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For many species, breeding population size is an important metric for assessing population status. A variety of simple methods are often used to estimate this metric for ground‐nesting birds that nest in open habitats (e.g., beaches, riverine sandbars). The error and bias associated with estimates derived using these methods vary in relation to differing monitoring intensities and detection rates. However, these errors and biases are often difficult to obtain, poorly understood, and largely unreported. A method was developed to estimate the number of breeding pairs using counts of nests and broods from monitoring data where multiple surveys were made throughout a single breeding season (breeding pair estimator; BPE). The BPE method was compared to two commonly used estimation methods using simulated data from an individual‐based model that allowed for the comparison of biases and accuracy. The BPE method underestimated the number of breeding pairs, but generally performed better than the other two commonly used methods when detection rates were low and monitoring frequency was high. As detection rates and time between surveys increased, the maximum nest and brood count method performs similar to the BPE. The BPE was compared to four commonly used methods to estimate breeding pairs for empirically derived data sets on the Platte River. Based on our simulated data, we expect our BPE to be closest to the true number of breeding pairs as compared to other methods. The methods tested resulted in substantially different estimates of the numbers of breeding pairs; however, coefficients from trend analyses were not statistically different. When data from multiple nest and brood surveys are available, the BPE appears to result in reasonably precise estimates of numbers of breeding pairs. Regardless of the estimation method, investigators are encouraged to acknowledge whether the method employed is likely to over‐ or underestimate breeding pairs. This study provides a means to recognize the potential biases in breeding pair estimates. For many avian species, breeding population size is an important metric for assessing population status. We developed a method to estimate the breeding population using counts of nests and broods from monitoring data where multiple surveys were made throughout a single breeding season. We used simulated and empirical data to evaluate our method.

The Hawar Islands, located near Bahrain, were designated a Ramsar Site in 1997, and a survey of Sooty Falcons began in 1998, documenting 15 breeding pairs. By 2006, numbers had declined to 10 pairs, with chick ringing efforts conducted to monitor the population. After a 15-year gap, surveys resumed in 2021 and 2023, identifying only 6 occupied nests in 2021 and a possible 5–7 pairs in 2023. The breeding season occurs in August, coinciding with extreme heat and the arrival of migratory birds, which serve as prey. Despite abundant nesting sites, Sooty Falcon numbers have declined, possibly due to changes in prey availability rather than human disturbance. Observations suggest a connection between Hawar and Oman populations, evidenced by a recovered ringed bird from Oman. Urgent conservation efforts, including better funding, advanced technology, and further ecological studies, are necessary to ensure the species’ survival on Hawar.

For long‐lived species with biparental care, coordination and compatibility in the foraging behavior of breeding mates may be crucial to successfully raise offspring. While high foraging success is clearly important to reproductive success, it might be equally important that the mate has a complementary foraging strategy. We test whether breeding partners have similar or dissimilar foraging strategies in a species where both partners share breeding responsibilities and exhibit high mate fidelity (thick‐billed murre; Uria lomvia). To examine whether thick‐billed murres showed complementary in foraging strategies, we attached GPS accelerometers to both partners within 40 thick‐billed murre chick‐rearing pairs. Individuals within a breeding pair were dissimilar in their foraging trip distance and in their number of dives during foraging trips compared to randomized pairs. Breeding partners were also more similar in wing length than randomized pairs. This result could be related to individual quality as individuals select similar sized partners or select sites that lead to similar sized partners. We conclude that foraging strategy diversity could be maintained in this population either because individuals prefer partners with foraging strategies complementary to their own, or because partners diverge in foraging strategies over multiple breeding season together. In long‐lived species with biparental care, such as the thick‐billed murre, coordination of foraging strategies between mates may be crucial for raising offspring. This study found that breeding partners had dissimilar foraging behaviors, such as trip distance and dive numbers, compared to randomized pairs, yet they were more similar in wing length. This suggests that foraging strategy diversity may be maintained due to complementary foraging strategies or divergence over time between partners.

Gull chicks beg for food from their parents. Peacocks spread their tails to attract potential mates. Meerkats alert family members of the approach of predators. But are these--and other animals--sometimes dishonest? That's what William Searcy and Stephen Nowicki ask in The Evolution of Animal Communication. They take on the fascinating yet perplexing question of the dependability of animal signaling systems. The book probes such phenomena as the begging of nesting birds, alarm calls in squirrels and primates, carotenoid coloration in fish and birds, the calls of frogs and toads, and weapon displays in crustaceans. Do these signals convey accurate information about the signaler, its future behavior, or its environment? Or do they mislead receivers in a way that benefits the signaler? For example, is the begging chick really hungry as its cries indicate or is it lobbying to get more food than its brothers and sisters? Searcy and Nowicki take on these and other questions by developing clear definitions of key issues, by reviewing the most relevant empirical data and game theory models available, and by asking how well theory matches data. They find that animal communication is largely reliable--but that this basic reliability also allows the clever deceiver to flourish. Well researched and clearly written, their book provides new insight into animal communication, behavior, and evolution.

