Claim: Long-Term Decrease in Coloration: A Consequence of Climate Change?

This paper appears to be sort of the opposite of p-hacking, instead of choosing one effect out of many to be from the cause, they assert one cause out of many to have caused the observed effect.

Long-Term Decrease in Coloration: A Consequence of Climate Change?

David López-Idiáquez, Céline Teplitsky, Arnaud Grégoire, Amélie Fargevieille, María del Rey, Christophe de Franceschi, Anne Charmantier, and Claire Doutrelant


Climate change has been shown to affect fitness-related traits in a wide range of taxa; for instance, warming leads to phenological advancements in many plant and animal species. The influence of climate change on social and secondary sexual traits, which are associated with fitness because of their role as quality signals, is, however, unknown. Here, we use more than 5,800 observations collected on two Mediterranean blue tit subspecies (Cyanistes caeruleus caeruleus and Cyanistes caeruleus ogliastrae) to explore whether blue crown and yellow breast patch colorations have changed over the past 15 years. Our data suggest that coloration has become duller and less chromatic in both sexes. In addition, in the Corsican C.c. ogliastrae, but not in the mainland C.c. caeruleus, the decrease is associated with an increase in temperature at molt. Quantitative genetic analyses do not reveal any microevolutionary change in the color traits over the study period, strongly suggesting that the observed change over time was caused by a plastic response to the environmental conditions. Overall, this study suggests that ornamental colorations could become less conspicuous because of warming, revealing climate change effects on sexual and social ornaments and calling for further research on the proximate mechanisms behind these effects.

Here is the press release

Research suggests that change in bird coloration is due to climate change

Blue tit



The study was carried out over a 15-year period in the south of France through a partnership between scientists from the UPV/EHU-University of the Basque Country and the Centre d’Écologie Fonctionnelle et Évolutive (CEFE-CNRS) in Montpellier

Peer-Reviewed Publication


The work, which was conducted over a 15-year period (2005-2019) through a partnership between scientists from the UPV/EHU and the Centre d’Ecologie Fonctionnelle et Évolutive in Montpellier (CEFE-CNRS), focused on two populations of blue tits in the south of France, one located on the outskirts of Montpellier and the other in the northwest of the island of Corsica. 

Each year between 2005 and 2019, all breeding blue tits in each population were captured. As a result, researchers from the two institutions were able to gather more than 5,800 observations on the colouring and other characteristics of the blue tits.  

The blue tit is characterised by its striking colouring: a blue crest and a yellow breast. The results obtained in the study show a decrease in both populations of blue and yellow colouration between 2005 and 2019. In other words, the blue crests and yellow breasts of blue tits in these two populations are on average less colourful right now than when the research began.  

“Our work suggests that environmental changes, and specifically climate change, could be the main reason why birds such as the blue tit are undergoing a change in their physical features, more specifically in the brightness and intensity of their colouration,” said David López-Idiáquez, researcher in the UPV/EHU’s Department of Plant Biology and Ecology.   

“A negative trend in terms of brightness and intensity of plumage colouration in both sexes and populations has been observed, although in Corsica this change is more associated with climate,” explained López.” The change in plumage colour seems to be the result of a combination of a rise in temperature (1.23ºC) and a fall in rainfall (0.64 mm), so climate change would be the potential cause of this difference,” he said.   

Change in species mating patterns 

It may appear to be a purely aesthetic change, but just the opposite is true, as this change in plumage may have an effect on the “mating patterns” of the species. “In these birds, traits such as colouring function as signals to indicate to other individuals the quality of the specimen, which are decisive, for example, when it comes to breeding,” explained David López. 

“This study was possible thanks to the continuous monitoring of the two blue tit populations for more than 15 years, which highlights the importance of long-term studies to understand the effects of climate change on the ecosystems around us,” he said. 

When there is a variation in the territory, animal populations have 4 options: the first is to undergo genetic change; the second is to undergo plastic change (change in physical characteristics without genetic changes); the third is to migrate; and the last, to disappear. “It is important to stress that this change is not genetic but plastic, one of the ways of adapting to new environmental conditions,” he pointed out. 

