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Avian Conservation and Ecology
Journal Prestige (SJR): 0.684

Citation Impact (citeScore): 2
Number of Followers: 17

This is an Open Access Journal

Open Access journal
ISSN (Print) 1712-6568
Published by Society of Canadian Ornithologists

[1 journal]

Long-distance dispersal patterns in the Cerulean Warbler: a case study
from Indiana
- Authors: Adele Mullie
  Abstract: Dispersal, defined as movement an individual makes from one breeding population to another, is a process that strongly influences the population dynamics of many animal species. Although dispersal across longer distances is believed to be a relatively uncommon phenomenon for most bird species, movements between populations drive numerous ecological processes, and understanding rates and directions of dispersal are especially important when considering species of conservation concern. The Cerulean Warbler (Setophaga cerulea) is a Nearctic-Neotropical songbird that breeds in mature forests of eastern and central North America and has experienced significant declines in recent decades largely due to habitat loss on the breeding grounds. Previous research suggests that Cerulean Warblers exhibit high rates of long-distance dispersal and that populations may be shifting away from the peripheral edges of its breeding range. The potential impacts of dispersal on reproductive success, however, remain unknown for this species. In this study, we used a long-term dataset (2013–2021) to investigate dispersal rates, age-related differences in dispersal, and effects of immigration on nest success in a population of Cerulean Warblers in south-central Indiana. To categorize birds as either immigrants or residents, we analyzed naturally occurring stable-hydrogen isotopes in tail feathers grown on the breeding grounds. We found an overall high rate (26.5%) of long-distance dispersal in this population, and the majority of these immigrants appeared to have originated from latitudes south of our study site. Additionally, our findings suggest that dispersal rates of juveniles and adults are very similar in this population, and that immigration appears to have no effect on reproductive success. This study contributes to our limited knowledge of the Cerulean Warblers' full annual cycle ecology, and our reported high dispersal rate and lack of effect of immigration on nest success have encouraging implications for the conservation of this declining species.The post Long-distance dispersal patterns in the Cerulean Warbler: a case study from Indiana first appeared on Avian Conservation and Ecology.
  PubDate: Thu, 18 May 2023 17:34:39 +000
Population trends and effects of local environmental factors on waterbirds
at Tanguar Haor freshwater wetland complex in northeast Bangladesh
- Authors: Adele Mullie
  Abstract: Analysis of long-term datasets on bird populations can be used to answer ecological and management questions that are useful for conservation. Tanguar Haor (9500 ha) is one of the major freshwater wetlands in Bangladesh and supports a large number of migratory and resident waterbirds. Because of its unique ecological and economic values, it is arguably the most notable wetland in the floodplains of northeast Bangladesh and in the region. This Ramsar site supports globally important populations of threatened waterbirds, such as the Baer’s Pochard Aythya baeri, Common Pochard Aythya ferina, Falcated Duck Mareca falcata, Ferruginous Duck Aythya nyroca, Oriental Darter Anhinga melanogaster, and Black-tailed Godwit Limosa limosa. Considering the international significance of this site, knowledge gaps on waterbird population trends, and key ecological factors, we conducted waterbird census between 2008 and 2021 to identify priority sites for conservation, population trends of resident and migratory waterbirds, and environmental factors that influence their abundances. We recorded a total of 69 species of waterbirds (maximum count of 166,788 individuals in 2013) and assessed population trends of 47 species. Of these, peak counts of 15 species exceeded the 1% threshold of their Asian-Australian Flyway population estimates. Most species (59%) showed a declining trend, including the critically endangered Baer’s Pochard and the vulnerable Common Pochard, and 16 species (41%) showed an increasing trend. Based on the abundance and species diversity, we have identified Chotainna beel and Lechuamara beel as conservation priority sites within the Haor complex and discuss key threats to these areas. We also offer evidence that adjusting water-level management to annual rainfall patterns could be a useful intervention for waterbird management. Involving local communities in conservation efforts by creating bird sanctuaries within the Haor complex will strengthen waterbird conservation in the country and along the East Asian-Australian Flyway.The post Population trends and effects of local environmental factors on waterbirds at Tanguar Haor freshwater wetland complex in northeast Bangladesh first appeared on Avian Conservation and Ecology.