In Europe, population estimates of breeding birds are produced nationally and are periodically compiled at EU or pan-European scales. Until now, no other source was available to explore the robustness of these estimates. In this study, we compared population sizes reported in the latest edition of the European Red List of Birds (ERLoB) with those produced using data from the second European Breeding Bird Atlas (EBBA2) to assess their consistency and determine parameters behind variability in population estimates that deserve further attention in the future. In general, European population estimates derived from summing local abundance data from EBBA2 were similar to those obtained from ERLoB, although for some species they differed considerably, particularly in those distributed mainly in southern Europe. National population estimates from EBBA2 also did not differ markedly from those in ERLoB. However, we found that EBBA2 provided larger national population sizes than ERLoB for widespread species, suggesting that spatial information is more relevant for properly assessing their population size than for localised species. Our analysis also showed that, in general, population estimates based on robust methodological protocols (e.g. complete counts, statistical inference) contributed to reducing differences between ERLoB and EBBA2 values. Interestingly, EBBA2 and ERLoB estimates were quite similar for species classified in Europe as “Threatened” or “Near Threatened”, whereas the values for “Least Concern” species were consistently different between these two sources. Our results indicate which type of species would benefit from additional efforts to improve national population estimates and their consistency across countries, issues that are of paramount importance for guiding conservation strategies in Europe.

In bi-parental species, breeding pairs cooperate to regulate incubation duration through nest-relief behavior, using vocal signals to communicate when exchanging incubation duties. To better understand this behavior, two important questions are (1) which vocalizations are mainly used with nest-relief behavior and (2) which parent initiates nest relief using these vocal signals. In this study, we examined the vocalizations and behaviors of incubating pairs of Kentish plovers ( Charadrius alexandrinus ). We categorized nest-relief calls and investigated the major call types used when initiating nest relief and when the partner responded and analyzed the number of initiating calls by sex and behavioral role (relieving or incubating). We observed that they used four call types: type A (“tit”), type B (“pee”), type B-long (“PEEjurrr”), and type C (“rrooh”). Call type C, which is known as an agonistic call, was the most used nest-relief call. Additionally, we found that relieving individuals produced initiating calls more frequently than incubating individuals, but there were no sex differences. These results suggest that Kentish plovers make use of specific call types during nest relief, and we discuss the possibility of relationships between nest-relief calls and coordinative behavior when dividing labor in a parental pair.

Constructed islands with adequate nesting cover provide secure nesting sites for ducks because islands restrict access by mammalian predators. These islands are costly to construct and should be placed in areas that ensure the greatest use by nesting ducks. We studied mallard (Anas platyrhynchos) and gadwall (A. strepera) nesting on constructed islands in North Dakota in 1996 (n = 20) and 1997 (n = 22) to evaluate factors—particularly amount of perennial grass cover in the surrounding landscape and density of breeding pairs—that possibly influence numbers of initiated nests. We also examined effects of island characteristics, such as island vegetation, on numbers of nests. Numbers of mallard and gadwall nests on islands were negatively related to amounts of perennial grass cover in the surrounding uplands. Numbers of mallard nests were positively related to percentages of tall dense cover on islands. We found no effects of breeding-pair density on numbers of nests initiated by either species, possibly because breeding pairs were abundant on all study sites. Percent shrub cover on islands was a better predictor of island use than was percent tall dense cover. Island use by these species increased with island age and distance from mainland shore. Amounts of perennial cover in landscapes should be primary considerations in determining where to build islands. Our data suggest that use of islands by nesting mallards and gadwalls is greatest in landscapes with little perennial grass cover (i.e., high amounts of cropland). Other researchers documented a positive relation between nest success in upland covers and amount of perennial grass cover in the landscape. Therefore, islands constructed in landscapes with little perennial cover should provide greater gains in duck recruitment rates than islands constructed in landscapes with greater amounts of perennial grass cover.

