Agave distribution and floral display influence foraging rates of an endangered pollinating bat and implications for conservation.

Wildlife conservation involves making management decisions with incomplete knowledge of ecological relationships. Efforts to augment foraging resources for the endangered Mexican long-nosed bat (Leptonycteris nivalis) are progressing despite limited knowledge about the species' foraging behavior and requirements. This study aimed to understand L. nivalis responses to floral resource availability, focusing on individual agave- and local-scale characteristics influencing visitation rates to flowering agaves. We observed bat visitation at 62 flowering agaves around two roosts in northeast Mexico on 46 nights in the summers of 2017 and 2018. We found visitation rate had positive relationships with two agave-scale characteristics: the number of umbels with open flowers and the lower vertical position on the stalk of those umbels (i.e., earlier phenological stages of flowering). However, these factors exhibited strong negative interaction: with few umbels with open flowers, the position of flowering umbels had little effect on visitation rate, but when umbels with open flowers were abundant, visitation rate was more strongly related to the lower flowering umbel position. We also found relationships between visitation rate and two local-scale characteristics: negative for the density of flowering conspecifics within 30 m of the focal agave and positive for the density of dead standing agave stalks within 30 m. Our findings suggest opportunities to augment foraging resources for L. nivalis in ways that are consistent with their foraging behavior, including: increasing the supply of simultaneously blooming flowers by planting agave species that tend to have more umbels with simultaneously open flowers; planting multiple species of agaves with different flowering times to increase the availability of agaves with open flowers on lower-positioned umbels throughout the period when bats are present in the region; planting agaves in clusters; and keeping dead standing agave stalks on the landscape. Our study points to useful management strategies that can be implemented and monitored as part of an adaptive management approach to aid in conservation efforts.

Impacts of land cover change on the plant resources of an endangered pollinator.

One of the key drivers of pollinator declines is land cover change. We documented for the first time the impacts of over three decades of land cover change in Mexico on the plant resources of an endangered migratory pollinator, the Mexican long-nosed bat, Leptonycteris nivalis. This species is considered endangered under national and international criteria due to population declines over 50% in the past 10 years. Pregnant females of this bat species migrate every year following the blooms of Agave spp. from central Mexico to the southern United States; moving pollen over its 1,200 km long migratory corridor and pollinating distant populations of Agave spp. Increases in human populations density and agricultural expansion may be reducing agave habitat over time. The objective of our study is to understand the land cover change trends in the northern range of the bat and identify potential fragmentation patterns in the region. We analyzed changes that occurred in three vegetation types where agaves are found in five time periods 1985, 1993, 2002, 2007 and 2011. The area of the three vegetation types selected was reduced by using only the overlap with potential agave habitat created with ecological niche modeling algorithms to obtain the available agave habitat. We then calculated fragmentation metrics for each period. We found a significant portion of habitat lost mainly due to expansion in agriculture. The total number of patches increased after 1985. Only 9% of the available agave habitat in 2011 is inside the limits of protected areas. We recommend restoring agave populations in depleted areas to help prevent soil erosion and provide multiple socio-economic benefits for the region in the short term, and, in the long-term maintaining foraging resources for nectar-feeding bats.

Current knowledge on Mexican tardigrades with a description of Milnesium cassandrae sp. nov. (Eutardigrada: Milnesiidae) and discussion on the taxonomic value of dorsal pseudoplates in the genus Milnesium Doyère, 1840.

Mexico is a megadiverse country, however its tardigrade fauna is poorly known and to date 44 species have been reported from this region. In the present paper, an update of the reported Mexican tardigrades is presented, increasing the number of recorded tardigrades to 55 species (11 new records). Moreover, we describe Milnesium cassandrae sp. nov. from State of Nuevo León in northern Mexico. The new species is most similar to Mil. krzysztofi Kaczmarek Michalczyk, 2007 and Mil. beasleyi Kaczmarek, Jakubowska Michalczyk, 2012, but it differs from them mainly by details of the dorsal sculpture and some morphometric characters. We also discuss the taxonomic value of a recently described feature, 'pseudoplates', for differentiating the taxa within the genus Milnesium Doyère, 1840. [Zoobank URL: urn:lsid:zoobank.org:act:0684AE18-0510-4F7B-B75D-AE5177FBF2A2].