  PubDate: Tue, 02 May 2023 16:05:06 +000
Metabarcoding fecal samples to investigate spatiotemporal variation in the
diet of the endangered Westland Petrel (Procellaria westlandica)
- Authors: Adele Mullie
  Abstract: As top predators, seabirds can be indirectly impacted by climate variability and commercial fishing activities through changes in marine communities. However, high mobility and foraging behavior enable seabirds to exploit prey distributed patchily in time and space. Despite this environmental adaptability, seabirds are the world’s most threatened birds and there is, therefore, an urge to acquire information about their ecological and foraging requirements through the study of their diet. Traditionally, the diet of seabirds is assessed through the morphological identification of prey remains in regurgitates. This sampling method is invasive for the bird and limited in terms of taxonomic resolution. However, the recent progress in DNA-based approaches is now providing a noninvasive means to more comprehensively and accurately characterize animal diets. We used a noninvasive metabarcoding approach to characterize the diet of the Westland Petrel (Procellaria westlandica), which is an endangered burrowing species, endemic to the South Island of New Zealand. We collected 99 fresh fecal samples in 2 different seasons and in 2 different subcolonies. Our aim was to describe the Westland Petrel’s diet and to investigate seasonal and spatial variations to their diet to understand the feeding requirements of this species. We also specifically investigated potential links with the New Zealand fishery industry to inform efficient conservation practices. Our noninvasive dietary DNA (dDNA) approach also highlighted significant differences in diet between seasons (incubation vs. chick-rearing season) and between sampling sites (two subcolonies 1.5 km apart). This suggests plasticity in the foraging strategy of the Westland Petrel. We found that amphipods were the most common prey, followed by cephalopods, and fish. Our findings could be the result of natural foraging behavior but also suggest a close link between the composition of prey items and New Zealand’s commercial fishing activities. In particular, the high abundance of amphipods could be the result of Westland Petrels feeding on discarded fisheries waste (fish guts). This close relationship to New Zealand’s fisheries may put stress on the resilience of the Westland Petrel. This valuable knowledge about Westland Petrel foraging needs is key to design efficient conservation plans for this iconic species. We illustrate how dDNA can inform the conservation of endangered or at-risk species that have elusive foraging behaviors.The post Metabarcoding fecal samples to investigate spatiotemporal variation in the diet of the endangered Westland Petrel (Procellaria westlandica) first appeared on Avian Conservation and Ecology.
  PubDate: Mon, 24 Apr 2023 16:02:10 +000
Diversity in selection patterns of five grassland songbirds in dry-mixed
grasslands of Alberta
- Authors: Adele Mullie
  Abstract: Declining grassland bird populations across North America continue to be a concern. Understanding local relationships between grassland bird abundance and vegetative and landscape characteristics will enable more prescriptive recommendations to be made to land managers. We used point count survey data collected by the MULTISAR (Multiple Species At Risk) program along with field measurements of habitat and landscape characteristics on 15 ranches in the Dry Mixed-grass Subregion in southern Alberta to improve our understandings of habitat relationships for five grassland bird species: Baird’s Sparrow (Centronyx bairdii), Sprague’s Pipit (Anthus spragueii), Thick-billed Longspur (Rhynchophanes mccownii), Chestnut-collared Longspur (Calcarius ornatus), and Grasshopper Sparrow (Ammodramus savannarum). We used generalized linear mixed models to examine the relationship between the predicted abundance of a species and covariates that represented vegetative structure (e.g., litter), management (e.g., range health), and anthropogenic features (e.g., energy development) of habitat site selection. Model results demonstrate four vegetation structure covariates were of most importance for predicting abundance, including litter, vegetation height, bare soil, and shrub cover. Quadratic relationships were found with litter amounts for the predicted abundance of Baird’s Sparrow, Chestnut-collared Longspur, and Grasshopper Sparrow. Contrastingly, higher amounts of litter reduced the predicted abundance of Thick-billed Longspur. The relationship of vegetation height was quadratic for Sprague’s Pipit and was positive for Baird’s Sparrow, but negative for Thick-billed Longspur. As bare soil percentage increased, the predicted abundance of Baird’s Sparrow and Chestnut-collared Longspur decreased, with Sprague’s Pipit showing a quadratic association. Negative relationships were found with increased amounts of shrub cover for Chestnut-collared Longspur, Sprague’s Pipit, and Thick-billed Longspur. Our results help to further understand individual grassland bird species’ habitat requirements, enabling us to provide land management recommendations for maintaining, improving, or creating the heterogenic environments needed for a variety of grassland birds in the Dry Mixed-grass Subregion.The post Diversity in selection patterns of five grassland songbirds in dry-mixed grasslands of Alberta first appeared on Avian Conservation and Ecology.