Change in our environment 

“Given that our environment is quite similar, albeit less hot, our birds may be undergoing the same change,” surmised David. “In any case, there are only four studies of this type in the world, and none of them has been carried out in the Basque Country; I think it would be very interesting to carry out more research like this not only on a Basque level, but also on a national level,” he added.  

David López-Idiáquez (Villajoyosa, 1988) is a postdoctoral researcher at the University of the Basque Country and at the Centre d’Ecologie Fonctionnelle et Évolutive in Montpellier. His research interests focus on understanding how the heterogeneity of environmental conditions alters evolutionary dynamics, especially in ornamental traits. After graduating from the UPV/EHU, he was awarded a PhD in Ecology from the Autonomous University of Madrid in conjunction with the Museum of Natural Sciences in Madrid. 


The American Naturalist




Long-Term Decrease in Coloration: A Consequence of Climate Change?



Quick spit balling of other possible explanations

1. Capturing all the breeding pairs every year for 15 years may have impacted the health and well-being of the community of blue tits.

2. Maybe they didn’t capture them all and the ones that got away were less colorful, harder to see, and caused drabness to be inherited.

3. Perhaps the change is caused by adaptation to a world that is becoming less colorful.

4. Perhaps a consequence of genetic isolation and minor inbreeding.

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Paul S.
August 3, 2022 2:13 pm

I know a bit about blue balls, but not so much blue tits

Reply to  Paul S.
August 3, 2022 3:11 pm

former is long term local climate;
latter is short term weather.

Reply to  Paul S.
August 3, 2022 4:05 pm

Brings back memories of that famous article a few years ago “Great Tits cope well with warming”

Willem post
Reply to  Paul S.
August 4, 2022 6:46 am

The he and she birds are confused by wokeness, so they mix their colors.
What a mess.

August 3, 2022 2:32 pm

Blue on top, yellow lower, clearly the birds have an Ukrainian connection. Fading colors could mean less support…..

Gerry, England
Reply to  CharlesMartell
August 4, 2022 5:25 am

Fading colours are a good indicator of how the Ukrainian army are doing.

Willem post
Reply to  Gerry, England
August 4, 2022 6:45 am

Ukraine will run out of soldiers before Russia will.
Remember, the industrial base is mostly in the east, now controlled by Russia.
Europe and the U.S. have no spare one $TRILLION to put Ukraine back together again.

Reply to  Willem post
August 4, 2022 10:11 am

Yeh, so far 1/3 of all Russian forces are no gone, VDV is history for now, and Russia sends T62 and other equipment of 1950-ies :D.
Remember the winter war? Its seems that soviets sudenly run out of army +22k loses vs around 120k.
And industrial base is not under controll of Russia, there is no industrial base left behind, but now its seems that Russians run out of the money for army, becouse to find idiots how wants to go in Ukraine after they got not payed for this now declaining fast, Russian army is good, as always, thru meat and enemy, human cost is nothink for them, baby narazhajut 😀

lee riffee
August 3, 2022 2:32 pm

I swear….do the writers of this kind of drivel realize that the ancestors of birds (aka dinosaurs) had a very long and very successful reign? Maybe they have heard of dinosaurs, but clearly they don’t seem to realize that the entire world was much hotter 65+ million years ago. But hey, that was so long ago surely everything must have been in black and white, right? All of those paleontologists and paleoartists must be wrong – the dinosaurs must really have been a dull-looking bunch, living in a world with no ice caps!
But seriously, if even just a few of these “scientists” knew history, (not just human history but geological and paleontological history especially) they might not come up with this kind of nonsense.

Reply to  lee riffee
August 3, 2022 3:28 pm

You see signs that some of them know something about human history?

Reply to  lee riffee
August 3, 2022 8:35 pm

When trees grew like grass and there was enough flora to keep herds of 100-ton herbivores fed.

Reply to  lee riffee
August 4, 2022 10:09 am

Sadly, nonsense sells.
Indirectly this site contributes by airing such drivel, but its entertaining all the same.

