Cecilia Soldatini

An ecological approach to birdstrike risk analysis

Airports are peculiar developed habitats that, besides being extremely noisy and unappealing to some bird species, are highly attractive to others. Bird–aircraft collisions, or birdstrikes, cause losses in terms of human lives, direct monetary losses and associated costs for the civil aviation industry. In recent years, birdstrike risk assessment studies have focused on the economical aspects of the damage caused by wild animals and the hazards of wildlife–aircraft collisions, while an ecological approach, taking into account animal behaviour for the analysis of such events, has seldom been adopted. We conducted a risk analysis for birdstrikes at the Venice Marco Polo International Airport (VCE), Italy. We defined the key variables involved in these events and summarised their interactions in a single metric risk index we called the “Birdstrike Risk Index” (BRI). Our aim was to provide a tool for birdstrike risk analysis that described the risk on the basis of the actual presence of birds at airports. The application of the BRI at VCE allows relative risks across species to be defined, providing information for prioritising management actions. Furthermore, due to the seasonality of bird species presences, the application of the BRI to a long-term data series should give clues of birdstrike risk in future scenarios. This new ecological approach that we applied to a particular airport could easily be adapted for use at other airports worldwide and integrated into risk assessment procedures. The study results and the BRI tool are addressed to scientific consultants of airport safety managers.

On the use of pharmacological sterilisation to control feral pigeon populations.

The use of chemosterilisation for controlling feral pigeon populations was investigated by: (1) quantifying the reproductive activity of pigeons in two Italian cities; (2) testing the efficacy of nicarbazin, an anticoccidial drug with rapid and reversible effects on the reproduction of laying hens, on groups of paired pigeons maintained in open aviaries; and (3) simulating the effects of the use of nicarbazin on a hypothetical population, allowing for the reproductive productivity recorded in (1) and the efficacy of this drug as obtained in (2). Breeding attempts were recorded all year round in both study sites with a minimum peak in September-October, a maximum in March-July, but with active nests in winter too. In terms of the sterility activity of the drug, the results showed only a partial inhibition of reproduction of pigeons fed ∼38-82 mg nicarbazin day −1 (kg bodyweight) −1 (500 and 800 ppm in feed), which, according to the simulations, would produce only a fleeting reduction of their abundance in the field. Data do not seem to support the use of this drug as an effective control method for feral pigeons, and they cast doubts on the opportunity to make use of chemosterilants, which produce only partial and reversible effects. The use of this drug could perhaps be considered only as part of an integrated pest-management program, which necessarily has to include the reduction of carrying capacity of the urban environment.

Roof nesting by gulls for better or worse

Since the early 1970s in Italy, the yellow‐legged gull Larus michahellis has been colonizing new kinds of nesting areas, in particular moorland and the rooftops of inhabited buildings. The incidence of rooftop colonies is now such that the yellow‐legged gull has come in many urban areas to be regarded as a pest. Yet its colony structure and breeding biology in the urban situation in Italy have remained largely undocumented. This paper reports observations of yellow‐legged gulls breeding in the town of Venice and in the surrounding lagoon during the 2003–2005 breeding seasons. The aim of this study was to examine the performance of birds breeding in natural and urban areas and to investigate the links between the natural and the newly established urban colony. For this, we analysed and compared factors indicative of breeder quality. Breeding performance was not substantially different in the two colonies. This suggests that gulls are successfully exploiting a new habitat, adapting to new resources, as other opportunistic species do.

Linking food web functioning and habitat diversity for an ecosystem based management : a Mediterranean lagoon case-study

We propose a modelling approach relating the functioning of a transitional ecosystem with the spatial extension of its habitats. A test case is presented for the lagoon of Venice, discussing the results in the context of the application of current EU directives. The effects on food web functioning due to changes related to manageable and unmanageable drivers were investigated. The modelling procedure involved the use of steady-state food web models and network analysis, respectively applied to estimate the fluxes of energy associated with trophic interactions, and to compute indices of food web functioning. On the long term (hundred years) temporal scale, the model indicated that the expected loss of salt marshes will produce further changes at the system level, with a lagoon showing a decrease in the energy processing efficiency. On the short term scale, simulation results indicated that fishery management accompanied by seagrass restoration measures would produce a slight transition towards a more healthy system, with higher energy cycling, and maintaining a good balance between processing efficiency and resilience. Scenarios presented suggest that the effectiveness of short term management strategies can be better evaluated when contextualized in the long term trends of evolution of a system. We also remark the need for further studying the relationship between habitat diversity and indicators of food web functioning.

