Composition of the Montezuma Quail’s Diet in Arizona, New Mexico, and Texas

The Montezuma quail (Cyrtonyx montezumae) is a popular game bird and an indicator species of oak-pine savannas in the northern part of its range. In Arizona and New Mexico, USA, robust populations allow for a hunting season from mid-November through mid-February. However, there is no open hunting season for this quail in Texas, USA. Data on the Montezuma quail’s diet can provide new information and improve management of the species. Our objective was to analyze the diet composition of the Montezuma quail in Arizona, New Mexico, and Texas. Specimens were collected by hunters in Arizona and New Mexico during 2016–2020 seasons and by researchers during 2018–2020 winter and spring seasons in Texas. We estimated the diet composition by macrohistological analysis of the collected quail crops. We found a high variety of food items: 178 items or morphospecies in crops (n = 175), from which 110 and 66 items were of plant and animal origin, respectively, and 2 unidentified items. We found an average (± standard error) of 5.89 ± 0.42 items/crop (range = 0–22) in Arizona (n = 107) samples, 4.15 ± 0.99 items/crop (range = 1–13) in New Mexico (n = 13), and 4.38 ± 0.40 items/crop (range = 1–12) in Texas (n = 55). Winter diet of Montezuma quail in Arizona was mainly represented by bulbs of Oxalis spp. (35.22% of dry weight), bulbs and rhizomes of Cyperus spp. (30.92%), acorns (Quercus spp.; 7.17%), and tepari beans (Phaseolus acutifolius; 6.50%). Winter diet in New Mexico consisted mainly of bulbs of Cyperus spp. (64.13%), beans of Macroptilium spp. (15.82%), and Panicum hallii grains (10.11%). In Texas, winter diet consisted mostly of rhizomes and bulbs of Cyperus spp. (28.17%), Rhynchosia senna beans (22.49%), P. hallii grains (19.54%), Allium wild onions (8.58%), and Cylindropuntia imbricata seeds (4.16%). The Montezuma quail’s spring diet in Texas consisted mainly of rhizomes and bulbs of Cyperus spp. (61.64%) and bulbs of Oxalis spp. (19.46%). The Montezuma quail diet changes in composition and proportion according to the site and season, but bulbs and rhizomes of Cyperus spp. are the predominant food items in all 3 states. This work provides novel information about the winter and spring diet of Montezuma quail in Texas. Information about Montezuma quail diet at several temporal and geographic scales will prove to be highly relevant to implement better management and conservation strategies in the northern edge of the species’ range

Tropical tree growth driven by dry-season climate variability

Interannual variability in the global land carbon sink is strongly related to variations in tropical temperature and rainfall. This association suggests an important role for moisture-driven fluctuations in tropical vegetation productivity, but empirical evidence to quantify the responsible ecological processes is missing. Such evidence can be obtained from tree-ring data that quantify variability in a major vegetation productivity component: woody biomass growth. Here we compile a pantropical tree-ring network to show that annual woody biomass growth increases primarily with dry-season precipitation and decreases with dry-season maximum temperature. The strength of these dry-season climate responses varies among sites, as reflected in four robust and distinct climate response groups of tropical tree growth derived from clustering. Using cluster and regression analyses, we find that dry-season climate responses are amplified in regions that are drier, hotter and more climatically variable. These amplification patterns suggest that projected global warming will probably aggravate drought-induced declines in annual tropical vegetation productivity. Our study reveals a previously underappreciated role of dry-season climate variability in driving the dynamics of tropical vegetation productivity and consequently in influencing the land carbon sink

Tropical tree growth driven by dry-season climate variability

Interannual variability in the global land carbon sink is strongly related to variations in tropical temperature and rainfall. This association suggests an important role for moisture-driven fluctuations in tropical vegetation productivity, but empirical evidence to quantify the responsible ecological processes is missing. Such evidence can be obtained from tree-ring data that quantify variability in a major vegetation productivity component: woody biomass growth. Here we compile a pantropical tree-ring network to show that annual woody biomass growth increases primarily with dry-season precipitation and decreases with dry-season maximum temperature. The strength of these dry-season climate responses varies among sites, as reflected in four robust and distinct climate response groups of tropical tree growth derived from clustering. Using cluster and regression analyses, we find that dry-season climate responses are amplified in regions that are drier, hotter and more climatically variable. These amplification patterns suggest that projected global warming will probably aggravate drought-induced declines in annual tropical vegetation productivity. Our study reveals a previously underappreciated role of dry-season climate variability in driving the dynamics of tropical vegetation productivity and consequently in influencing the land carbon sink