Shifts seen in breeding times and duration for 73 boreal bird species
over 40 years
UMass Amherst ecologist, part of Finnish team, used 820,000 nesting
records

Date:
July 23, 2020
Source:
University of Massachusetts Amherst
Summary:
Forest ecologist report finding ''clear evidence of a contraction
of the breeding period'' among boreal birds in Finland over a
43-year span for which good quality data were available.



FULL STORY ==========================================================================
In a new study out this week, a team including forest ecologist Malcolm
Itter at the University of Massachusetts Amherst reports finding "clear evidence of a contraction of the breeding period" among boreal birds in
Finland over a 43- year span for which good quality data were available.


==========================================================================
The study was run by researchers within the Research Centre for Ecological Change (RCEC) at the University of Helsinki, led by Maria Ha"llfors with
Itter and Laura Anta~o, all postdoctoral researchers at the time. They
were joined by additional researchers at the Swedish University of
Agricultural Sciences and the Finnish Museum of Natural History. Details
appear in Proceedings of the National Academy of Sciences.

Itter says that for most of the 73 species studied, "we saw an advance
in the beginning of the breeding period," an average 4.6 days, and the
breeding period ending earlier, an average of 6.3 days. The average
breeding period contracted by 1.7 days over the period with a breeding
period contraction in roughly 31 percent of all species.

The researchers report that "this pattern was most common among resident
and short-distance migrating species." This suggests that residents and
short- distance migrants "may be better able to respond to increased temperatures in the spring and thus take better advantage of the earlier
food and resource availability," while "long-distance migrants that
arrive later may not be able to do so," Itter explains.

This study is unusual, as researchers looked not only at the onset
of the breeding period, but also its end, and duration. They used
"unique and extensive long-term bird-banding data" collected over 43
breeding seasons by a small army of experienced, dedicated banders --
called ringers in Europe. Tits, thrushes, crows, owls and gulls showed
the greatest changes in breeding period.

"Any species that had a contraction had an earlier end to the breeding
season," Itter notes.

The authors state, "Our findings highlight the importance of quantifying phenological change across species and over the entire season to reveal
shifts in the community-level distribution of bird reproduction." And,
"most importantly, our study suggests that evaluating changes throughout
the season is crucial, as earlier and shorter breeding periods in birds
may alter community-wide patterns of species co-occurrence and trophic relations across the boreal region." Ha"llfors, Itter and colleagues'
main hypothesis was that as conditions warm, they should see food
and other resources become available earlier in the year, and because temperature is the cue for favorable conditions to rear chicks, warmer
springs may cause the breeding period to shift forward.

They used a creative combination of techniques for data analysis,
including a modeling framework developed for natural community data
and primarily to predict species' range shifts. The model framework was
applied in this case to jointly estimate changes in the breeding period
of a boreal bird community - - breeding beginning, end and duration.

The model included evolutionary history information; the study found
that species that shared evolutionary history shared similar breeding
shifts. "From a methodological perspective, our study illustrates that
a focus on quantifying phenological advances alone may mask important
patterns of phenology change across the season," authors note Itter
says the team expected to see differences in breeding period linked
to distinct ecological zones across a latitudinal gradient in Finland,
but found instead that "ecological zone didn't seem to matter, changes
in the beginning, duration and end of breeding did not vary strongly by ecological zone for a given species." This work was supported by the
Jane and Aatos Erkko Foundation through the RCEC at the University of
Helsinki and the Academy of Finland.


========================================================================== Story Source: Materials provided by
University_of_Massachusetts_Amherst. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Maria H. Ha"llfors, Laura H. Anta~o, Malcolm Itter, Aleksi
Lehikoinen,
Tanja Lindholm, Tomas Roslin, Marjo Saastamoinen. Shifts in
timing and duration of breeding for 73 boreal bird species over
four decades.

Proceedings of the National Academy of Sciences, 2020; 201913579
DOI: 10.1073/pnas.1913579117 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200723143642.htm

--- up 1 week, 1 day, 1 hour, 55 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)