These are the relevant morphometrics to measure on a flycatcher. Although absolute measurements are very helpful, relative metrics, essentially proportions, are just as useful. These are the features that can be measured from photos or what you see, with some training, in the field.
Acadian Flycatcher migratory routes rewritten. In spring, most of the migration takes a largely land-based western circum-Gulf path. In fall, they take an easterly route through Florida and across the western Caribbean, bypassing most of Texas. Most fall Acadians in Texas are misidentified.
Nature research paper: A place-based assessment of biodiversity intactness in sub-Saharan Africa
go.nature.com/48i1GOU
Also an apparently new sp of Jewel Babbler in PNG..
#ornithology
onlinelibrary.wiley.com/doi/full/10....
Valid link to the paper:
mapress.com/zt/article/v...
@royalsociety.org the online format for this paper is now a bit of a mess - figures are not rendering and a pdf is no longer available!? can this be fixed?
Photo montage of Tinamus resonans sp. nov., a new species of tinamou from the montane forests of the Serra do Divisor, western Amazonia, Brazil. The species is distinguished by a unique combination of plumage pattern, vocal repertoire, and ecological characteristics, including a conspicuous dark slate facial mask, vivid rufous-cinnamon underparts, and a uniform brownish-gray back. Its vocalizations are remarkable, consisting of long and powerful songs that echo strikingly across the steep montane slopes, producing a characteristic resonant effect. The species was documented exclusively at higher elevations within a transitional zone between submontane and stunted forests, where the understory is densely structured by root mats. A preliminary population estimate, based on field detections and spatial extrapolation, suggests approximately 2,106 individuals restricted to the Serra do Divisor massif. Although no immediate anthropogenic pressures were observed within its range, the species may be highly vulnerable to climate change and to proposed infrastructure projects that threaten the integrity of this federally protected region. The discovery of T. resonans highlights the biological uniqueness of the Serra do Divisor, reinforces its status as a center of montane endemism, and underscores the critical importance of maintaining its long-term conservation.
Huge News from the Western Amazon: it's the year 2025 and we are still describing entirely new, strikingly-distinctive large-bodied bird species! Behold Tinamus resonans sp. nov. the Slaty-masked Tinamou mapress.com/zt/article/v... #Ornithology @tetzoo.bsky.social 🪶
Very cool Bill! I used to see them there every so often, including this remarkable song-switching individual I watched from a few m away flip flopping between Firecrest and Goldcrest song xeno-canto.org/437328
also we're missing something with Henicorhina. Remarkable how leucophrys here 'drops off' at about 1400masl with no obvious change in anything. Then at about 1100masl leucosticta occurs around streambeds etc. That sp pair remains puzzling to me, where in other sites they abut..
..mexicanus is v.common here and terri density is high which probably contributes. Some frantzii territories are in bamboo thickets etc.
Could also relate to nest choice (mexicanus usually in the back of a bromeliad, which themselves change with increasing elevation, species i think + densities)
thats a v good question..
My hunch for Catharus is that its something about structural complexity and how they use territories. mexicanus is very prominent and vigilant - sings constantly to defend territory. frantzii is much more skulky, often on the forest floor so could be a behavioural thing..
excellent new paper by Sam well summarized in this nice thread --- a TON of hard work went into testing these major hypotheses for range limits
cc/! @benjaminfreeman.bsky.social @sjportugal.bsky.social @josephtobias.bsky.social
Theres an urgent need to understand these mechanisms to make accurate projections of species responses to CC in tropical hyperdiverse regions.
..aside from the inherent interest in species ranges which naturalists of all shapes interact with daily (and that we have so much still to learn about!)
..but if not physiology (tracking thermal conditions that shift upslope), then why?
the answer is likely in complex relationships between competition&habitat which itself shifts at variables rates..
much to learn here in these combos -
www.science.org/doi/full/10....
www.pnas.org/doi/abs/10.1...
Why do tests like this matter?!
Understanding elevational ranges, allows us to understand elevational changes..
We know that tropical montane birds are shifting their ranges upslope.. (e.g. www.pnas.org/doi/abs/10.1...)
The answer appears to lie in habitat preference -
lower elevation (dominant) Catharus mexicanus, preferentially chooses open broadleaf forest and avoids fern dominated forest, excluding the higher elevation (subordinate) C.frantzii to habitats it doesn't want to occupy..
For Nightingale-Thrushes, an interaction between competition and habitat shape their elevational ranges.
The interaction between them is asymmetric (the norm in birds) - with the lower elevation species, dominant over its higher elevation counterpart.
So WHY NOT go higher up, if you can?
..with that info, we can test each hypothesis..
The upshot here is that thermal physiology has no bearing on where species CAN physically live (2x BMR suggested as the physiological 'ceiling' for species) - our species live comfortably within this.
So if not physiology, then what?
Then..
3. Measuring thermal physiology - what energetic cost to cold exposure does a species incur at different elevations?
4. Measuring microhabitat at every survey site
5. Experimentally testing how competition looks between species onlinelibrary.wiley.com/doi/full/10....
So i wanted to get mechanistic, and measure each of these variables on species and test them in unison, which meant:
1. Establishing abundance patterns across elevation by lots of point counts
2. Characterising the thermal environment birds experience across elevation..
3 key explanations-
1. Physiology (its too cold/hot at different elevations for a species to persist)
2. Competition between species limits distribution
3. Habitat (an ecological preference/specialism limits the range)..
There is nice work on each, but nothing pulling them together...
It was (still is..) wild to me that you can hike through the range edges of species.
Higher up = common, lower down = absent (or vice versa)
But what causes this?!
and why do species occur where they do?!
our understanding of what limits species ranges is still remarkably incomplete..
Check out our new paper in @royalsociety.org testing mechanisms behind elevational range restriction in tropical montane songbirds! ⛰️🦜🌳
Backstory: when i first visited Central America in the early 2010's i was struck with elevational ranges of birds..
royalsocietypublishing.org/doi/10.1098/...
I especially like your wand there 🦎🧙♀️
🦎THREAD: We just published something wild in @asn-amnat.bsky.social - lizards missing entire limbs not only survive, but some appear to actually thrive in the wild?!
Let me tell you about the "three-legged pirate" lizards 🏴☠️
[Paper: www.journals.uchicago.edu/doi/10.1086/... ]
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Novel game idea: geoguessing but with eBird checklists 🌎 🦢
Our paper about the flow of nocturnal bird migration through Colombia is finally out today in #ProcB! Using weather radars operated by the #IDEAM, we found that low variability in wind underlies a pace of migration that is far more gradual than at temperate latitudes. #Ornithology 📡🪶🇨🇴
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Love it- nice one!
We've just launched AviList! - the new unified global taxonomic checklist for the world's birds, developed through the Working Group on Avian Classification, including BirdLife, Cornell Lab of Ornithology, IOC and others @birdlifeglobal.bsky.social @birdsoftheworld.bsky.social www.avilist.org