Reply to  Rocketscientist
August 4, 2022 1:33 pm

Watts was just curious about how many comments would concentrate on the line about blue tits.

Richard Page
Reply to  lee riffee
August 5, 2022 9:58 am

The ‘study’ is an absolute load of crap. There was an earlier study published in 2016, following 40 years of careful study, started by Blondel, that showed diversity amongst at least 3 sub-species of mediterranean blue tit. Mainland blue tit’s showed different colour and male size differentiation between evergreen and deciduous habitats; the Corsican blue tit showed paler colour variation. The reason was caterpillars – all 3 subspecies feed on them but the caterpillars emerge at different times depending on the habitat – evergreen, deciduous then Corsica. When your feeding habits and egg-laying cycles are happening at different times, it helps the individual birds to know the difference between the groups – it’s just adaptation at work.

August 3, 2022 2:32 pm

What next?

Gregory Woods
Reply to  HenryP
August 3, 2022 2:43 pm

Tigers with fading stripes…

Rud Istvan
Reply to  Gregory Woods
August 3, 2022 3:36 pm

Corals with fading colors is a VERY popular concern for GBR.

Geoff Sherrington
Reply to  Rud Istvan
August 3, 2022 5:31 pm

Australian news an hour ago claimed the whole Great Barrier Reef showed growth over the last year and now had the most cover yet measured. Aust Inst for Marine Science AIMS claims reduced harm from less heat stress and no cyclones. Geoff S

Paul S.
Reply to  Gregory Woods
August 3, 2022 4:54 pm

You know, I used to have brown hair, not it is grey. climate change?

Reply to  Paul S.
August 3, 2022 5:12 pm

Yeah, now that you mention it, my hair was much darker in the early 70’s when I was in college and it was much colder. Hadn’t thought about climate change. Good catch.

John Hultquist
Reply to  BobM
August 3, 2022 7:19 pm

Do students at Edmonton University have black hair?
I’ll investigate for $200,000.

Reply to  BobM
August 3, 2022 11:57 pm

It was much hotter in 1976, for months.

Reply to  Chaswarnertoo
August 4, 2022 10:11 am

So was I

Reply to  Rocketscientist
August 4, 2022 1:39 pm

Good one!

Reply to  BobM
August 4, 2022 9:42 am

mine was blond/very light in the 60’s. In the heat of the 80’s it darkened to what others even said was brown. Now it is slowly becoming lighter again … like yours.

Obviously related to global temps, but also shows that we are going into a cooling phase.

Reply to  BobM
August 4, 2022 1:38 pm

I’ve been shaving my head now for several years (no, I have not totally spent the time in that pursuit), in order to confuse Mother Nature. Now that my pate is ‘browning’, I’m getting that old “now we can see you’re full of ….”.

Reply to  Paul S.
August 4, 2022 10:10 am

Unfortunately is my internal climate change.

Reply to  Gregory Woods
August 4, 2022 12:42 pm

leopards changing their spots

Reply to  HenryP
August 3, 2022 4:08 pm

Human sacrifice, dogs and cats living together… MASS HYSTERIA!” – Dr. Peter Venkman

We’ve definitely got the last one, and maybe the first… best keep an eye on your pets.

Right-Handed Shark
August 3, 2022 2:48 pm

Charles, you missed another possible explanation:


william Johnston
Reply to  Right-Handed Shark
August 4, 2022 6:39 am

But that would be unethical. Or something.

alastair gray
August 3, 2022 2:51 pm

Eight scientists collaborated on this monumental paper. What did they al do to earn their research grants. Surely one scientist would have been enough. However when you think about it rotten as this paper appears to be it is one of the better climate science papers

Gerry, England
Reply to  alastair gray
August 4, 2022 5:27 am

It is common practice to get a few ‘big names’ on board to boost the prestige of a paper. Little Mikey Mann loves to make guest appearances and it makes it look like you have done more work than you actually have.

Richard Page
Reply to  alastair gray
August 5, 2022 10:01 am

It really isn’t – see my post above. It’s garbage and, worse, it’s easily refuted garbage at that.

