Nesting Activity Research Articles

Nesting activity of cavity‐nesting bees and wasps is lower in small‐scale apple orchards compared to nearby semi‐natural habitats

AbstractCommercially reared cavity‐nesting bees have been studied mainly in large, intensively managed orchards. However, knowledge on wild cavity‐nesting bee and wasp communities and their potential limitations in smaller orchards remain insufficient. We compared the colonization rate of trapnests, nesting success, parasitism and response to flower resources of cavity‐nesting bees and wasps between apple orchards and nearby semi‐natural habitats (SNHs). Trapnests were placed in orchards and neighbouring SNHs. Colonization dynamics were studied and herbaceous flower resources were estimated. Furthermore, nest and brood cell quantity, number of alive offspring and nest parasitism rate were assessed. We found a higher colonization rate in the SNHs than in the orchards. Both bees and wasps made more nests, completed more brood cells and had a higher number of alive offspring in the SNHs. The number of bee nests in the orchards showed a positive correlation with the species richness of the flowering plants. The nest parasitism of wasps was higher in the SNHs. Apple orchards in the studied small‐scale system were generally less colonized by cavity‐nesting hymenopterans than nearby SNHs that can be important reservoirs of these ecosystem service provider hymenopterans. Our results highlight the importance of diverse flowering herbaceous vegetation in the understory that increased the number of bee nests in orchards and that could have a positive effect on the nesting activity of the bee species active in summer. Therefore, management practices that support flowering plant species in the understory vegetation are highly recommended in such orchards.

Green Turtle (Chelonia mydas) Nesting Underscores the Importance of Protected Areas in the Northwestern Gulf of Mexico

Knowledge of the spatial and temporal distribution of green sea turtle (Chelonia mydas) nesting is crucial for management of this species. Limited data exist on the nesting patterns of green turtles along the northwestern Gulf of Mexico (GOM) coast. From 1987 to 2019, 211 green turtle nesting activities were documented on the Texas coast, including 111 confirmed nests and 100 non-nesting emergences. Of the 111 nests, 99 were located on North Padre Island (97 at Padre Island National Seashore (PAIS), 2 north of PAIS) and 12 on South Padre Island (6 within the Laguna Atascosa or Lower Rio Grande Valley National Wildlife Refuges (NWR), 6 outside of a NWR). Of the 100 non-nesting emergences, 75 were on North Padre Island (70 at PAIS, 5 north of PAIS), 21 on South Padre Island (9 within a NWR, 12 outside of a NWR), 1 on Boca Chica Beach, 2 on San Jose Island, and 1 on Mustang Island. Nearly all of the nests (92.8%) and most of the non-nesting emergences (79.0%) were on property protected by the U.S. Department of the Interior as PAIS or a NWR, and confirmed nest density was largest at PAIS, highlighting the importance of these federally protected lands as nesting habitat for this threatened species. Of the 111 located nests, 8 were predated. Mean hatching success of the 103 non-predated nests was 77.4%, and 9,475 hatchlings were released from the predated and non-predated nests. The largest annual number of green turtle nests documented was 29 in 2017. Nesting appeared to increase since 2010, but at a much lower rate than at other GOM nesting beaches. To aid with recovery, efforts should be undertaken to monitor long-term nesting trends, protect nesting turtles and nests, and investigate potential causes for the slower recovery in Texas. Additionally, the genetic structure of the population that nests in Texas should be determined to reveal if the population warrants recognition as a unique management unit, or if it is part of a broader unit that is a shared nesting resource with Mexico which is already being considered as a unique management unit.