Florida is a stronghold for the continental U.S. breeding population of Wilson's Plover (Anarhynchus wilsonia), but data gaps exist in areas logistically challenging to survey. We estimated the species distribution and abundance in the Florida Keys by surveying 45 potential nesting areas. We used the independent double-observer method in a subset of the surveyed nesting areas (n = 20) to estimate the species' detection probability and unbiased abundance during the onset of the nesting season (23–26 Apr 2019). We developed 4 models to assess the effects of observer-group and nesting habitat availability on detectability and abundance. The most supported model included a positive effect of habitat availability on the number of breeding pairs and constant detection probability. Using the detection probability from our best models, we estimated 82 breeding Wilson's Plover pairs (95% CI: 74–142) in the surveyed areas. We documented that 18% of the statewide Wilson's Plover breeding population is in the Florida Keys. This critical component of the breeding population is vulnerable to local declines because of limited available habitat and the predicted habitat loss due to climate change. Our methodology is relevant to researchers across the Wilson's Plover breeding range interested in estimating the species' abundance and applies to other shorebird species globally. La Florida es un conocido baluarte para la población reproductiva de Anarhynchus wilsonia en la región continental de los Estados Unidos, pero existen vacíos de información en áreas logísticamente difíciles de muestrear. Estimamos la distribución y la abundancia de la especie en los Cayos de Florida a través de muestreos en 45 áreas reproductivas potenciales. Usamos el método de doble observador independiente en una submuestra de las áreas seleccionadas (n = 20) para estimar la probabilidad de detección y abundancia de la especie al inicio de la temporada de anidación (23–26 de abril de 2019). Utilizamos 4 modelos para evaluar los efectos del grupo de observadores y la disponibilidad del hábitat de anidación sobre la detectabilidad y la abundancia de A. wilsonia, respectivamente. El mejor modelo incluyó un efecto positivo de la disponibilidad de hábitat en el número de parejas y una probabilidad de detección constante. Utilizamos la probabilidad de detección de nuestros mejores modelos para estimar 82 parejas reproductivas (95% IC: 74–142) en las áreas muestreadas. Los Cayos de Florida albergaron 18% de la población reproductora de A. wilsonia en Florida, implicando una posible vulnerabilidad a la disminución de la población dada su distribución actual en el área y el paisaje altamente dinámico de la región. Nuestra metodología es relevante para estimar la abundancia de la especie a lo largo de su rango de distribución de cría y puede ser implementado para otras aves playeras. Palabras clave: doble-observador independiente, estimación poblacional, monitoreo de aves playeras, parejas reproductoras, probabilidad de detección.

The plasticity in the trophic ecology, the breeding phenology, and the low nesting site fidelity would be the reasons why most of the gentoo penguin (Pygoscelis papua) populations breeding in the western Antarctic Peninsula and islands of Scotia Arc remained stable or increasing, despite the changing environmental conditions. Regardless of the overall trend, recent studies revealed a decline in the abundance of some gentoo penguin populations at those regions. Therefore, it is highly valuable to update the population size of each colony in order to confirm the current trends of individual colonies and generate a comprehensive overview of the population status. We report the abundance and breeding performance of gentoo penguins at the Stranger Point/Cabo Funes colony from 2000/2001 to 2018/2019. During the last season, 5383 breeding pairs and 5545 chicks in crèche were counted. Despite there were considerable inter-annual fluctuations over the study period, the total number of gentoo penguin breeding pairs increased by 74.6% (+ 3.1% per annum), while the number of chicks crèched increased by 60.0% (+ 2.6% per annum). However, the index of breeding success remained relatively constant over time, varying between 0.74 and 1.23 chicks in crèche/breeding pairs. Gentoo penguins have life-history strategies that are advantageous to face the environmental variability, allowing the species to maintain their breeding performance stable over time and enhance their resilience, which can favour the population growth at Stranger Point.

In the late eighties, Greylag Geese ( Anser anser ) started to colonise an urban area previously void of geese in southwestern Germany. Between 2004 and 2020, in a period of steady population increase with subsequent population stagnation, we analysed two measures of reproductive success: (1) the relation between freshly hatched to fledged young for each brood and (2) the probability of a hatchling to survive to fledging. We were able to show that the dispersal of pairs from the nesting site to a different brood rearing area resulted in higher reproductive success. However, the increasing population size of Greylag Geese and the number of breeding pairs of recently immigrated Egyptian Geese ( Alopochen aegyptiaca ) had a negative impact on reproductive success, indicating density dependence. Our results show that newly established populations in urban settings do not grow indefinitely, which is an important fact that should be taken into account by wildlife managers.