作者
劉曦敏^* (國立臺北大學經濟學系)
陳孝琪 (國立臺北大學經濟學系)

Authors
Shi-Miin Liu^* (Department of Economics, National Taipei University)
Hsiao-Chi Chen (Department of Economics, National Taipei University)

中文摘要
本文嘗試探討處理流浪動物的最適經濟政策。我們建構了一個兩階段的賽局，用以刻劃主管機關、寵物店和消費者之間的互動。 尤其，一個簡單的 Hotelling 模型可用來將購買與領養寵物者的行為內生化。我們的結果顯示，當社會福利的極大化是目標且寵物市場為不完全競爭時，主管機關可以對寵物的購買者課稅或進行補貼。 另一方面，當寵物市場為完全競爭時，主管機關應該對購買寵物者課稅。相對地，當流浪動物數目的極小化是目標時，對寵物的購買者課稅是主管機關的最佳選擇。無論寵物的飼養成本和流浪動物造成的環境代價是線性的或二次式的函數型態，也無論寵物市場為完全或不完全競爭，這個結果都成立。

Abstract
This paper investigates optimal economic policies, that deal with stray animals. We construct a two-stage game to characterize the interactions among the regulator, pet shops, and consumers. In particular, we employ a simple Hotelling (1929) model to endogenize the behaviors of dog/cat purchasers and adopters and show that the regulator may tax or subsidize pet-animal buyers if it aims to maximize social welfare in an imperfectly competitive pet-animal market. On the other hand, taxing pet-animal buyers is the regulator's best choice in a perfectly competitive pet-animal market. These results hold under both linear and quadratic breeding-cost and strays' environmental-damage functions. By contrast, when the regulator is targeting to minimize the number of stray animals, taxing dog/cat buyers is the best choice. This outcome holds whether the pet-animal market is perfectly or imperfectly competitive and whether the breeding-cost and strays' environmental-damage functions are linear or quadratic.

中文關鍵字
流浪動物；外部性；稅；補貼；完全競爭；不完全競爭

Keywords
Stray Animals; Externality; Tax; Subsidy; Perfect Competition; Imperfect Competition