Observations on breeding behaviour of a pair of endangered Egyptian Vultures Neophron percnopterus (Linnaeus, 1758) over three breeding seasons in the plains of Punjab, India

The present study has been conducted to document information on breeding behaviour of Egyptian Vultures Neophrons percnopterus from Punjab. This study is based on 688 hours of video records documenting breeding behaviour of a pair of endangered Egyptian Vultures Neophrons percnopterus occupying the same nesting site over three consecutive breeding seasons from 2015 to 2017. The site is located in the hollow of a ventilation window of the Space Observatory in Punjabi University, Patiala, Punjab. During the third breeding period (February to August 2017), the nest activity has been extensively video-recorded in egg laying and incubation period, and chick rearing period using a Dome CCTV Camera. Both parents participated in nest building, and of the total recorded incubation time of 339.39h over 23 days the nest was attended for 199.35 and 139.46h by the female and male respectively, and unattended for 0.58h. The incubation period was 42 to 43 days, and the egg laying/hatching intervals between eggs/chicks was five days. A total of six young ones hatched and fledged from three broods of two eggs each. All chicks survived to fledging and no mortality or siblicide of younger chick occurred due to aggression/starvation by elder chick. The high fledging success rate indicates a healthy habitat and food source in the nesting area.

Association of empty nest and group activity with cognitive impairment in Chinese older adults: A cross-sectional study

ObjectivesThis study explored the associations of empty nest and group activity with cognitive impairment in Chinese older adults. Materials and methodsData were analyzed from 10,349 participants of the second-round survey database of the Zhejiang Ageing and Health Cohort Study aged 60 years and over. Cognitive impairment was assessed by the Mini-Mental State Examination questionnaire. Logistic regression models controlled for an extensive range of potential confounders were generated to examine the associations of empty nest and group activity with cognitive impairment. ResultsNo association was found between empty nest and cognitive impairment in total participants. However, when stratified by sex, empty nest women were less likely to have cognitive impairment than non-empty nest women, odds ratio (OR) (95 % confidence interval [CI]) (0.846; 0.721, 0.993). Elders who participated in group activities showed significantly lower odds of cognitive impairment than those who never attended group activities, (0.811; 0.723, 0.910). This association remained significant in the 60–69-years group when further stratified by age, with an OR (95 % CI) of 0.616 (0.514, 0.739). ConclusionsEmpty nesters were not vulnerable to poor cognitive function. Participation in group activities was significantly associated with lower odds of cognitive impairment. Prospective studies are needed to assess the effect of empty nest and group activity on the risk of cognitive impairment.

First Record of Grasshopper Sparrow (Ammodramus savannarum) Breeding in the Grasslands of Durango, México, with Notes on Nesting Sites and Habitat

Grassland birds are one of the most rapidly declining bird guilds in North America, likely as a result of the loss and degradation of native grasslands. The Grasshopper Sparrow (Ammodramus savannarum), a migratory grassland bird of North America, relies on dense, relatively tall grasses with low shrub densities. In Mexico, 4 subspecies of A. savannarum have been reported; however, the distribution of the species in the summer is poorly known, with only 2 records from northern Mexico within the states of Zacatecas and Chihuahua. Here, we report on the presence and nesting activity of A. savannarum in the Cuchillas de la Zarca Grassland Priority Conservation Area in northern Durango, Mexico. We describe the morphometric characteristics of the birds captured, speculate on subspecies designation, and report on characteristics within the territories of singing males and habitat at the nest site. The Cuchillas de la Zarca region is one of the most important sites for wintering grassland birds, particularly A. savannarum, but faces threats such as shrub encroachment caused by poor grazing management. Here we present evidence that this region also provides breeding habitat for the Grasshopper Sparrow, further highlighting its value as a priority area for the conservation of grassland birds.