August 3, 2022 3:14 pm

I know people that breed blue tits….their color is highly variable….and keeping the blue is the hardest to do…this is genetic

Reply to  Latitude
August 3, 2022 3:31 pm

Or possibly epigenitics, influenced by recent conditions which could include captivity or some common conditions of captivity.

Rud Istvan
Reply to  AndyHce
August 3, 2022 3:38 pm

If epigenetics, then there is a simple explanation. Capturing them to study scared them so badly they went pale with fright.

Reply to  Charles Rotter
August 3, 2022 10:16 pm

My thought was that they were getting duller so they wouldn’t stand out so much and be harder to catch. Then I saw your suggestions and thought, great, he beat me to it.

Joao Martins
Reply to  Brad-DXT
August 4, 2022 3:49 am

One of my professors of zoology at the university has studied that, more than 50 years ago: the “adaptive” (call it “adaptive” to simplify) nuancing of color of populations of a bird according to the color of the surroundings of those populations in the Iberian Peninsula. Similar to Biston betulara.

Reply to  Rud Istvan
August 3, 2022 9:26 pm

If epigenetics, there are probably a great many possible mechanisms at play.

Hoyt Clagwell
Reply to  AndyHce
August 3, 2022 10:09 pm

Possibly dietary changes, the same way pink flamingos get their coloring from their particular shrimp diet.

Reply to  Hoyt Clagwell
August 4, 2022 1:42 pm

True? I didn’t know that…. thanks.

Richard Page
Reply to  Hoyt Clagwell
August 5, 2022 10:04 am

Sort of. Flamingo’s eat shrimp and algae, shrimp eat algae and it’s actually the algae that gives them that colour.

Rud Istvan
August 3, 2022 3:31 pm

I did some quick research before commenting. Easy, since blue tits are a beloved bird in Europe. What a pathetic piece of junk science this new paper proves to be.

Some blue tit facts. There are an estimated >20 million in Europe. Average lifespan in the wild is about 3 years, but up to 10 is known from banding studies. The breeding pairs are monogamous, and they return to their same breeding site (tree hole, nesting box) every year. Average clutch is 7-8 eggs, but there is high fledgling mortality from Blue Jay nest and sparrow hawk fledgling flight predation. They are non migratory, but their summer/winter range covers a few miles. Depth of coloration depends somewhat on diet (more yellowy-green caterpillars makes a more intense yellow breast). Younger birds generally have more intense coloration than older birds. (This may be evolutionary, as more intense color is thought an indicator of ‘robustness’ in seeking a mate for life.)

Some study facts. 5800 observations over 15 years is an average of 387/yr–very small annual sample of a very large general population to reach such a general conclusion. Sampling spanned an average of only (15/3) an average of just 5 generations—if study conclusion was close to right, it would have found the fastest evolutionary change ever. Even farm animal selective breeding isn’t that good. No age control, yet younger blue tits are KNOWN to be more colorful—so the finding could just be random age mix change in the small sample. Finally, one of the chief mortality events is a cold wet late spring during breeding season, since the adult birds have to forage harder for their chicks despite bad weather and fewer insects—so the hypothesized climate change/coloration change could simply be more birds surviving beyond 3 years in a slightly milder climate, changing the sample age ratio toward older and duller.

The final BIG problem with this paper is that the climate in the study survey area didn’t change much at all during the study period 2005-2019. Pause one, an El Niño, then pause two. Oops. more new junk climate science on several grounds.

Ron Long
Reply to  Rud Istvan
August 3, 2022 3:49 pm

Come on, Rud, you only did “…quick research…” before commenting to give yourself enough time to talk yourself out of your initial idea about commenting on “blue tits”. OK it takes one to know one?

Joao Martins
Reply to  Ron Long
August 4, 2022 3:51 am

“Tits” (blue or otherwise) deserve long research efforts in the field.

Last edited 1 month ago by Joao Martins
Reply to  Joao Martins
August 4, 2022 1:46 pm

It should also be the type of study known as “hands on”, to be of any use.

