## 1 Introduction  
Offspring mortality is directly linked to the success of a species, so investigating reasons for mortality is of importance in any species where mortalities are occurring [1]. High mortality and low calf weaning rates have had the greatest impact on productivity in northern Australian beef cattle production [2]. Similarly to many animal species, data collected during birthing events and the first few days of life could provide critical information to understand factors contributing to such losses [3; 4; 5; 6; 7]. Calf mortality is seemingly high with 71 calves weaned for every 100 cows exposed to a bull in northern Australia, compared to 86% in southern Australian enterprises [8]. Calf mortalities are likely caused by a combination of factors including miss-mothering, wild dog predation, diseases and mustering practices, although the relative contribution of each risk factor has not been identified [2]. The lack of information is a result of the difficulties collecting data on newborn calves due to the remoteness, vegetation density, hilly terrain and large scale of the paddocks. For example, stocking rates in northern Australia are often as low as 1 animal per 20 hectares and paddock sizes can often be in excess of 120 square kilometers [9]. Caluving alert devices and technologies to measure calving time and location have been used in deer, elk and bighorn sheep using vaginal implant transmitters (VIT) and GNSS collars with some success [4; 6; 10; 11; 12; 13; 14]. However, only 5% of VIT devices deployed in wild elk resulted in the successful capture of an elk calf at birth, with more calves being found after visual surveillance was conducted [13]. In addition, pre-birth shedding of the VIT occurred in half of all cases, which was possibly caused by the size and shape of the implant in relation to the female [6; 10; 15]. Nevertheless, VIT allowed the collection of information close to the time of calving for the identification of potential risk factors for mortality [14]. Importantly, no studies have been published using satellite birth alert systems in cattle under extensive conditions. In contrast to wildlife, calving site is often not relevant in farmed cattle because of small areas (paddocks or barns), the timing of device placement can be controlled, and approximate calving due dates are known [11; 12; 13; 14]. A study on a commercial beef enterprise in Japan used wireless vaginal temperature sensors to measure the drop in temperature with expulsion of the device inserted seven days prior to calving, reporting 625 true alerts out of 669 calving events [16]. A calving alert system for applications in extensive grazing was successfully trialed in regions with a cellular network consisting of a transceiver with GPS receiver embedded in the device sutured on the vulva of the cow, although the battery life was only one month [17]. However, beef cattle production in northern Australia resembles the conditions of wild or feral animals, which require more robust systems with geolocation of the birthing site. Furthermore, cellular coverage is very limited and animals roam in very large paddocks. Therefore, satellite communication for birth alerts may be one of the few options to make the data available in real-time to observe the newborn calves before they move away from the birthing site or are predated. Finally, calving alert devices would also require the ability to remain operational and implanted for long periods of time (e.g., up to six months) in extensive conditions with year-round calving and mustering only twice per year. Limitations such as large-scale operations and the remote nature of production in extensive cattle herds means that the contribution of risk factors to calf mortality are not understood, requiring a method to track animals around birth to gather information to identify reasons for high calf mortality.