The status of the red mason bee in the orchards of Ankara and Çankırı Provinces, Turkey

Research on the red mason bee, Osmia bicornis (L., 1758) (Hymenoptera: Megachilidae), which is an important pollinator particularly for stone fruits, in Turkey is limited to the last decade. After the first report in sweet cherry orchards of Afyonkarahisar, this study aimed to determine the presence and the density of the red mason bee and to collect data on its nesting biology between 2014 and 2016 in the mixed orchards of Ankara and Çankırı Provinces. Although the red mason bee was detected in almost all orchards sampled using the Malaise trap, the nesting activity was recorded in only four orchards in 2014 and 2015. Reeds with an inner diameter of 6-9 mm and a length of 15-25 cm were used as the artificial trap-nests. It was determined that the percentage of the nesting success varies between 6 and 48%. The cocoons that originated from the nests were placed in the incubator to stimulate diapause. Then, the temperature of the incubator was gradually increased to complete the life cycle of the species with starting the bud stage of stone fruits in early spring. Consequently, the emergence rates of the adults from the 135 cocoons collected in 2014 were 36 to 95%. It was not recorded the adult emergence from any of the 143 cocoons obtained from the dissections of the nests in 2015. The sex ratios, both between orchards and from 2014 to 2015 in the same orchard ranged between 1:1.5-1:4 (♀:♂). The results are discussed based on stress conditions such as weather, limited pollen and nectar sources and insecticide application.

Conditional female strategies influence hatching success in a communally nesting iguana.

The decision of females to nest communally has important consequences for reproductive success. While often associated with reduced energetic expenditure, conspecific aggregations also expose females and offspring to conspecific aggression, exploitation, and infanticide. Intrasexual competition pressures are expected to favor the evolution of conditional strategies, which could be based on simple decision rules (i.e., availability of nesting sites and synchronicity with conspecifics) or on a focal individual's condition or status (i.e., body size). Oviparous reptiles that reproduce seasonally and provide limited to no postnatal care provide ideal systems for disentangling social factors that influence different female reproductive tactics from those present in offspring‐rearing environments. In this study, we investigated whether nesting strategies in a West Indian rock iguana, Cyclura nubila caymanensis, vary conditionally with reproductive timing or body size, and evaluated consequences for nesting success. Nesting surveys were conducted on Little Cayman, Cayman Islands, British West Indies for four consecutive years. Use of high‐density nesting sites was increasingly favored up to seasonal nesting activity peaks, after which nesting was generally restricted to low‐density nesting areas. Although larger females were not more likely than smaller females to nest in high‐density areas, larger females nested earlier and gained access to priority oviposition sites. Smaller females constructed nests later in the season, apparently foregoing investment in extended nest defense. Late‐season nests were also constructed at shallower depths and exhibited shorter incubation periods. While nest depth and incubation length had significant effects on reproductive outcomes, so did local nest densities. Higher densities were associated with significant declines in hatching success, with up to 20% of egg‐filled nests experiencing later intrusion by a conspecific. Despite these risks, nests in high‐density areas were significantly more successful than elsewhere due to the benefits of greater chamber depths and longer incubation times. These results imply that communal nest sites convey honest signals of habitat quality, but that gaining and defending priority oviposition sites requires competitive ability.

Caretta caretta nesting activity on Akumal Beaches, Mexico

Mexico has made substantial contributions to marine turtle protection and conservation, especially since 1990. Several conservation projects entail monitoring efforts to recover nesting territories for marine turtles. The Sea Turtle Protection Program of Akumal, in the Mexican state of Quintana Roo, was created in 1993 and was developed by the Akumal Ecological Center. This paper provides the nesting ecology parameters for Caretta caretta over a protection period of 24 years (1995–2018). A well-defined nesting peak was observed in June, with a nesting success rate of 75.2 ± 23.0%. Nesting females showed a mean curved carapace length of 99.0 ± 5.6 cm. The mean clutch size was 108.6 ± 24.6 eggs, with variation among years. The mean incubation period was 57.2 ± 6.2 days. The hatching and emergence success rates were 87.2 ± 16.9% and 78.8 ± 24.4%, respectively. For the 926 tagged females that returned, the remigration interval peaked at 726 days, with a 12-day inter-nesting period. The results show not only the recovery of the nesting population over time but also a decrease in female size; we postulate that this decrease is due to the recruitment of young females, which has been increasingly pronounced since 2010. Hence, the Akumal rookery plays an important role in its corresponding regional management unit (Atlantic Northwest).

