Afromontane understory birds increase in body size over four decades

Of the myriad responses to climate change, an emerging trend is the widespread decrease in animal body size with warming temperatures. Birds, in particular, have been shown to be decreasing in body size in several areas – most notably the Amazon Basin and temperate North America – but trends in much of the world remain unexplored. Here, we analyze temporal trends in and climatic associations of body mass for 42 resident bird species over 36 years in the Usambara Mountains of Tanzania, a tropical montane global biodiversity hotspot. In addition, we assess trends in wing length and mass:wing ratio over 21 years. Finally, we examine whether species-specific trends in body mass are related to average body size or to trends in apparent survival. Overall, species’ average body mass in the Usambara Mountains increased by 0.023 g/decade, amounting to increases of 4.1% over 36 years. These long-term shifts in body mass were strongly and positively associated with annual mean temperature but show..., , , # Body mass of Tanzanian birds

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This dataset comprises the body mass and wing length measurements of 42 Afromontane bird species taken over 36 years in the Usambara Mountains of Tanzania.

## Description of the Data and file structure

The dataset comprises eight columns.

* A: an \"order\" column to return data to the original ordering.
* B: the initials of the bander who weighed the bird.
* C: binary location, either EU (East Usambaras) or WU (West Usambaras).
* D: the year, starting at 0=1987.
* E: the site; redundant as 16=EU and 23=WU.
* F: species, based Clements taxonomy.
* G: bird weight (g).
* H: wing length (cm).