  PubDate: Thu, 20 Apr 2023 17:48:49 +000
Before-and-after evidence that urbanization contributes to the decline of
a migratory songbird
- Authors: Adele Mullie
  Abstract: Although urbanization is widely believed to be an increasing threat to biodiversity, drawing strong inferences about its effects on wildlife has been challenging because the state of a population prior to development is rarely known. The Wood Thrush (Hylocichla mustelina) is a steeply declining migratory songbird that breeds in North American temperate deciduous forests and winters in Central America. From 1987 to 2001, Wood Thrush abundance and daily nest survival were measured in 72 forest fragments across Waterloo Region, Ontario, Canada. Some of these fragments have since been surrounded by urbanization while others have remained rural. In 2020 and 2021, we reassessed Wood Thrush abundance and daily nest survival in these same fragments by replicating point count and nest monitoring protocols. Our results suggest that Wood Thrush have declined most steeply in fragments with development built within 1 km during the intervening 20-year period (-79% vs. only -57% elsewhere), although experiencing no decline in daily nest survival over the same time period, regardless of development. Our findings provide rare before-and-after evidence that urbanization near breeding habitat is contributing to a pronounced localized decline of a migratory songbird, likely by mechanisms unrelated to nest survival.The post Before-and-after evidence that urbanization contributes to the decline of a migratory songbird first appeared on Avian Conservation and Ecology.
  PubDate: Thu, 20 Apr 2023 15:32:42 +000
The growth rate of Black-tailed Gull chicks is negatively related to total
mercury of female parents on Kabushima (Kabu Island), Japan
- Authors: Adrian Williams
  Abstract: The mercury (Hg) contamination at high concentrations affects the physiological state and behavior of animals, however, the effects of low Hg exposure on avian breeding success and the impact on the growth of chicks that depend on feeding from their parents are unclear. We investigated the effects of maternal Hg concentrations on breeding success in a colony of Black-tailed Gulls (Larus crassirostris) breeding on Kabushima, northeastern Honshu, Japan, in 2018 and 2019. Total Hg concentrations in blood cells in females were 2.48 ug/g dry weight ± 0.55 (1.28–3.28) in 2018 and 2.42 ug/g dry weight ± 0.55 (1.87–3.29) in 2019. In our two-year field study, female parents did not differ in Hg concentrations between two years, but δ15Ns, i.e., the difference in diet, were significantly lower in 2019 than those in 2018. The difference in δ15Ns could be related to difference in fledging success between two years (90% and 40% in 2018 and 2019, respectively). However, the results of this study showed that Hg exposure was not significantly associated with clutch size, hatching success, or nest success in the two years with different diets and was not significantly associated with any reproductive parameters at δ15N. Hg exposure was significantly negatively correlated with chick weight gain (g/day), while blood Hg accumulation in female Black-tailed Gulls was below the threshold for direct effects on breeding success. However, there was no noticeable abnormal behavior when feeding the chicks at their Hg exposure levels, under the current level value. Although the breeding numbers of Black-tailed Gulls are not thought to be declining at colonies around Japan at the moment, Hg contamination may threaten their numbers in the future.The post The growth rate of Black-tailed Gull chicks is negatively related to total mercury of female parents on Kabushima (Kabu Island), Japan first appeared on Avian Conservation and Ecology.
