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We applied two recent approaches largely used in biological conservation: Threat Analysis (TAN) and Threat Reduction Assessments (TRAs), assessing the effectiveness of a project focused on two water-related bird species (common tern, Sterna hirundo and little tern, Sternula albifrons), commonly breeding in some wetlands of Italy. We used the IUCN standardized lexicon for the classification of threats, utilizing a panel of experts to assess a set of regime attributes (extent, severity and magnitude) of each human-induced disturbance. Our aims were: (i) through the TAN approach, to carry out an arrangement and quantification of the main threats acting on our focal species and select the priority ones; (ii) through the TRA approach, to test the effectiveness of an operational project focused on mitigating the threats and improving the breeding success of species (i.e., building rafts and floating islands to encourage their nesting). Using the TAN approach, experts identified the following human-induced threats (IUCN code): 6.1—Generic disturbance; 7.2—Water stress; 7.3—Salinization; 8.8—Vagrant dogs; 8.8—Mediterranean gulls; 8.8—Wild boars, all significantly different in their magnitude. Among them, wild boars and Mediterranean gulls appeared the priority threats with the greatest extent, intensity and magnitude. Using the TRA approach, after the project, we assessed an overall decrease in the threat magnitude of 23.08% (21.42% when considering only the threats directly affected by our project). These data suggest that further efforts should be devoted to achieving greater effectiveness of conservation actions focused on our target species. With limited time and resources to quantify threats, expert-based approaches could be useful for rapidly assessing the effectiveness of small conservation projects by providing a range of scores obtained following an analytical procedure. In this regard, Threat Analysis and Threat Reduction Assessment could be considered useful tools to support adaptive management in project management cycles.

In this study, Little Tern (Sternula albifrons) populations in Taiwan are examined based on two different types of data: mitochondrial control region DNA sequences and double digest restriction-site associated DNA (ddRAD) sequencing data. Feather samples were collected from 59 chicks across four known breeding colonies located on the eastern (Yilan and Hualien) and western (Penghu and Changhua) coasts of Taiwan. The results obtained are consistent in analyses and do not cluster into two geographical groups with respect to the eastern and western Taiwan. Furthermore, AMOVA analyses and pairwise ΦST/FST estimations based on both types of data reveal little to no differentiation among populations and between groups. The findings of this study suggest high population connectivity among Taiwan’s breeding colonies. Additionally, control region sequences of Taiwan’s Little Terns are compiled with those from Japan deposited in GenBank to compare genetic diversity and examine for phylogeographic breaks that could shape the diversity pattern of the species in eastern Asia. The resulting haplotype network does not clearly separate Taiwanese and Japanese populations, but the three most common haplotypes are prevalent for mainland Japan, Okinawa, and Taiwan. Little Tern populations may be frequently connected, but with some restrictions on gene flow causing moderate to great differentiation among the three. This is further supported by AMOVA analyses, pairwise ΦST estimations, and pattern of positive yet significant isolation by distance.

Domestic cats have a cosmopolitan distribution, commonly residing in urban, suburban and peri-urban environments that are also critical for biodiversity conservation. This study describes the impact of a desexed, free-roaming cat on the behavior of a threatened coastal seabird, the Australian Fairy Tern, Sternula nereis nereis, in Mandurah, south-western Australia. Wildlife cameras and direct observations of cat incursions into the tern colony at night, decapitated carcasses of adult terns, dead, injured or missing tern chicks, and cat tracks and scats around the colony provided strong evidence of cat predation, which led to an initial change in nesting behavior and, ultimately, colony abandonment and the reproductive failure of 111 nests. The death of six breeding terns from the population was a considerable loss for this threatened species and had the potential to limit population growth. This study highlights the significant negative impacts of free-roaming cats on wildlife and the need for monitoring and controlling cats at sites managed for species conservation. It also provides strong evidence against the practice of trap-neuter-release programs and demonstrates that desexed cats can continue to negatively impact wildlife post-release directly through predation, but also indirectly through fundamental changes in prey behavior and a reduction in parental care.

Between 2002 and 2019, monitoring of Common Tern and Little Tern along the Sava River near Zagreb, Croatia was conducted. Natura 2000 site “Sava kod Hrušćice” was designated to protect colony at river islands, with estimated population sizes of 100–150 pairs of Common and 20 pairs of the Little Tern. Flooding of the colony caused breeding failure in several years. Common Terns moved to breed on islands in gravel pits with a total population around 150 pairs, while Little Tern did not breed after 2010. In the last few years, terns have not bred at Hrušćica and the only colony inside the Natura 2000 site is situated on a breeding platform at Siromaja gravel pit. Channelling of rivers and hydropower plants are the main threats, changing natural dynamics of water level and causing reduction of gravel sediment in rivers.

The COVID-19 lockdown opened an opportunity to assess the response of animal populations to diminished human activities. As coastal dunes face many disturbances caused by increasing human activities, we assessed the effect of reduced human mobility on coastal bird diversity and abundance and on the Least Tern nest failure rate on an island in the southern Gulf of Mexico before, during, and after the lockdown to test the hypothesis that diminished tourism and recreational activities can contribute to the conservation of coastal ecosystems by increasing species richness and abundance and decreasing the nest failure rate. We used data from 2016 to 2021 to estimate nesting failure probabilities using Bernard’s cumulative distribution function, Kaplan‒Meier tests, and Cox regression for hazard rates. Bird species richness and abundance were compared using Kruskal‒Wallis rank tests. Factors related to breeding site preference were assessed using the BIOENV method. The lockdown did not affect species richness, but bird abundance was inversely related to pedestrian traffic (rho =  − 0.908, p < 0.0001, n = 48). Nest failure decreased during the lockdown in 2020 (p < 0.0001) due to reduced presence of people, which allowed occupancy of sites never used before. During the lockdown, the proportion of nest failure was lower than that in the other sampling years (p < 0.0001, φ range =  − 0.445 to − 0.278). Accordingly, diminished pedestrian traffic can increase nest survival (log-rank p < 0.0001). Policies to reduce beach pedestrian traffic will help strengthen wildlife conservation and building coastal resilience.

