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Abstract Developing conservation and recovery strategies for Nearctic–Neotropical migratory songbirds requires key research because population-limiting factors remain unknown for many species. In particular, the stationary nonbreeding period (sometimes referred to as overwintering) encompasses 6–8 months of the full annual cycle. We conducted a systematic review to assess what is known about the factors that influence individual-level performance (i.e., fitness proxies or indicators of self-maintenance) of Nearctic–Neotropical migratory songbirds during the stationary nonbreeding period. We focused on the metrics of apparent survival, persistence, and body condition (mass-related) indices. We found that 51 of 125 migratory Passeriformes species’ performance has been studied in 57 studies during the nonbreeding period. However, most species appear in only one study; thus, knowledge is skewed toward 3 species appearing in ≥ 10 studies. Body condition indices were the most studied group of metrics and apparent survival was the least studied. Habitat type, food availability, and precipitation were studied much more than other drivers, such as disease and predation. The most studied driver of nonbreeding performance was habitat type. Evidence was found among these studies that suggest that natural habitat types, wetter habitats or precipitation, and high availability of food may positively influence body condition, apparent survival, and persistence. Significant knowledge gaps remain that, if filled, could inform conservation strategies, especially for 59.2% of Passeriformes that are Nearctic–Neotropical migratory species and for areas of the nonbreeding range. 

Abstract A prominent challenge for managing migratory species is the development of conservation plans that accommodate spatiotemporally varying distributions throughout the year. Migratory networks are spatially‐explicit models that incorporate migratory assignment and seasonal abundance data to define patterns of connectivity between stages of the annual cycle. These models are particularly useful for widespread application because different types of migratory data can be used to quantify individual and population‐level movement across the annual cycle of migratory species. While there are clear benefits of combining migratory assignment and abundance data for the development of conservation strategies, there is a concurrent need for corresponding user‐friendly software to facilitate the integration of these data for conservation.Here, we presentmignette(migratory network tools ensemble), an R package for developing migratory network models to estimate network connectivity among migratory populations. We demonstrate the functionality ofmignettewith three empirical examples that highlight the use of different types of tracking data for migratory assignment.mignettefacilitates the modelling of migratory networks by providing R functions to: (1) define breeding and nonbreeding nodes, (2) assemble abundance and assignment data and (3) model the migratory network. Additionally,mignetteprovides R functions to visualize modelled migratory networks.With increasing availability of migratory assignment and abundance data,mignetterepresents a valuable tool for developing effective conservation strategies for migratory species. 

Honduras cuenta con 349,510 hectáreas cultivadas con café Coffea arabica, que son en su mayoría cultivos tradicionales (café sombra y café sol), y en menor escala cultivos con sistema Dosel Abierto Integrado (DAI). El sistema de café DAI consiste en plantaciones de café rodeadas por bosque en una proporción ≥ 1:1, lo que permite la preservación y la restauración de ecosistemas nativos. El objetivo de nuestra investigación fue evaluar el sistema DAI en cultivos de café como una alternativa de conservación para las aves migratorias neártico-neotropicales y aves residentes. Evaluamos características ecológicas, como la riqueza y abundancia de especies, entre los meses de noviembre de 2018 a abril de 2019. Establecimos 75 puntos de conteo de radio fijo en una zona cafetalera del departamento de Yoro, Honduras. Estadísticamente no registramos diferencias significativas en la riqueza de aves migratorias entre los sistemas de bosque, café DAI y cultivos de café tradicionales. Sin embargo, la riqueza de especies dependientes de bosque fue mayor en los sistema bosque y cultivos de café DAI que en cultivos tradicionales. Además, algunas especies dependientes de bosque, como Myioborus miniatus y Mionectes oleagineus, fueron más abundantes (P < 0.05) en bosque y cultivos de café DAI que en cultivos de café tradicionales. Nuestros resultados se suman a los reportados en Costa Rica, en donde se introdujo este agroecosistema de cultivo de café, en los que se indica que el café DAI puede ser una alternativa para la conservación de aves migratorias y residentes, en particular para especies dependientes de bosque. 

The preference-performance hypothesis explains host specificity in phytophagous insects, positing that host plants chosen by adults confer the greatest larval fitness. However, adults sometimes oviposit on plants supporting low larval success because the components of host specificity (adult preference, plant palatability, and larval survival) are non-binary and not necessarily correlated. Palatability (willingness to eat) is governed by chemical cues and physical barriers such as trichomes, while survival (ability to complete development) depends upon nutrition and toxicity. Absence of a correlation between the components of host specificity results in low-performance hosts supporting limited larval development. Most studies of specificity focus on oviposition behavior leaving the importance and basis of palatability and survival under-explored. We conducted a comprehensive review of 127 plant species that have been claimed or tested to be hosts for the monarch butterfly Danaus plexippus to classify them as non-hosts, low performance, or high performance. We performed a meta-analysis to test if performance status could be explained by properties of neurotoxic cardenolides or trichome density. We also conducted a no-choice larval feeding experiment to identify causes of low performance. We identified 34 high performance, 42 low performance, 33 non-hosts, and 18 species with unsubstantiated claims. Mean cardenolide concentration was greater in high- than low-performance hosts and a significant predictor of host status, suggesting possible evolutionary trade-offs in monarch specialization. Other cardenolide properties and trichome density were not significant predictors of host status. In the experiment, we found, of the 62% of larvae that attempted to eat low-performance hosts, only 3.5% survived to adult compared to 85% of those on the high-performance host, demonstrating that multiple factors affect larval host plant specificity. Our study is the first to classify all known host plants for monarchs and has conservation implications for this threatened species.