Reproductive phenology of blackbuck in Velavadar National Park, India

This data set comprises calving in blackbuck from 2000-2002 in Velavadar National Park, India to examine its breeding phenology in relation to body-condition, forage abundance and quality. Seasonality poses significant nutritional constraints for ungulates. Consequently, most ungulates time their energy-demanding events like calving and lactation to the availability of abundant and high-quality nutritional resources. We investigated the reproductive phenology of blackbuck, Antilope cervicapra, in relation to resource seasonality, in a semi-arid grassland in western India. We examined whether the body-condition of females, forage abundance, and forage quality influenced the timing of blackbuck reproduction. We also used a conceptual model to explore whether blackbuck use behavioural adaptations in maternal care as an adaptive strategy to buffer the high nutritional demands of lactation. Blackbuck showed biannual calving, which occurred before (pre-monsoon) and after the rains (post-monsoon). We found statistically significant relationships, albeit small effect sizes, of body-condition, forage abundance (biomass), and moisture content of grasses on the proportion of lactating females. The biannual reproductive phenology seems more complex than a simple relationship of reproduction with body-condition and optimal nutrition supply. In the conceptual model based on our data, we propose that blackbuck females shortened their lactation time and weaned their calves sooner during the pre-monsoon calving to coincide with a period of optimal food quality, thus, ensuring sufficient nutrition for both weanlings and allowing the females to regain body-reserves. Whereas, resource availability during the post-monsoon calving likely allowed females to invest in longer lactation, weaning the calves later, as compared to the pre-monsoon calving season. Thereby, blackbuck may be maintaining biannual calving and thus increase their lifetime reproductive output.This data set is from the article accepted and in production for online publication in Journal of Zoology with DOI 10.1111/jzo.12928.本数据集涵盖2000-2002年印度维拉瓦达尔国家公园内印度黑羚（blackbuck）的产仔记录，旨在探究其繁殖物候与体况、牧草丰度及品质之间的关联。季节周期性对有蹄类动物构成显著的营养限制，因此多数有蹄类会将产仔、泌乳这类高能量需求的事件，安排在营养资源丰富且优质的时段。本研究于印度西部的半干旱草原中，针对印度黑羚（Antilope cervicapra）的繁殖物候与资源季节周期性的关联展开调查，检验雌性体况、牧草丰度与牧草品质是否会影响印度黑羚的繁殖时机。我们还通过概念模型，探究印度黑羚是否会通过母育行为的适应性调整，作为缓冲泌乳高营养需求的适应性策略。研究发现，印度黑羚存在一年两次产仔的现象，分别发生在季风前与雨季过后。我们检测到雌性体况、牧草丰度（生物量）以及草本植物含水率与泌乳雌性比例之间存在统计学上的显著关联，尽管效应量较小。这种一年两次的繁殖物候模式，其背后机制似乎比繁殖与体况、最优营养供给间的简单关联更为复杂。基于本研究数据构建的概念模型显示，在季风前产仔的雌性印度黑羚会缩短泌乳时长、更早断奶幼崽，以匹配食物品质最优的时段，从而既能为断奶幼崽提供充足营养，也能让雌性自身恢复体储备。而相比季风前产仔期，季风后产仔期的资源可获得性更高，使得雌性能够延长泌乳时长、更晚断奶幼崽。借此，印度黑羚得以维持一年两次的产仔模式，进而提升其终身繁殖产出。本数据集源自已接收并即将在线发表于《动物学杂志（Journal of Zoology）》的论文，DOI为10.1111/jzo.12928。