Population Status and Nesting Activity of White-Rumped Vulture Gyps bengalensis in Kotli District, Azad Jammu and Kashmir, Pakistan

White-rumped Vulture Gyps bengalensis colonies are expanding in some areas of their range after a catastrophic decline, yet in other areas population status and ecology remain poorly known. In the current study, we documented the first-ever monitoring of population size and nesting activity of the White-rumped Vulture using the road transect method in Kotli District, in Azad Jammu and Kashmir. Covering a 9.09 km road transect we found nine colonies, six of which had a total of 52 active nests (a mean of 5.8±5.6 nests per colony). The nine colonies contained a population of 191 vultures (a minimum of n=7, to a maximum of n=50 with a mean of 21.2±15 individuals per colony). Nests were on Chir Pine trees Pinus roxburghii at an average height of 20.8±1.6 meters from the ground. Most of the nests were near running water sources and roads. Vultures were found at waste from slaughterhouses, livestock carcasses, road-killed wildlife and street dogs, which appear to be their main sources of food. Forest fire could be detrimental to the species' population. Monitoring on an annual basis is needed in order to understand the population trend of the White-rumped Vultures in the area.

Nesting biology of Megachile (Eutricharea) studiosa Bingham, a leafcutter bee

Investigations on nesting biology of Megachile (Eutricharea) studiosa carried out at Pantnagar (India), revealed that this Megachile species is a leafcutter bee that nests in soil and also in trap nests having tunnel with diameter of 4.79 ± 0.24 mm during summer. The female invested an active time of 49.42 ± 4.24 h to complete its nesting activity in 6–7 days, maximum quantum of time (61.28%) being spent in provisioning the brood cells. The female made 1–6 brood cells in a nest and used leaf pieces of three different sizes to construct a single cell. In their natural habitat, the male progeny had development period of 22.29 ± 1.38 days while the female bees emerged in 29 ± 1 days during May–June at an ambient mean maximum temperature between 33.2 and 38.9 °C. The data on detailed nesting activity, nest structure, plants providing nesting material and larval food presented in this communication is the first report on Megachile (Eutricharea) studiosa Bingham which would help in understanding the ecology, behavior, and role of this leafcutter bee in biodiversity pool.

DIURNAL ACTIVITY PATTERN OF A PAIR OF BREEDING NORTHERN PYGMY-OWLS

In 2012, we explored the activity pattern of a pair of breeding Northern Pygmy-Owls based on 15 d (and 15 nights) of video monitoring of the nest-cavity entrance during the nestling period. Video monitoring ended after all 6 owlets had left the nest. All instances of nest activity (n= 288) occurred during the daylight period from 1 h before sunrise to 1 h after sunset, so the pair was not nocturnal. Most of the activity (60%) occurred during the diurnal period (1 h after sunrise to 1 h before sunset), and the rest was in the crepuscular period (the first and last 2 h of daylight). Prey type factored heavily into the frequency of activity at certain times of day, and on certain days during the nestling period. Activity during the diurnal period was dominated by the combination of vertebrate prey deliveries (80% of diurnal activity) and enticements of young from the nest (14% of diurnal activity). In contrast, activity during the crepuscular period was dominated by insect prey deliveries (60% of crepuscular activity). Overnight nest attendance activity, arriving and departing the nest to tend young through the night, accounted for 11% of crepuscular activity. For the entire 15-d monitoring period, deliveries of vertebrate prey made up 60% of all activity. The frequency of daily vertebrate prey deliveries was relatively similar for the first 10 full days of monitoring (range 9 to 13 deliveries), then peaked 3 to 4 d prior to fledging (range 15 to 20 deliveries) before declining on the last 2 d of the period, when deliveries of moths and enticement activity increased. We concluded that the pair's activity during the nestling period was consistent with a diurnal activity pattern. We encourage other researchers to refine the meanings of the terms diurnal and crepuscular and clarify how those terms should be used to define the primary activity pattern of a species.

