given that HN has had articles on the decline of the insect population
([https://en.wikipedia.org/wiki/Decline_in_insect_populations](https://en.wikipedia.org/wiki/Decline_in_insect_populations))
and the decline in bird populations
([https://www.nytimes.com/2019/09/19/science/bird-
populations-...](https://www.nytimes.com/2019/09/19/science/bird-populations-
america-canada.html)), I am surprised that food supply is not listed as one of
the causes of body changed.

~~~
neo4sure
here you go [https://www.scientificamerican.com/article/does-global-
warmi...](https://www.scientificamerican.com/article/does-global-warming-make-
food-less-nutritious/)

~~~
chrisco255
Macronutrients shift by minor amounts (single digit percentages), but there is
more overall food. CO2 causes a more efficient use of water in photosynthesis
and improves overall crop yields. The last time CO2 was in the thousands of
PPM, the ancestors of birds...AKA dinosaurs...thrived and grew to enormous
sizes.

~~~
inetknght
But I don't think dinosaurs were plagued by microplastics and poisons
industrially designed to kill them instead of their food supply.

------
smackay
There are few details in the abstract but wing length is notoriously difficult
to compare across measurers - the standard method of measuring the leading
edge of the wing by gently straightening the primaries along a stopped ruler
can easily generate differences of 2-3mm for different people measuring the
same bird. It can be done for small groups of people who work together - wader
ringers (shorebird banders if you are in the Americas) where they deliberately
practise to standardise their technique. If the sample sizes are good then the
error should be consistent across time so the conclusion might still be sound.

[https://en.wikipedia.org/wiki/Bird_measurement#Wing](https://en.wikipedia.org/wiki/Bird_measurement#Wing)

The good news from this is that nature is splendidly adaptable and able to
compensate for changes that occur within a few decades. That says that plants
and animals are a lot more robust than we think they are.

UPDATE: One confounding factor is that standards in handling birds are always
improving so there's no way of telling whether measurements are comparable
across time.

UPDATE: Thanks to throwaway5752 for finding the full text. The birds were
measured by a single observer so you can ignore everything I said. Interesting
result.

------
romaaeterna
There have been huge changes in habitat during the same period, driven largely
by urbanization and changes in agricultural patterns, that dwarf any changes
driven by climate. We actually had Ectopistes migratorius go completely
extinct by 1901, due to habitat destruction, not climate change.

~~~
mempko
Climate change at the human accelerated rate IS habitat destruction.

~~~
romaaeterna
But the important thing is the rate. How would you measure the habitat
destruction? Distinct species per unit area? Biomass per unit area? Climate
change affects no possible proxy that you could select as fast as a bulldozer
and a housing development. (And in recent years, climate change has been
positive for global biomass.)

~~~
cmendel
Yes, but you are conflating local effects with broader trends. A housing
development may result in the partial or total habitat destruction of a couple
of species, climate change is causing the destruction of a double digit
percentage of all species across the board.

~~~
romaaeterna
As of yet, actual habitat destruction by humans has wiped out far more species
across the board than climate change has. Perhaps that will change some time
in the future.

------
chiefalchemist
Birds eat insects, yes? If there's been a reduction in insects then wouldn't
that impact birds' development?

------
allovernow
I don't have access to the article, and there really isn't anything given in
the abstract to actually link the change in body size to global warming. I
hope the article does a better job than "warmer temperatures are expected to
reduce bird size and here are a bunch of bird species which have gotten
smaller over the last 4 decades, therefore climate change."

~~~
throwaway5752
It is a scientific paper, not an "article". The abstract is pretty clear
summarizing the findings and I'm not sure what you would otherwise expect from
the abstract of a paper.

When I search for the paper's title, I found the full text on the third result
[https://www.biorxiv.org/content/10.1101/610329v1.full](https://www.biorxiv.org/content/10.1101/610329v1.full)

edit: leaving as is but, "research article" or "paper", i was replying to the
common usage meaning of "article". Anyway, my point about the abstract stands
and the rest of the paper supports it well.

~~~
there_the_and
A scientific paper is a type of article.