Reply to  Rud Istvan
August 3, 2022 9:49 pm

There’s also the African Blue Tit

Reply to  Rud Istvan
August 4, 2022 1:58 am

Thanks Rud – your ‘quick research’ is impressive. I think the age pattern is conclusive enough for me – random noise in their data.

The Dark Lord
August 3, 2022 3:32 pm

I mean, I can understand how the researchers got caught up in this work … imagine the deceptive job ad … “Exciting opportunity to spend the next 5 years staring at tits” …

Reply to  The Dark Lord
August 3, 2022 9:51 pm

imagine the deceptive job ad … “Exciting opportunity to spend the next 5 years staring at tits”

In the UK that would mean they stare at each other.

It seems that’s exactly what they did

August 3, 2022 3:34 pm

I wonder what is to blame for Greek and Roman statues being kept dazzling white for so many years when research has shown they were actually dazzling colors, as evidenced by traces of paints.

Was it white supremacy, or was it climate warming? And if climate warming, was it the Roman Warming Period when so many were made, or the Medieval Warming Period when so many were discovered, or Modern Warming when gender fluidentity studies uncovered the truth? The intersectionality of these recent events is very disturbing.

Reply to  Felix
August 3, 2022 5:17 pm

The nekkid women statues, if they were painted, what color were their tits?

Were these birds named after ancient statues of women? Do these birds provide a glimpse into ancient history?

(Oops! I shouldn’t have written that. That gives lots of room for grant requests for follow-up studies. Sorry.)

The Dark Lord
August 3, 2022 3:36 pm

how did they find causation between climate change (whatever that means today) and fading colors … the climate is ALWAYS changing … Darwinian theory would assume the colors fading over time (less visible to predators) no matter what the climate is doing (this week)

Matt Kiro
Reply to  The Dark Lord
August 3, 2022 8:37 pm

Did they even show evidence of a changing climate? A slight variation in temperature is hardly a change in climate.

Hoyt Clagwell
Reply to  The Dark Lord
August 3, 2022 10:14 pm

Ironically the birds with the most saturated colors seem to come from the warmest parts of Earth. Colors can be a warning of toxicity as well where Darwinian theory might say that bright colors cause predators to avoid you.

Reply to  Charles Rotter
August 4, 2022 2:01 am

That seems very likely to me. Who would set out on a 15 years study to measure colour brightness alone.

Richard Page
Reply to  Charles Rotter
August 5, 2022 10:10 am

If they did only consider colour variation, then they completely missed the fact that males in evergreen habitats are smaller than males in deciduous habitats. As I posted above, an earlier study showed it’s down to an adaptation to different feeding times – sod all to do with climate change.

Mike Smith
August 3, 2022 3:53 pm

It seems the taxpayer is picking up the tab to keep literally thousands of “researchers” engaged in this type of “science”. It’s stupid, shameful and maddening.

August 3, 2022 4:00 pm

Blue tits are less blue. Obviously the result of a less cold world.

Captain climate
August 3, 2022 4:14 pm

15 years is not a climate timeframe. Whoever approved this paper should be defenestrated.

August 3, 2022 4:22 pm

Research like this is a top reason why Biologists, as ‘professionals’ , are the 2nd poorest in terms of pay scale. Only those who are in fields of theology are paid less.

Ed Hanley
August 3, 2022 4:23 pm

A note to David López-Idiáquez, Céline Teplitsky, Arnaud Grégoire, Amélie Fargevieille, María del Rey, Christophe de Franceschi, Anne Charmantier, and Claire Doutrelant –

Charles Darwin is ashamed of you.

Moderately Cross of East Anglia
Reply to  Ed Hanley
August 4, 2022 12:04 am

Charles Darwin? Who cares? Alfred Russell Wallace is whose opinion you should be concerned about.

Why don’t they just buy a few spray cans of paint and get creative, the Tits won’t mind.

August 3, 2022 4:50 pm

Oh, I’m sure they isoloated all the variables.

Gordon A. Dressler
August 3, 2022 5:04 pm

Why not?

After all, climate change has already been cited as the causative agent for coral bleaching.

/sarc off

August 3, 2022 5:12 pm

Color convergence through interdiversity sex.