  PubDate: Mon, 17 Apr 2023 17:05:13 +000
Patch-burn grazing provides resources for upland-nesting ducks
- Authors: Adele Mullie
  Abstract: Contemporary rangeland management has expanded from a focus on forage and livestock production to multi-use management practices that include concepts like biodiversity and natural disturbance regimes. Patch-burn grazing (PBG) has been promoted as a multi-use land management practice that can restore vegetation structural heterogeneity and subsequently increase diversity of higher trophic levels, such as grassland birds. However, little is known about how the diverse assemblage of upland-nesting ducks responds to disturbances like interacting fire and grazing within a PBG framework. PBG divides a pasture into equal proportions (i.e., patches) and burns an individual patch annually to reduce residual vegetation and attract livestock grazing. Upland-nesting ducks are generally thought to require dense vegetation structure associated with areas of low disturbance for nesting. However, prescribed fire and grazing are essential for the conservation and management of grasslands. PBG may negatively affect ducks in recently burned patches, but may also support ducks through the provisioning of greater structure in patches with greater year(s) since fire (YSF) and could be a viable management strategy to meet grassland and duck conservation objectives. To assess the compatibility of PBG with duck conservation, we estimated nest site selection and survival of duck nests on private lands managed with PBG in the unglaciated plains and prairie pothole region of North Dakota, USA. We located 478 duck nests of four species: 230 Blue-winged Teal (Spatula discors), 72 Gadwall (Mareca strepera), 71 Mallard (Anas platyrhynchos), and 105 Northern Pintail (A. acuta). Blue-winged Teal, Gadwall, and Mallard selected for ≥ 2 YSF and avoided ≤ 1 YSF patches. Northern Pintail selected for 1 YSF and 2 YSF patches. Year(s) since fire affected survival differently for Blue-winged Teal and Gadwall, indicating the importance of variable structure resulting from disturbance regimes. Additionally, nest survival decreased as litter accumulation increased for Blue-winged Teal and Gadwall. Our findings indicate that PBG created nesting areas for ducks in later YSF patches. However, we found contrasting effects of survival in selected patches for certain species. High selection but low survival was limited to a single patch and does not necessarily limit duck nesting activity with adjacent patches having high selection and survival. Additional management strategies may be required to ensure> 1 YSF patch consists of vegetation characteristics that will attract duck nesting activity. Given our results, it appears that variable structure resulting from PBG is in line with conservation objectives, and given the need for multi-objective management, this may be a good choice for land managers interested in game and non-game conservation goals.The post Patch-burn grazing provides resources for upland-nesting ducks first appeared on Avian Conservation and Ecology.
  PubDate: Tue, 04 Apr 2023 16:44:45 +000
High breeding success of the European Starling compared to native species
in a recently invaded natural forest of South America
- Authors: Adele Mullie
  Abstract: Invasive species present numerous threats to ecosystems as they compete with other species for resources and displace them from their habitats. One of the most invasive birds is the European Starling (Sturnus vulgaris), which recently invaded and started to expand throughout South America. Despite its negative impacts on the South American native fauna, there is no information on its breeding success, the factors affecting it, and its population recruitment rate. We monitored 100 European Starling nests in a native forest of central-eastern Argentina during the 2020-2021 and 2021-2022 breeding seasons. We estimated breeding parameters for the population (clutch size, number of fledglings, nest survival, among others) and measured nest-site features at different spatial scales to assess if they influenced nest survival and productivity. Starlings started breeding earlier than native species, used three cavity types (natural, woodpecker, and Rufous Hornero, Furnarius rufus), produced ~3 fledglings per successful nest, and had a 38% estimated nest success probability. Daily survival rates were negatively related to nest-tree diameter at breast height (DBH) but not related to landscape features. Nest survival and productivity were higher than those of native cavity-nesting birds. Moreover, starling successful occupancy of cavities earlier in the season may delay native cavity-nesting birds nest initiation dates, which negatively affects their breeding success. The inverse relationship between DBH and nest survival could indicate preservation of mature trees may help to reduce nest success rate but such a relationship deserves further study. The high reproductive rates in our study and effective nest usurpation by starlings shown elsewhere suggests that the effect of starlings on endangered native species needs further study and starlings may need to be controlled.The post High breeding success of the European Starling compared to native species in a recently invaded natural forest of South America first appeared on Avian Conservation and Ecology.
