Endurance Specialty Holdings Ltd reported a net loss of almost $90 million in the opening three months of the year as its combined ratio climbed to 139.3 percent on global catastrophe losses.The re/insurer made a net loss of $87.4 million and $2.25 per share for the first quarter of 2011 versus a net income of $55.8 million and 91 cents per share for the same period last year.But the company's net premiums written rose 13.6 percent to $798.9 million during the respective period.Endurance's combined ratio included 12.7 percentage points of favourable prior year loss reserve development and 48.4 percentage points of catastrophe losses related to the New Zealand and Japan earthquakes, and the Australian floods.Its net investment income fell by $4 million to $52.5 million, while the company made an operating loss, excluding after-tax realized investment gains and losses and foreign exchange gains and losses, of $96.6 million and $2.47 per share and an operating loss on average common equity for the quarter of 4.1 percent in the first quarter.Book value per share meanwhile was $51.52, down 2.3 percent from December 31, 2010.David Cash, CEO of Endurance, said: “Our first quarter results were impacted by the exceptional frequency and severity of global catastrophe losses that occurred. I am pleased with Endurance's performance through these events, as our losses were within our expectations and tolerances for these types of events, a testament to the quality of our underwriting and risk management.”The increase of $83.4 million in net premiums written in the Insurance segment in the first quarter of 2011 compared to the first quarter of 2010 was predominantly due to growth in the agriculture line of business driven by commodity prices that were significantly higher than a year ago. Within the other Insurance segment lines of business, modest growth in the casualty and professional lines of business was partially offset by modest declines in the property and healthcare lines of business.Partially offsetting this growth was a decline in net premiums written within the surety and other line of business from reduced participations on certain renewal contracts and from several large contracts that were not renewed due to competitive market conditions.The combined ratio in the reinsurance segment for the first quarter increased compared to the same period in 2010 due to a higher net loss ratio which included 84.1 points of catastrophe losses related to the earthquakes in New Zealand and Japan and the Queensland floods in Australia, versus 29.6 points of catastrophe losses in the first quarter of 2010 and higher levels of IBNR reserves for short tailed lines given the higher frequency of catastrophe events this year.At March 31, 2011, Endurance's shareholders' equity was $2.41 billion or $51.52 per share versus $2.85 billion or $52.74 per share at December 31, 2010.