Geoff Sherrington
August 3, 2022 5:44 pm

Paper claims 1.23 deg C temperature rise moved 15 years. This is far, far greater than usual, such as UAH global showing about 0.2 to 0.3 deg C over those 15 years.As for their rainfall reduction, this is so small that it hard to see it as an influence,. Geoff S

Rich Davis
Reply to  Geoff Sherrington
August 3, 2022 6:25 pm

Rainfall reduction? I thought it was 6% wetter. Help, griff! Is it fake news?

August 3, 2022 6:01 pm

Much more likely due to a Darwinian selection to the world’s overpopulation of housecats. Cats don’t distinguish colours as well as humans do, so brighter coloured birds aren’t as well camouflaged and get to be cat lunch more often. But hot weather selectively killing brighter coloured birds could be a hypothesis worth checking as well…./s

Reply to  DMacKenzie
August 3, 2022 8:50 pm

Or maybe ultraviolet trippy is the hot new trend with these birds right now (most birds can see into the ultraviolet spectrum). Did anyone try holding some feathers up to a blacklight?

Peta of Newark
August 3, 2022 6:59 pm

Some well-intentioned person(s) within the test area has been feeding the little birds.
Yes very lovely and nice and probably to some (great) extent is what kept the population alive.
Certainly in the UK (and the minds of most WUWT commentators), the corvids and raptors that eat those little birds have become revered and protected.

Thus ‘artificial’ feeding would serve 2 main purposes:
1/ Keep the population large and viable in the face of food shortages
2/ That the tits are less frightened of humans than the raptors are works as a potent defence/protection mechanism

The downside for the tits would be that the ‘food’ they were being given and were eating would be similar to the nutrient-free tasteless mush that humans themselves now eat.
iow: it would revolve around grains, classically wheat

Soooo, what sort of nutrients do the birds need use to make their colours? i
It’s a pretty sure bet they are not going to find them eating grain – with the result they will become dull and boring.
Cobalt was always good for making things= Blue but Chromium is the mother & father of all things blue and yellow

Well hello hello, just about sums up the entire human condition right now, Dull & Boring
Esp when the likes of BoJo and Brandon were the ‘most colourful’ specimens that could recently be found
Hmmm, by contrast, is Mr Putin a cnut-struck diabetic and demented dipsomaniac?
(Oddly enough, dietary Chromium is vital in fending off Diabetes and not often listed as a nutrient to be found inside bottles labelled ‘Pinot Gluggio de la Plonkio)

That was= Serious Question re Putin, I don’t personally know the guy but from what I see, I suspect he is none of those things

The little birds are trying to tell us something – yet the very folks who go there to listen are themselves so dull and boring, they only hear what they expected to hear. They didn’t go there to look listen and learn at all.

Leaving aside the fact that those folks consider 15 years to be ‘long term
Errrr, did they not get the memo, ain’t climate supposed to be 30 years long, at least?
Course they didn’t, they were out at the local Wine Bar, a pizza on the way home and the next day asleep & hung-over in front of the office/laboratory computer
Now that’s the way to do science these days.

Surprise surprise, wrong piled upon wrong upon ever more wrong

Last edited 1 month ago by Peta of Newark
Richard Page
Reply to  Peta of Newark
August 5, 2022 10:11 am


John Hultquist
August 3, 2022 7:16 pm

“… more than 5,800 observations(captured) collected on two Mediterranean blue tit subspecies (Cyanistes caeruleus caeruleus and Cyanistes caeruleus ogliastrae) to explore whether blue crown and yellow breast patch colorations have changed over the past 15 years. Our data suggest that coloration has become duller and less chromatic in both sexes.”

Were this done to you, would you not try to be less conspicuous?
15 years of climate change — Come on, man!

August 3, 2022 9:53 pm

I’m fully on board with this study

After all, it’s not as though there are any colourful birds in the tropics, is there?

Waaait a minute….

Reply to  Redge
August 4, 2022 8:55 am

This year has seen Bee Eaters breed in the UK…

Bee-eaters in Norfolk ‘worrying sign of climate change’ – BBC News

Reply to  griff
August 4, 2022 9:53 am

So what?