Direct and indirect effects of regional and local climatic factors on trophic interactions in the Arctic tundra

Climate change can impact ecosystems by reshaping the dynamics of resource exploitation for predators and their prey. Alterations of these pathways could be especially intense in ecosystems characterized by a simple trophic structure and rapid warming trends, such as in the Arctic. However, quantifying the multiple direct and indirect pathways through which climate change is likely to alter trophic interactions and their relative strength remains a challenge. Here, we aim to identify direct and indirect causal mechanisms driven by climate affecting predator-prey interactions of species sharing a tundra food web. We based our study on relationships between one Arctic predator (Arctic fox) and its two main prey - lemmings (preferred prey) and snow geese (alternate prey) - which are exposed to variable local and regional climatic factors across years. We used a combination of models mapping multiple causal links among key variables derived from a long-term dataset (21years). We obtained several possible scenarios linking regional climate factors (Arctic oscillations) and local temperature and precipitation to the breeding of species. Our results suggest that both regional and local climate factors have direct and indirect impacts on the breeding of foxes and geese. Local climate showed a positive causal link with goose nesting success, while both regional and local climate displayed contrasted effects on the proportion of fox breeding. We found no impact of climate on lemming abundance. We observed positive relationships between lemming, fox and goose reproduction highlighting numerical and functional responses of fox to the variability of lemming abundance. Our study measures causal links and strength of interactions in a food web, quantifying both numerical response of a predator and apparent interactions between its two main prey. These results improve our understanding of the complex effects of climate on predator-prey interactions and our capacity to anticipate food web response to ongoing climate change.

Habitat Preference and Phenology of Nest Seeking and Foraging Spring Bumble Bee Queens in Northeastern North America (Hymenoptera: Apidae: Bombus)

Bumble bees are among the most abundant and important wild pollinators in North America. Spring nest establishment is a brief and vulnerable stage in the colony life cycle that is poorly understood. Bumble bee nesting activity in temperate North America has received little recent attention, and this knowledge gap is a barrier to conservation efforts. The aim of this study was to investigate the habitat use, nesting phenology, and key food plants of spring bumble bee queens. Through 108 nonlethal surveys of bumble bee queens in spring 2018, researchers observed 451 nest seeking and 555 foraging queens of nine species in Ohio, U.S.A. Spring queen activity began in mid-April and peaked in mid-May, although nest seekers were observed into late June. Nest seeking queens favored woody transitional habitats over open habitats. In accordance queen abundance and diversity increased with the proportion of forest in the surrounding landscape. The proportion of row crops and urban areas negatively influenced queen diversity and the number of nest seekers, respectively. Through a literature review, the earliest emergence dates for each species were compared for 12 datasets to establish an order of species emergence in northeastern North America. Forty-seven species of flowering plants were used by foraging queens. Highly visited food plants included both native and nonnatives(*): Lupinus perennis, Malus spp., Taraxacum officinale*, Lonicera spp.*, Lamium purpureum*, Glechoma hederacea*, Trifolium pratense*, and Mertensia virginica. Systematic field surveys are needed by state to document the timing of spring queen emergence and nesting activities to inform conservation efforts.

Use of passive radio frequency identification technologies to monitor nest usage in the northern carmine bee-eater (Merops n. nubicus).

The use of radio frequency identification (RFID) technology is common in animal-monitoring applications in the wild and in zoological and agricultural settings. RFID is used to track animals and to collect information about movements and other behaviors, as well as to automate or improve husbandry. Disney's Animal Kingdom® uses passive RFID technology to monitor nest usage by a breeding colony of northern carmine bee-eaters. We implemented RFID technologies in various equipment configurations, initially deploying low-frequency (LF) 125 kHz RFID and later changing to high-frequency (HF) 13.56 MHz RFID technology, to monitor breeding behavior in the flock. We installed antennas connected to RFID readers at the entrances of nest tunnels to detect RFID transponders attached to leg bands as birds entered and exited tunnels. Both LF-RFID and HF-RFID systems allowed the characterization of nest visitation, including the timing of nest activity, breeding pair formation, identification of egg-laying females, participation by nonresidents, and detection of nest disruptions. However, we collected a substantially larger volume of data using the increased bandwidth and polling speed inherent with HF-RFID, which permitted tag capture of multiple birds simultaneously and resulted in fewer missed nest visits in comparison to LF-RFID. Herein, we describe the evolution of the RFID setups used to monitor nest usage for more than 7 years, the types of data that can be gained using RFID at nests, and how we used these data to gain insights into carmine bee-eater breeding behavior and improve husbandry.