Many bird species of conservation concern have behavioral or morphological traits that make it difficult for researchers to determine if the birds have been uniquely marked. Those traits can also increase the difficulty for researchers to decipher those markers. As a result, it is a priority for field biologists to develop time- and cost-efficient methods to resight uniquely marked individuals, especially when efforts are spread across multiple States and study areas. The Interior Least Tern (Sternula antillarum athalassos) is one such difficult-to-resight species; its tendency to mob perceived threats, such as observing researchers, makes resighting marked individuals difficult without physical recapture. During 2015, uniquely marked adult Interior Least Terns were resighted and identified by small, inexpensive, high-definition portable video cameras deployed for 29-min periods adjacent to nests. Interior Least Tern individuals were uniquely identified 84% (n = 277) of the time. This method also provided the ability to link individually marked adults to a specific nest, which can aid in generational studies and understanding heritability for difficult-to-resight species. Mark-recapture studies on such species may be prone to sparse encounter data that can result in imprecise or biased demographic estimates and ultimately flawed inferences. High-definition video cameras may prove to be a robust method for generating reliable demographic estimates.

Nest usurpation is a strategy in which an individual or pair of one species takes over the nest of another species. This is the first documented occurrence of a Piping Plover (Charadrius melodus) pair usurping an Interior Least Tern (Sternula antillarum athalassos) nest. The Piping Plovers incubated the three Interior Least Tern eggs in the nest, and all three eggs hatched. The adult Piping Plovers accompanied and brooded the Interior Least Tern chicks for 1 day post-hatching, but we did not see the adult Piping Plovers nor the Interior Least Tern chicks after that day. The Piping Plovers likely usurped the Interior Least Tern nest because they developed hormonemediated broodiness after they lost the eggs from their two previous nesting attempts. When the Piping Plovers encountered an unattended Interior Least Tern nest with eggs, they instinctively took the nest and its contents as their own.

Monitoring is needed to assess conservation success and improve management, but naïve or simplistic interpretation of monitoring data can lead to poor decisions. We illustrate how to counter this risk by combining decision‐support tools and quantitative counterfactual analysis. We analyzed 20 years of egg rescue for tara iti (Sternula nereis davisae) in Aotearoa New Zealand. Survival is lower for rescued eggs; however, only eggs perceived as imminently threatened by predators or weather are rescued, so concluding that rescue is ineffective would be biased. Equally, simply assuming all rescued eggs would have died if left in situ is likely to be simplistic. Instead, we used the monitoring data itself to estimate statistical support for a wide space of uncertain counterfactuals about decisions and fate of rescued eggs. Results suggest under past management, rescuing and leaving eggs would have led to approximately the same overall fledging rate, because of likely imperfect threat assessment and low survival of rescued eggs to fledging. Managers are currently working to improve both parameters. Our approach avoids both naïve interpretation of observed outcomes and simplistic assumptions that management is always justified, using the same data to obtain unbiased quantitative estimates of counterfactual support.

We observed a Killdeer (Charadrius vociferus) incubating a nest containing 1 Piping Plover (Charadrius melodus) egg and 2 Killdeer eggs at a sand and gravel mine in West Point, Nebraska. Four days later, the nest contained 1 Piping Plover egg and 4 Killdeer eggs. Two days later, the Piping Plover egg was absent, and the 4 Killdeer eggs remained in the nest. Eight days later the nest was destroyed. We speculate the nest began as a Piping Plover nest and was usurped by a Killdeer pair. To our knowledge, this is the first documentation of a nest containing eggs from both species. Observamos a un chorlito Charadrius vociferus incubando un nido que contenía 1 huevo de chorlito Charadrius melodus y 2 huevos de chorlito C. vociferus en una mina de arena y grava en West Point, Nebraska. Cuatro días despúes, el nido contenía 1 huevo de chorlito C. melodus y 4 de chorlito C. vociferus. Dos días después, el huevo de chorlito C. melodus estaba ausente y los 5 huevos de chorlito C. vociferus permanecían en el nido. Ocho días después el nido fue destruido. Especulamos que el nido inició como nido de chorlito C. melodus y fue usurpado por una pareja de chorlito C. vociferus. Por lo que sabemos, este es el primer caso documentado de un nido que contenía huevos de ambas especies. Palabras clave: Charrán menor, minas de arena y grava, monitoreo de nidos de aves costeras, Platte River, Sternula antillarum, usurpación de nido.

Many ground-nesting bird species are suffering from habitat loss and population decline. Data on population ecology and demography in colonies of threatened species are thus essential for designing effective conservation protocols. Here, we used extensive ringing and observation data to estimate directly, for the first time, the survival rate of juvenile and adult Little Tern (Sternula albifrons), as well as testing for a possible effect of age on probability of survival. We estimated adult annual survival rate to be 0.77, and juvenile (first year) survival to be 0.49 with a possible linear decrease in the survival rate of the juveniles that ranged from 0.681 to 0.327. We found no evidence that survival was age-dependent among the early age classes after the first year. We discuss these findings in light of survival estimates for other species, and their implications for the Little Tern conservation.