We’ve had scorpions living and breeding in the UK for over 150 years

Prove CO2 is the cause

August 3, 2022 10:07 pm

I have noticed that the blue tits are getting paler. However, the great, coal and long-tailed that we see at our feeders are not. Anecdotal I know. But surely all varieties would be affected equally?

Reply to  Bil
August 4, 2022 4:40 am

That might be evidence of the dietary changes suggested by Peta of Newark above. They might all be consuming less cobalt and chromium but it only impacts blue/yellow colouration.

August 4, 2022 12:25 am

Gosh – what insightful stuff. FINALLY, I understand why my hair is losing its colour!

Andy H
August 4, 2022 12:43 am

Here in the UK I would definitely expect blue tits to become less brightly coloured because we now have sparowhawks everywhere. I wonder if France is similar.

August 4, 2022 1:50 am

Let me suggest:

5. Noise in the data and no real change in colour.

From the abstract (full article is paywalled):

Our data suggest that coloration has become duller and less chromatic in both sexes. In addition, in the Corsican C.c. ogliastrae, but not in the mainland C.c. caeruleus, the decrease is associated with an increase in temperature at molt.”

Different results re temperature in the two populations. So how can one conclude anything about temperature? Generally, birds are brightest after they have put on their new plumes before breeding and decline as they struggle to raise their young. One wonders how long the trapping season was and also how consistent their estimate of colour was over the 15 years. This looks like data mining to produce a pre-determined result, not a study that set out to look for changes in plumage brightness over time.

Reply to  DaveW
August 4, 2022 5:04 am

“associated” is an interesting word choice. They could have used ‘correlated’. Their data only “suggest” that coloration has become duller, and they are only able to conclude that their study “suggests” that something “could” be happening because of warming. Then they call for more research (i.e. more lucrative research grants) into the mechanisms for the changes that they suggest could be happening. Hmmm. Are we really supposed to take this seriously?

Joao Martins
August 4, 2022 3:36 am

Long-Term Climate Change: A Consequence of Climate Change?

August 4, 2022 6:26 am

Another argument for shutting down all the universities & terminating government funding of “science” “research”.

Dan Sudlik
August 4, 2022 6:58 am

15 years is NOT long term, it grant after grant after grant might be😡

Reply to  Dan Sudlik
August 4, 2022 2:19 pm

Actually, if the study was to be a longer one for some (desired?) accuracy, they should have to vote counters from Arizona involved.

August 4, 2022 5:08 pm

“In other words, the blue crests and yellow breasts of blue tits in these two populations are on average less colourful right now than when the research began. ”

Atrazine? I’ve read that male birds are most often colourful compared to their female counterparts. If chemicals are changing them into females, then seems logical that they’ll lose their color.

Probably reason why our T levels have been dropping for decades. (Good for slowing population growth.)

August 4, 2022 6:44 pm

Each year between 2005 and 2019, all breeding blue tits in each population were captured.”

Exactly, how do they know they’ve captured every breeding pair?

And these dimwits have the temerity to state:

Our work suggests that environmental changes, and specifically climate change”

Seems to me that the greatest impact on the breeding pairs of blue tits are the silly students who chase them until they’ve caught, checked for a band and banded all breeding birds missing a band!

Suggests“, they should suggest their own idiocy as the cause.

I doubt those breeding pairs were as eager after the students got through with them. A shock that likely affected the bird’s diets as well as their breeding.

michael hart
August 5, 2022 8:05 am

When the first sentence of the abstract opens with “Climate change…”, you know where it’s going. And it’s not going in the direction of science.

jim hogg
August 6, 2022 1:36 am

Or maybe their visual acuity/sentivity has increased and less saturated hues do evolution’s work just as well. Tetrachromatic avian color perception is complex, isn’t static, and it may have changed slightly for any of a number of reasons, without a detectable genetic component being affected. I hope this research was privately, and not taxpayer, funded!

August 6, 2022 4:38 am

much much much more likely its due to land-use obliterating an entire slice of their available diet

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