Protecting Species through Legislation: The Case of Sea Turtles

We evaluate the effectiveness of legislation in reducing the negative impacts of beachfront lighting on sea turtle nesting activity, one of the main threats to the species. To this end we construct a time varying index of ordinance effectiveness across Florida counties and combine this with loggerhead nesting data to create a panel data set covering a twenty‐six year period. Our econometric findings show that such legislation can significantly increase nesting activity, where current levels of protection result in an additional 34%. Using our estimates within a calibrated population model we also demonstrate that legislation can reduce the time to the animals’ extinction. Finally, when considering estimates of local willingness to pay for sea turtle preservation, we show that alternatively raising sea turtles in captivity under a head start program may be prohibitively expensive.

Observations on nesting activity, life cycle, and brood ball morphometry of the Bordered Dung Beetle Oniticellus cinctus (Fabricius, 1775) (Coleoptera: Scarabaeidae) under laboratory conditions

The nesting activity, life cycle, and brood ball morphometry of the dung beetle Oniticellus cinctus (Fabricius, 1775) (Coleoptera: Scarabaeidae) were studied under laboratory conditions for the first time in India. The females made a brood chamber within the dung mass provided, wherein they made brood balls to lay eggs. The life cycle includes egg, larva (three instars), pupa, and adult stages. The total duration for the development was about one month. The study found that there was a significant difference present in the brood ball diameter (except in the first and second instars) and brood ball weight (except in the second instar and pupa) of the six life cycle stages. It was also found that brood ball weight and diameter have a significant positive correlation as well as a linear relationship.

Is a small sea turtles rookery doomed to local extinction? Decreasing nesting trends at the Paria Gulf, Venezuela

AbstractSmall rookeries are rarely evaluated for marine turtles worldwide. Two species of sea turtles (Hawksbill, Eretmochelys imbricata; Leatherback, Dermochelys coriacea) nest on five main beaches of the northeast coast of the Paria Gulf in Venezuela. Population trends using generalized linear models at this rookery were assessed and compared with other small rookeries. Both species showed significant negative nesting trends: Nesting by critically endangered hawksbills decreased over nine seasons 2009–2017 (64–142 nests per year, General Linear Model Slope Value = −0.061; data pooled for five beaches); similarly, vulnerable leatherback nests decreased across the same period in the main beach Los Garzos (0–69 nests/year; GLMSV = −0.34). Besides human and natural predation of the nests, no significant environmental impacts affect the beaches except probably on Obispo Isthmus where a gas pipeline installation interrupted the nesting activity in 2014. Observed changes to the nesting trends in these small rookeries have a collective impact on broader conservation concerns for sea turtles in the region.

Host-parasitoid interactions between the solitary bee Centris analis (Apidae: Centridini) and conopid flies (Diptera: Conopidae).