A temporal analysis of the foraging flights of feral pigeons (Columba livia f. domestica) from three Italian cities

Foraging flights of feral pigeon populations may differ in occurrence and extent from town to town. In this paper, the annual pattern of such flights from three medium‐sized Italian cities (Venice, Parma and Lucca) is described and compared with that recorded for a Mediterranean population of wild rock doves from Sardinia. The data provide evidence of the similarity of these flights both within urban populations and between feral pigeons and wild rock doves. On the other hand, the presented results point to a noticeable flexibility of this behaviour, whose features seem finely adapted to the environmental features of an urban habitat and its surroundings. In particular, the distribution of food resources and of the annual trend of reproductive attempts appear to exert a leading role in shaping the characteristics of these flights.

Climate driven life histories: the case of the Mediterranean storm petrel.

Seabirds are affected by changes in the marine ecosystem. The influence of climatic factors on marine food webs can be reflected in long-term seabird population changes. We modelled the survival and recruitment of the Mediterranean storm petrel (Hydrobates pelagicus melitensis) using a 21-year mark-recapture dataset involving almost 5000 birds. We demonstrated a strong influence of prebreeding climatic conditions on recruitment age and of rainfall and breeding period conditions on juvenile survival. The results suggest that the juvenile survival rate of the Mediterranean subspecies may not be negatively affected by the predicted features of climate change, i.e., warmer summers and lower rainfall. Based on considerations of winter conditions in different parts of the Mediterranean, we were able to draw inferences about the wintering areas of the species for the first time.

Effects of human disturbance on cave-nesting seabirds: the case of the storm petrel

We tested the effects of human disturbance in two sub-colonies of Mediterranean storm petrel. We conducted three experiments to measure the capacity of the storm petrels to respond to stress. The part of the colony exposed to human disturbance resulted to be habituated and did not show chronic stress related to anthropogenic disturbance.

Wildlife strike risk assessment in several Italian airports: lessons from BRI and a new methodology implementation

The presence of wildlife in airport areas poses substantial hazards to aviation. Wildlife aircraft collisions (hereafter wildlife strikes) cause losses in terms of human lives and direct monetary losses for the aviation industry. In recent years, wildlife strikes have increased in parallel with air traffic increase and species habituation to anthropic areas. In this paper, we used an ecological approach to wildlife strike risk assessment to eight Italian international airports. The main achievement is a site-specific analysis that avoids flattening wildlife strike events on a large scale while maintaining comparable airport risk assessments. This second version of the Birdstrike Risk Index (BRI2) is a sensitive tool that provides different time scale results allowing appropriate management planning. The methodology applied has been developed in accordance with the Italian Civil Aviation Authority, which recognizes it as a national standard implemented in the advisory circular ENAC APT-01B.

Are Burrow Nesting Seabird Chicks Affected by Human Disturbance

Abstract. Many studies on the effects of human disturbance on birds have focused on adults and report mainly negative effects. Few focus on effects on chicks. Here, an experimental approach was used to determine effects of human disturbance on chick growth. Cassins Auklet chicks were assigned to one of three groups (control, low and high disturbance). In experimental groups, a person walked close to the burrow entrance four times or eight times a day, according to the disturbance level assigned. Growth (mass increment and wing length increase) was measured and compared between the three groups. Since adults are absent from the nest during the day, chicks, but not their parents, experienced the disturbance regime. Body condition and experience (age) of the parents did not influence peak or fledging mass of chicks subject to disturbance. Chicks were not affected by disturbance in the early stages of growth, while chicks in the experimental groups stopped gaining weight sooner than controls and fledged at lower weights (6 to 9% less) compared to chicks in the control group. Chicks in the high disturbance group had a lower peak (F2,68 = 7.53, P < 0.001) and fledging mass (F2,68 = 17.274, P < 0.001) compared to chicks in the control group, while chicks in the low disturbance group had a lower fledging mass (F2,68 = 17.274, P < 0.001) but similar peak mass. As subsequent survival of chicks is likely to be affected by their mass at fledging, the results show that it is necessary to consider the chick growth stage when making management plans for areas with burrow-nesting seabirds.

Old and novel methods for estimating Feral Pigeons (Columba livia f. domestica) population size: a reply to Amoruso et al. (2013)

In a recent paper Amoruso et al. (2013) proposed a novel method for estimating population size of Feral Pigeons, the Superimposed Urban Strata (SUS) method. In our reply we firstly comment on the lack of a complete review of the available literature. Secondly we point out that the SUS method does not account for birds detection probability and thus it is just a simple index of abundance as many others proposed in recent years. Thirdly, we question the approach used by the authors to evaluate the reliability of their method. To conclude, we believe that the SUS method is not truly innovative and that further investigations are needed before considering it as a reliable way for estimating Feral Pigeons populations size.