  PubDate: Tue, 04 Apr 2023 12:44:23 +000
Experts’ opinions on threats to Leach’s Storm-Petrels (Hydrobates
leucorhous) across their global range
- Authors: Paul
  Abstract: Seabirds are declining globally, though the threats they face differ among and within species and populations. Following substantial population declines at several breeding colonies, Leach’s Storm-Petrel (Hydrobates leucorhous) was uplisted from Least Concern to Vulnerable by the International Union for Conservation of Nature (IUCN) in 2016. Reasons for these declines are unclear, and it is important to identify threats the species faces across its global breeding range to guide research directions and inform conservation efforts. We solicited feedback from 37 Leach’s Storm-Petrel scientific experts from eight countries on the importance of different threats facing the species on land and at sea. Perceived threats to extant colonies varied spatially, with a consensus within regions for main threats. Most researchers agreed that the main threats at or near colonies are avian and mammalian predators and onshore light attraction. At-sea threats have been less studied and were harder to identify and rank, but include offshore lights and structures, spatial shifts in prey, and contaminants. Climate change was not listed specifically because of its multifaceted repercussions, but several perceived threats are linked to climate change. Globally, introduction of mammalian predators is an overarching driver of seabird colony decline or extirpation; thus biosecurity must be considered an important measure for the conservation of storm-petrels. In addition, filling knowledge gaps and implementing a series of regionally relevant and targeted strategies that lead to small but cumulative conservation successes may be the best approach for this species.The post Experts’ opinions on threats to Leach’s Storm-Petrels (Hydrobates leucorhous) across their global range first appeared on Avian Conservation and Ecology.
  PubDate: Mon, 03 Apr 2023 13:34:17 +000
Natal origins of Mallards harvested in the Atlantic Flyway of North
America: implications for conservation and management
- Authors: Adele Mullie
  Abstract: Appropriate management and conservation of migratory species requires knowledge of connectivity between natal or breeding sites and stopover or wintering sites. For game species, such as waterfowl, knowledge of source areas that produce juveniles, which are available for harvest in the autumn-winter, is of considerable interest. External markers have long been used in mark-recapture studies to identify breeding grounds of waterfowl. However, this approach is biased toward regions of marking effort and is logistically difficult in remote locations. Harvest management of Mallards (Anas platyrhynchos) in the U.S. portion of the Atlantic Flyway has assumed that the majority of harvested birds in the U.S. were produced there. We tested this assumption by inferring regions of natal origins of juvenile Mallards (n = 1254) harvested during the 2018–2019 and 2019–2020 hunting seasons in all states in the Atlantic Flyway using stable-hydrogen isotope analyses of breeding-ground grown feathers (δ²Hf). We created a species-specific feather isoscape and applied a Bayesian assignment approach to identify probable regions of origin. We determined 64% of our sample had δ²Hf consistent with origins in Canada versus the U.S. Our data suggested all states harvested Mallards that had origins from the U.S. and Canada throughout their entire hunting season. Our results contrast with long-term breeding population estimates which suggest the majority of breeding pairs of eastern Mallards occur in the U.S. We recommend further investigation into reasons for disparities in national natal origins of harvested Mallards.The post Natal origins of Mallards harvested in the Atlantic Flyway of North America: implications for conservation and management first appeared on Avian Conservation and Ecology.
  PubDate: Mon, 27 Mar 2023 17:30:11 +000