Natural enemies are one of the main mortality factors in bees and wasps attacking either immature stages or adults of their hosts. Dipterans of the genus Physocephala (Diptera: Conopidae) are parasitoids that attack adult bees during their field activities, and the parasitoid larvae develop inside the host abdomen. However, little is known about the biology of these natural enemies and their interactions with their solitary bee hosts. This study is aimed at analyzing attacks by conopid flies in one of their hosts, the solitary bee species Centris analis (Apidae: Centridini), and the consequences in the nesting behavior of this bee species. Higher incidences of parasitism occurred during the hot/wet season, and seven fly species attacking C. analis were identified. Of the fifty-six females observed during their nesting activities, seven of them were parasitized. These females showed alterations in their nesting behavior, depositing extra oil on the plug of finished nests and building plugs in empty cavities. The behavioral changes observed in these females began during larval stage L1 of the parasitoid. In the last stages of parasitoid development (L3 PUP and pupa), the bees ceased their flight activities and entered cavities at the nesting site, remaining there until death.

Habitat-Use Patterns among Migrant and Resident Landbirds of Contrasting Dietary Habits in a Southern Mexican Wetland

The distribution of resident and migratory bird abundance across mangrove and marsh patches can produce dynamic and guild-specific habitat-use patterns. Using 32 consecutive months of point counts in a coastal landscape in Oaxaca, Mexico, we studied the annual cycle, non-breeding season (October to March) and breeding season (May to August) of terrestrial birds. For broad trophic guilds of plant-consumers and insectivores, we disclosed seasonal dynamics and assessed the spread of non-breeding season abundance across migratory habit categories and habitat types. To test for habitat-use patterns derived from hypotheses concerning specific trophic resources, we focused on subsets within trophic guilds: frugivores (plant-consumers that mainly eat fruit) and invertebrate gleaners (insectivores that mainly eat terrestrial leaf and stem invertebrates). Drawing on a resourcecentred dietary requirement hypothesis, we predicted lower abundance of migrant frugivores in mangrove, where palatable fruit availability was expected to be low and resident frugivores probably exploited invertebrates to feed nestlings. Based on the competition-oriented nest predation hypothesis, we anticipated a higher proportion of migrant invertebrate gleaners in marsh. We recorded migrant birds in every month of the year. For 20 plant-consumer species, the non-breeding season density was highest among residents in mangrove (> 5 individuals per hectare). For 46 insectivore species, densities were > 5 and > 9 individuals per hectare for migrants and residents, respectively. Comparable average abundances in trophic guilds suggested both migrant and resident species were equally important. For 14 frugivore species, a higher proportion of migrants in marsh (0.90) than mangrove (0.03) resulted from reciprocal between-habitat changes in migrant and resident abundances, as predicted by the dietary requirement hypothesis. For 22 invertebrate gleaners, proportions of migrants in mangrove (0.45) and marsh (0.55) were comparable, as were abundances. Contrary to the nest predation hypothesis, any between-habitat variation in invertebrate gleaner nesting activity did not markedly influence non-breeding season abundance. —Ruiz, M.D.M., Leon-Cortes, J.L., Enriquez, P.L., Garcia-Estrada, C. & Rangel Salazar, J.L. (2019). Habitat-use patterns among migrant and resident landbirds of contrasting dietary habits in a southern Mexican wetland. Ardeola, 66: 291-310.

Nesting Biology of Sympatric Species of Megachilidae Bees in a Conservation Area in Brazilian Atlantic Forest

Megachilidae bees are important pollinators in the Neotropical region, however information on the ecology and behavior of these species is still scarce. The objective of this study was to analyze the nesting biology of sympatric species in the União Biological Reserve, a remnant of Atlantic Forest in the southeastern Brazil. Our results indicated the occurrence of 17 species, representing significant richness compared to other areas in the Atlantic Forest. Five sympatric species built ¾ of all nests found and the architecture of their nests was studied including, for the first time, nests of a species of Megachile (Ptilosarus). The use of petals or leaf fragments in the construction of the nests was observed for species of Megachile (Chrysosarus), confirming previous data. The nesting activity period in the trap-nests occurred mainly in the rainy season, with different peaks among the species. The results indicate that the distinctive characteristics of the species, such as the type of material used in the nests, the dimensions of cavities, and the asynchronous nesting period, could be important for the niche differentiation of these sympatric species, allowing the maintenance and the survival of the most abundant Megachilidae populations in the area.